中国生态农业学报(中英文)

Developmental genetic and molecular ecological properties of rice (Oryza sativa L.) grain filling

LIN Wen-Xiong, LI Zhong, CHEN Jun, ZHANG Zhi-Xing, CHEN Ting

2011, 19(6): 1237-1242. doi: 10.3724/SP.J.1011.2011.01237

Abstract(1161) PDF(1658)

Abstract:
From the perspectives of developmental genetics and molecular ecology, this study reviewed the current state and issues of local and international rice grain-filling research. The authors contended that rice grain development was a complicated molecular ecological process, involving signal transductions, multi-gene regulations and environmental interactions. Different gene expressions in space and time, coupled with the action modes of functional proteins in superior and inferior grains caused significant differences in developmental programs of endosperm cells, grain-filling rates and dry matter accumulation at different spikelet positions on the panicle. Previous studies showed that superior grains were usually filled earlier and faster, leading to a significant genetic stability. The reverse was true for inferior grains, where stagnant and poor properties were associated with seed development and grain filling. It was noted that genetic characters were easily regulated by environmental factors during inferior rice grain-filling. Molecular genetic manipulations and molecular ecological regulations were two effective ways of improving inferior grain endosperm cell development, timely initiation of inferior grain filling, high percent setting and 1000-grain weight, and high yield. It was therefore emphasized to deeply understand the underlying mechanisms and properties of genetic ecology in grain filling (and especially in inferior grain-filling processes). This had become a priority grain production research area across the globe. Based on current understandings, it was suggested to focus further studies on investigating and answering the critical scientific questions of why there existed a stagnant phase in inferior grain filling and how different were protein expressions and associated functions of relevant genes between superior and inferior grains during the period of grain-filling.

Effect of Zn and P supply on grain Zn bioavailability in wheat

MAI Wen-Xuan, TIAN Xiao-Hong, LU Xin-Chun, YANG Xi-Wen

2011, 19(6): 1243-1249. doi: 10.3724/SP.J.1011.2011.01243

Abstract(1270) PDF(1083)

Abstract:
Phytic acid is not only the richest form of P, but also a main element reducing zinc bioavailability in wheat grains. A field experiment was conducted in a split-split design with 4 wheat genotypes (“Zhongyu 6”, “Xiaoyan 22”, “Xiza1” and “Zhengmai 9023”) of varied zinc efficiency. The experiment investigated the interactions of P, Zn and phytic acid in wheat, and the effects of P and Zn fertilization on Zn bioavailability in wheat grains. Two rates of zinc [0 kg(Zn)·hm^-2 and 7 kg(Zn)·hm^-2] and five rates of P [0 kg(P₂O₅)·hm^-2 (deficient), 50 kg(P₂O₅)·hm^-2 (low), 100 kg(P₂O₅)·hm^-2 (suitable), 150 kg(P₂O₅)·hm^-2 (high) and 200 kg(P₂O₅)·hm^-2 (excess)] were designed. The results showed that Zn application obviously increased soil available Zn content. Even after wheat cultivation, soil available Zn content under Zn treatment was higher than that under no Zn treatment. Meanwhile, P concentration, P/Zn ratio, phytic acid concentration and phytic acid/Zn²⁺ molecular ratio in wheat grains slightly dropped by 0.5%, 1.85%, 2.7% and 6.2%, respectively. Zinc bioavailability increased slightly because of Zn application. Also phytic acid concentration and phytic acid/Zn²⁺ molecular ratio dramatically increased with P treatment. For instance, increasing P treatment from 0 to 100 kg·hm^-2 increased phytic acid concentration and phytic acid/Zn²⁺ molecular ratio by 13.4% and 25.94% respectively, while decreasing zinc bioavailability in wheat grain. Similarly, wheat grain phytic acid concentration and phytic acid/Zn²⁺ molecular ratio increased at low P treatment and decreased at high P treatment, and peaked at 100 kg·hm^-2 and 150 kg·hm^-2 P treatment with values of 5.02 mg·g^-1 and 11.56 respectively. Excessive P treatment decreased phytic acid concentration in wheat grain. Furthermore, wheat grain phytic acid/Zn²⁺ molecular ratio under suitable (100 kg·hm^-2) P treatment was similar to that under low (50 kg·hm^-2) P treatment, but lower than that under high (150 kg·hm^-2) P treatment. Hence suitable P treatment was considered a better measure for zinc nutrition in wheat grain. It was concluded that zinc bioavailability in wheat grain could increase under suitable combinations of Zn and P treatment. P treatment was noted to be more important than Zn treatment.

Effects of nitrogen on metabolism and dry matter accumulation of flue-cured tobacco before and after topping

GENG Su-Xiang, WANG Shu-Hui, LIU Wei-Qun

2011, 19(6): 1250-1254. doi: 10.3724/SP.J.1011.2011.01250

Abstract(1203) PDF(1220)

Abstract:
A field experiment was conducted to study the effects of nitrogen (via caboratory analysis) on the activity of the key enzymes of carbon and nitrogen metabolism, phenylaprapanoid metabolism and their relative dry-matter accumulation in flue-cured tobacco before and after topping. Under zero-nitrogen treatment (N0), results showed that before topping, the activity of the key enzymes of carbon and nitrogen metabolism was low while that of phenylalanine ammonia-lyase (PAL) was relatively high. This facilitated photosynthetic carbon to apt to the accumulation of sucrose, starch and polyphenols. Accumulation intensity of nitrogenous compounds was also low. The activity of the key enzymes of carbon and nitrogen metabolism was higher under normal nitrogen treatment (N1) than those under N0. However, the intensity of nitrogen metabolism was remarkably higher. Carbon fixation in tobacco leaf preceded nicotine accumulation and pigment concentration was generally high. The activity of the key enzymes of carbon and nitrogen metabolism was high with harmonious carbon and nitrogen metabolism under normal nitrogen plus cake-fertilizer (N2). While starch accumulation was delayed, pigments contents were high. Accumulated polyphenol substances and nicotine were between those of N0 and N1 treatments. The activity of all key enzymes activities rose shortly after topping, with consistent levels of change. Whereas leaf tobacco contents of free ammonia and pigments decreased, that of nicotine increased. Nicotine content was highest under cake-fertilizer conditions (N2). The findings suggested that nitrogen application influenced harmonious degree between carbon and nitrogen metabolism, and fates of accumulated tobacco elements. Thus nitrogen application may control the direction of tobacco leaf metabolism, and furthermore change the quality and style of tobacco leaf.

Effect of microbial organic fertilizer on seedling growth, yield and quality of flue-cured tobacco

TENG Gui-Xiang, QIU Hui-Zhen, ZHANG Chun-Hong, ZHANG Wen-Ming, LIU Xing, HE Xiu-Cheng, HU Juan

2011, 19(6): 1255-1260. doi: 10.3724/SP.J.1011.2011.01255

Abstract(1472) PDF(1193)

Abstract:
Low quality and severe virus disease limit flue-cured tobacco production in the Loess Plateau of East Gansu Province. The effects of microbial organic fertilizer on tobacco growth, yield, quality and soil micro-organism were determined in a field trial. The field trial involved nursery and transplanted field cultivation where the effects of microbial organic fertilizer on local flue-cured tobacco production were investigated. Results showed that application of microbial organic fertilizer (T2) in nurseries significantly promoted tobacco growth and soil micro-organism population, which strengthened seeding vitality. Compared with T1 (chemical fertilizer), dry weight of max leaf and shoot increased respectively by 41.9% and 90.1% in T2. Total root length, specific root length, root dry weight and root tip number also increased by 151.5%, 25.8%, 100.0% and 286.0% in T2. Micro-organism count in T2 nursery soils increased. Specifically, actinomyce numbers rose significantly by 194.7% in T2 over T1, increasing disease resistance. Furthermore, T2 significantly promoted yield, quality and economic benefits of flue-cured tobacco in transplanted fields. Yield, economic benefit and net income increased respectively by 23.2%, 46.5% and 12 363 Yuan·hm^-2 in T2 over T1. Mid-high grade leaf ratio also increased by 16%. Main chemical components such as K, total N, nicotine, protein, sugar and schmuck were in the range of high-quality tobacco. Specifically, Middle-lower part leaf K content exceeded 3%, which signified high quality tobacco.

Effect of fertilization on yield, net income and soil environment in Qingdao protected vegetable production systems

GAO Jun-Ling, SONG Chao-Yu, WANG Yu-Jun, TANG Ji-Wei, SUN Zhao-Fa, ZHANG Shu-Xia, LI Xiang-Yun, HE Jin-Ming

2011, 19(6): 1261-1267. doi: 10.3724/SP.J.1011.2011.01261

Abstract(1429) PDF(1219)

Abstract:
To increase fertilizer use efficiency, reduce fertilizer cost and limit environmental pollution by fertilization, the study on effects of fertilizer application on yield, net income and soil environment in protected vegetable production systems in Qingdao were conducted. The study showed that excessive use of nitrogen (N), phosphorus (P) and potassium (K) fertilizers in tomato and cucumber fields, with N, P₂O₅ and K₂O average annual application rates of 1 841.5 kg·hm^-2, 864.0 kg·hm^-2 and 1 978.7 kg·hm^-2 for cucumber; and 1 436.7 kg·hm^-2, 833.6 kg·hm^-2 and 1 643.7 kg·hm^-2 for tomato, respectively. Organic manure and chemical fertilizers were applied at relatively reasonable rates, suggesting that much attention had been paid to the use of organic manure. Annual N, P₂O₅ and K₂O application rates had significant effects on annual yield and net income. Linear equations adequately explained the relationships of yield, net income with fertilizer application rate in the region. Soil nitrate-N content increased with increasing annual application rate of N. The protected vegetable fields of 31.4% farmer household had high or relatively high nitrate-N contents. Soil available P also increased with increasing annual P₂O₅ application rate. Similarly, 74.3% farmer household' protected vegetable fields had high soil available P content. Protected vegetable soils apparently acidified, 68.6% farmer household' protected vegetable field soil was acid or subacid, showing acidifying tendency. The results suggested that N, P₂O₅ and K₂O application rates should drop. Also new techniques such as computerized fertilization, integrated water-fertilizer managements, bacteria treated straws, soil straw return, etc., should be popularized to ensure the development of sustainable protected vegetable production in Qingdao.

Effect of fertilization on photosynthetic characteristics of wheat flag leaf

LI Ling, WANG Hui-Xiao, ZHANG Yu-Ming, CAI Yan, LIU Li-Fang

2011, 19(6): 1268-1271. doi: 10.3724/SP.J.1011.2011.01268

Abstract(1490) PDF(1196)

Abstract:
Daily variations in net photosynthetic rate of wheat flag leaf under different N, P and K rates were observed by LI-6400. Four treatments — high N (300 kg·hm^-2) and K (75 kg·hm^-2) with low P (32.5 kg·hm^-2) (N4P2K2), high K without N and P (N1P1K2), high P (65 kg·hm^-2) without N and K (N1P3K1) and high N and P without K (N4P3K1) were used in the experiment. The results revealed differences among daily variations in net photosynthetic rate (P_n) of wheat flag leaf under different fertilization treatments. N4P2K2 treatment significantly promoted wheat flag leaf P_n. However, N4P3K1 treatment did not significantly promote wheat flag leaf P_n. Photosynthesis was generally weak in N1P1K2 and N1P3K1 treatments. Daily variations in flag leaf P_n under the same treatment but at grain filling, milky and mature stages were also compared. Difference in P_n among three main growth stages was highest under N1P3K1 treatment and lowest under N4P3K1 treatment, it was medium under N4P2K2 and N1P1K2 treatments. P_n was relatively high under N1P1K2 treatment at mature stage. This suggested that K fertilizer influenced daily variations in photosynthetic characteristics of wheat flag leaf at mature stage.

Influence of exogenous N resource on triploid Populus tomentosa leaf decomposition

SONG Yue-Qin, ZHAI Ming-Pu, JIA Li-Ming, DAI Hong-Jie

2011, 19(6): 1272-1276. doi: 10.3724/SP.J.1011.2011.01272

Abstract(1365) PDF(978)

Abstract:
Litter decomposition is important for nutrient cycle in terrestrial ecosystems. Released nutrients by litter decomposition are critical for particularly fast-growing and high-yield pulp forests. Delays in on-site nutrient release could limit forest productivity. It is therefore vital to accelerate the decomposition of leaf litter for the rapid release of needed nutrients in forest plantations. To determine ways of rapid litter decomposition and nutrient release, the effects of exogenous ammonium nitrogen, nitrate nitrogen and mixed nitrogen on triploid P. tomentosa leaf decomposition were determined in a laboratory study. The results showed significant differences in the rates of decomposition of triploid P. tomentosa leaf under the different nitrogen resources. Leaf decomposition significantly accelerated under exogenous ammonium nitrogen. Compared with the control (27.4%), leaf decomposed rates under exogenous ammonium nitrogen, mixed nitrogen and nitrate nitrogen resources were 46.0%, 30.0% and 28.8%, respectively, after 140 d decomposition. The fitting results with Olson exponential equation showed that the times for 50% and 95% leaf decomposition under exogenous ammonium nitrogen, mixed nitrogen and nitrate nitrogen resources were 175 d, 316 d, 301 d and 781 d, 1 238 d, 1 627 d, which were shortened by 49.7%, 9.2%, 13.5% and 52.0%, 23.9%, 14.1%, compared with the control, respectively. There remarkable differences in released main nutrients of litter decomposition under exogenous ammonium nitrogen, mixed nitrogen and nitrate nitrogen resources. K content decreased with increasing degree of decomposition, and was not influenced by exogenous nitrogen resource. However, N and P release was influenced by exogenous nitrogen resource. While the accumulation time of N and P shortened from 21 to 7 days, the degree of N accumulation dropped from 1.94 (under the control) to 1.44 (under exogenous nitrogen) times of initial N concentration. The degree of P accumulation also dropped from 2.98 (under the control) to 1.98 (under exogenous nitrogen) times of initial exogenous P concentration. This suggested that exogenous nitrogen improved on-site productivity via accelerated leaf litter decomposition and N, P release, which in turn shortened the decomposition cycle of triploid P. tomentosa leaf litter.

Effect of soil factors on quality and style of flue-cured tobacco in Qujing District, Yunnan Province

XU Zi-Cheng, DU Juan, XIE Yan, XU Qing-Quan, LIU Jia-Hong, XIA Chen, XIANG Bo-Ka

2011, 19(6): 1277-1282. doi: 10.3724/SP.J.1011.2011.01277

Abstract(1396) PDF(1273)

Abstract:
Aroma quality evaluation methods were used to classify flue-cured tobacco into three aroma groups ― fen, moderate and enriched flavors. Depending on aroma score range (4~5, 2~4 and 0~2), the fen-flavor flue-cured tobacco was further classified into prominent fen-flavor, moderate fen-flavor, and weak fen-flavor. The classification focused on the effect of soil factors on fen-flavor aroma quality of flue-cured tobacco, with the aim of establishing reliable reference for tobacco material utilization. Grey relational analysis (GRA) was used to analyze the relationship between aroma characteristics of fen-flavor flue-cured tobacco and soil factors. Among ecological factors, little work has been done on how soil influences the aroma and taste of tobacco leaf. To this end, 973 samples of soil and flue-cured leaf were sampled in tobacco-growing fields in nine counties in Qujing District, Yunnan Province. While the collected soil samples were tested for fertility index, the corresponding tobacco leaves were tested for chemical components and aroma/taste quality. The results showed that prominent fen-flavor flue-cured tobacco had good aroma quality including rich aroma volume, less offensive/irritating odor, moderately lasting flavor, and small taste concentration and physiological strength. Prominent fen-flavor flue-cured tobacco agglomeration ability, sweetness and softness were significantly higher than those of moderate and weak fen-flavor flue-cured tobacco. Also the differences in the characteristics of fen-flavor flue-cured tobaccos in different soil types were significant. The characteristics of fen-flavor flue-cured tobacco from red soils were the strongest, followed by that from rice soils. Fen-flavor scores of flue-cured tobaccos from both red and rice soils were significantly higher than those from alluvial soils, yellow earth and purple soils. Furthermore, there were no significant differences among flue-cured tobaccos from alluvial soils, yellow earth and purple soils. Available phosphorus and potassium contents of red soils were relatively high. In red soil, 76.33% of total samples characterized as prominent fen-flavor, the proportion of tobacco with weak fen-flavor characteristics was highest in alluvial soils. Soils with tobacco of prominent fen-flavor had suitable pH and comparatively low contents of organic matter, total nitrogen and alkaline hydrolytic nitrogen. However, they had significantly higher contents of total phosphorus and potassium, and available potassium and iron than those with tobacco of weak fen-flavor. GRA also showed that the highest relational degree of aroma was with total phosphorus content, followed by total nitrogen content. Implicitly, soil factors such as available iron, magnesium and potassium contents and alkali-hydrolysis nitrogen strongly affected aroma of flue-cured tobacco. Furthermore, there was a significant correlation between the strength of fen-flavor characteristics and flue-cured tobacco variety. Cultivars such as the “Yunyan 87” and “K326” used in the study had evidently higher scores than the others.

Effect of added straw carbon on soil microbe and protozoa abundance

ZHANG Si-Hai, CAO Zhi-Ping, HU Chan-Juan

2011, 19(6): 1283-1288. doi: 10.3724/SP.J.1011.2011].01283

Abstract(1539) PDF(1443)

Abstract:
Driven by economic profits, the area of vegetables grown under plastic-film greenhouse has rapidly increased in recent years in China. Specific environmental conditions in plastic-film greenhouses could cause severe root-knot nematode disease. Hence a greenhouse pot experiment was conducted to study the effects of added straw carbon on soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and soil protozoa abundance. In the experiment, independent cultivation methods and selected tomato crops were used in a 3-gradient additive [1N (2.08 g·kg^-1), 2N (4.16 g·kg^-1) and 4N (8.32 g·kg^-1)] of winter wheat straw. Two sets of experiments were set up with respective tomato growth durations of 6 and 4 months. Based on the study, the order of abundance of MBC, MBN and protozoa was 4N>2N>1N>CK. Wheat straw carbon significantly enhanced MBC, MBN and protozoa abundance and protozoa community structure. Flagellate and amoeba were in vast proportions of soil microbial abundance, respectively accounting for 29.44% and 66.19%. Ciliates accounted for only 4.37% of total soil microbial abundance. With increasing cultivation period, soil protozoa abundance increased while soil MBC and MBN decreased under the same additive amount of wheat straw carbon. Under the same cultivation period, MBC, MBN, MBC/MBN ratio and soil protozoa abundance increased with increasing amount of added wheat straw carbon.

Effects of soil amendments on rhizosphere microbial number, soil enzyme activity and yield of continuous cropped American ginseng

SHU Xiu-Li, ZHAO Liu, SUN Xue-Zhen, PING Hua, PAN Li-Gang, WANG Jing

2011, 19(6): 1289-1294. doi: 10.3724/SP.J.1011.2011.01289

Abstract(1686) PDF(1569)

Abstract:
The continuous cropping of medicinal plants often resulted in deterioration of plant growth, decrease of plant resistibility to adversity, serious occurrence of disease and pest injury, and reduction of yield and quality. Numerous studies had found continuous copping obstacle in American ginseng cultivation, which restricted the sustainable development of American ginseng production. To explore the feasible routes of suppressing the barriers of continuous cropping of American ginseng, the paper systematically studied soil chemical properties, enzymes activities, rhizosphere microbial community and yield of continuously copped American ginseng through a randomized block experiment. Three soil amendments [hydrated lime, effective microorganisms (EM) and biogas slurry] in three application rates respectively were used in the experiment. The results showed that low-concentration of hydrated lime, middle-concentration of EM and high-concentration of biogas slurry were the most favorable conditions for American ginseng yield. The numbers of main groups of soil microorganisms and urease activity were significantly decreased, while soil pH significantly increased under hydrated lime treatments. The numbers of main groups of soil microorganisms, soil organic matter and nutrients contents were significantly improved (P < 0.05), and urease and polyphenoloxidase activities increased under biogas slurry and EM treatments. Correlation analysis showed significantly positive correlation between number of soil bacteria and activities of sucrase and polyphenoloxidase (r=0.895^**, 0.808^**). The numbers of fungi and actinomycetes were significantly and positively correlated with invertase, urease and polyphenoloxidase activities (r=0.932^**, 0.769^**, 0.840^**; 0.837^**, 0.891^**, 0.797^**). Bacteria number and soil organic matter content were significantly correlative (r=0.863^**). The results indicated that rhizosphere soil microorganisms were closely correlated with soil chemical properties, enzymes activities in continuous cropping system of American ginseng. Soil amendments in proper concentrations provided appropriate anti-continuous-cropping soil environments for American ginseng pro-duction.

Effect of tillage pattern on soil greenhouse gases (CO₂, CH₄ and N₂O) fluxes in semi-arid temperate regions

WANG Jing, CAI Li-Qun, ZHANG Ren-Zhi, WANG You-Ling, DONG Wen-Jun

2011, 19(6): 1295-1300. doi: 10.3724/SP.J.1011.2011.01295

Abstract(1620) PDF(1276)

Abstract:
Different tillage methods and crop rotations were experimented in Lijiabao Town of Dingxi City, Gansu Province and soil carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) fluxes measured using carbon dioxide analyzer and static chamber-gas chromatographic techniques. Analysis of the four tillage methods [tillage without straw or plastic film mulching (T), no-tillage without straw or plastic film mulching (NT), no-tillage with straw mulching (NTS) and tillage with straw mulching (TS)] showed that soils with spring wheat and pea were sources of atmospheric CO₂ and N₂O, sink of CH₄ during crop growth seasons. In spring wheat fields, the mean values of soil CO₂ flux (μmol·m^-2·s^-1) were 0.203 6, 0.221 2, 0.241 8 and 0.224 9 for T, NT, NTS and TS treatments, respectively. The mean values of soil CH₄ flux (mg·m^-2·h^-1) were -0.041 6, -0.078 0, -0.081 8 and -0.053 7 and those of soil N₂O flux (mg·m^-2·h^-1) were 0.089 1, 0.069 2, 0.046 1 and 0.065 6 for T, NT, NTS and TS treatments, respectively. In pea field, the mean values of soil CO₂ flux (μmol·m^-2·s^-1) were 0.273 6, 0.261 6, 0.218 1 and 0.236 0 for T, NT, NTS and TS treatments, respectively. The mean values of soil CH₄ flux (mg·m^-2·h^-1) were -0.055 0, -0.073 7, -0.066 2 and -0.054 5 and those for soil N₂O flux (mg·m^-2·h^-1) were 0.123 4, 0.084 7, 0.080 6 and 0.035 0, respectively. Compared with T, NT and TS, NTS retarded CO₂ and N₂O emission and enhanced CH₄ assimilation. Based on the study, NT, NTS and TS conservation tillage methods were efficient for retarding greenhouse gas emission. CO₂ fluxes increased with increasing soil moisture and temperature in spring wheat field, and CH₄ uptake fluxes increased with increasing soil moisture, but reduced with increasing soil temperature. A significant positive correlation was noted between CO₂ flux and soil moisture in pea field. Similarly, a significant positive correlation was observed between N₂O emission and soil temperature in pea and spring wheat fields.

Characteristics of soil organic carbon and nitrogen distributed in different density fractions of mollisols under long-term continuous cropping and natural restoration

YOU Meng-Yang, HAN Xiao-Zeng, LI Hai-Bo, LU Si-Jia, LIANG Yao

2011, 19(6): 1301-1306. doi: 10.3724/SP.J.1011.2011.01301

Abstract(1247) PDF(1134)

Abstract:
Land use change has a long-term impact on terrestrial ecosystems, resulting in variations in soil carbon pool and carbon cycle. This has triggered a contentions research on the state of soil organic carbon. A long-term experiment was conducted at the National Observation Station of Hailun Agroecosystem, Chinese Academy of Sciences. The experiment included three land use types in five treatments ― i.e., farmland (continuous cropped maize, continuous cropped soybean and continuous cropped wheat), grassland and bare-land, with mollisol as the soil type. The objective of the study was to determine how land use influences the characteristics of soil organic carbon (SOC) and nitrogen distribution among different density fractions (light and heavy). The results showed no significant differences in total SOC among the three farmland treatments. The difference in FLF (free light fraction) SOC content between 0~10 cm and 10~20 cm farmland soil layers was significant (P < 0.05). Whereas FLF SOC mainly accumulated in the 0~10 cm soil layer under continuous cropped soybean treatment, it mainly accumulated in the 10~20 cm soil layer under continuous cropped wheat treatment. There were also no significant differences in OLF (occluded light fraction) SOC content among the farmland treatments. Accumulated FLF and HF (heavy fraction) were critical for net enhancement of TOC (total organic carbon) and TN (total nitrogen). OLF lessly influenced TOC and TN accumulation. The distribution characteristics of soil nitrogen in different density fractions were similar to those of SOC. In terms of C/N ratio, there was significant negative correlation between FLF and OLF. TOC and TN were significantly higher in grassland than in farmland and bare-land treatments. FLF SOC, OLF and HF contents in grassland were much higher than in farmland and bare-land treatments. Vegetation conversion caused not only soil organic matter redistribution, but also carbon and nitrogen sequestration variation in mollisols.

Soil evaporation under sole cropping and intercropping systems and the main driving factors

CHAI Qiang, YU Ai-Zhong, CHEN Gui-Ping, HUANG Peng

2011, 19(6): 1307-1312. doi: 10.3724/SP.J.1011.2011.01307

Abstract(1258) PDF(1145)

Abstract:
Several studies have shown that compared to sole cropping, well managed intercropping improves agricultural resources utilization efficiency, include radiation, nutrient, water and land. However, high productivity of traditional intercropping system has mainly depended on high input of agricultural resources. With severe water shortages in recent years (especially in mainland China), intercropping system of farming has continuously declined. The scientific challenge therefore is the determination of water consumption characteristics and systematic development of high-efficiency water-saving theories and technologies of intercropping system. In this study, a field experiment (comprising of wheat or maize sole cropping and wheat-maize intercropping systems under three different irrigation schemes) was conducted in 2008 in the Hexi Corridor oasis region. The study investigated soil evaporation characteristics and associated driving factors under the different cropping systems and treatments with the aim of laying the scientific basis for developing optimized irrigation techniques. The study showed that evapotranspiration (ET) under wheat-maize intercropping was 41.44%~47.15% higher than the average ET under wheat and maize sole cropping systems. Total soil evaporation (E) of intercropping system was significantly higher than that of sole cropping systems. However, daily E of intercropping system was significantly lower than that of maize sole cropping system. Also compared with sole cropping system of maize, wheat-maize intercropping system enhanced E/ET ratio. With increasing irrigation, total water consumption increased significantly under intercropping. However, the difference in water consumption between two adjacent irrigation treatments under sole cropping systems of wheat and maize was insignificant. The difference in E of sole cropping maize and intercropping wheat-maize was insignificant for different irrigation schemes. It then implied that high water consumption of intercropping system was mainly driven by high transpiration. Average daily E was positively correlated with water content in the 0~30 cm soil profile, temperature in the 0~25 cm soil profiles and average leaf area index of the crops. High E was driven by high water content in the 0~30 cm soil profile and temperature in the 0~25 cm soil profile of maize sole cropping system. On the average, wheat-maize intercropping not only reduced water consumption but also increased water and land use efficiency compared to sole cropping. This cut down wasteful crop transpiration, which was an effective means of water-saving irrigation.

Comparative study on yield and economic benefits of rape under different planting and mulching patterns

ZHANG Dong-Yu, ZHAO Dong-Xia, YAN Zhi-Li, NIU Jun-Yi, FAN Hong-Wei, ZHANG Yan-Ming, YU Xing-Fang

2011, 19(6): 1313-1318. doi: 10.3724/SP.J.1011.2011.01313

Abstract(1696) PDF(1288)

Abstract:
To establish drought-resistant cultivation techniques of rape (Brassica napus) in dry mountainous lands of the West China, the characteristics, yield and economic benefits of rape under five mulching/planting treatments were investigated in an field experiment using conventional cultivation as the control. The treatments included furrow planting with plastic-film-covered ridges (FURP), flat planting with half plastic-film mulch (FLHP), flat planting with complete plastic-film mulch (FLOP), flat planting with wheat-straw mulch (FLW) and furrow planting with plastic-film-covered furrows/ridges (FUFRP). Result showed that FLOP, FUFRP, FURP and FLHP significantly increased rape plant height, stem diameter and length of main inflorescence. While FLOP and FUFRP promoted first branching of rape, FLHP, FURP and FLW inhibited it. The five mulching/planting treatments unduly affected secondary branching of rape. Whereas FUFRP, FLOP, FURP and FLHP increased pod number per plant; FURP, FLW and FLHP increased grain number per pod. There were notable negative effects of FUFRP, FLOP, FURP and FLW on the 1000-grain weight of rape. Actual yields of FUFRP, FLOP and FURP were 2 111.25 kg·hm^-2, 2 017.95 kg·hm^-2 and 1 934.70 kg·hm^-2, respectively representing an increase of 52.16%, 45.44% and 39.44% over conventional cultivation. Net economic benefits of FUFRP, FLOP and FURP were 1 985.85 Yuan·hm^-2、1 868.55 Yuan·hm^-2 and 1 495.20 Yuan·hm^-2 which were respectively 2.22, 2.03 and 1.43 times higher than those of conventional cultivation. Yields and economic benefits of FLHP and FLW were significantly lower than those of conventional cultivation. The study suggested that in dry mountainous lands of the West China, FUFRP, FLOP and FURP were suitable mulching and planting patterns for rape cultivation. In terms of yield and economic benefits, the outputs of these cultivation patterns were higher than those of the other patterns of cultivation.

Changes in and correlation analysis of quality indices of hydroponic lettuce under short-term continuous light

ZHOU Wan-Lai, LIU Wen-Ke, WEN Jing, YANG Qi-Chang

2011, 19(6): 1319-1323. doi: 10.3724/SP.J.1011.2011.01319

Abstract(1630) PDF(1372)

Abstract:
Nitrate easily accumulates in vegetables (especially leaf vegetables) and poses serious health hazard if excessively ingested. Light is a critical environmental factor influencing plant nitrate content. In this study, changes in contents of nitrate, soluble sugar and vitamin C (Vc) in hydroponic lettuce under 72 h continuous light and their correlation were analyzed. The aim of the study was to explore quality control measures of vegetables grown in controlled environments. The study showed that nitrate content in both leaf blade and petiole decreased significantly with variational rate in different time. Nitrate content in blade and petiole tended to steady after 24 h and 48 h continuous light respectively, while soluble sugar and Vc contents increased rapidly at a roughly constant rate and showed little trend of slowing down. There was no significant difference between blade and petiole soluble sugar contents. However, blade Vc content was much higher than that in petiole. Both in blade and petiole, nitrate content was significantly negatively correlated with soluble sugar and Vc contents. The results showed that short-term exposing to continuous illumination was suited to produce high quality lettuce with perfect unity of low nitrate accumulation and high soluble sugar and Vc contents.

Effect of drip irrigation pattern on wine grape growth, yield, photosynthesis and water use efficiency in arid desert regions

LI Zhao-Nan, LI Wei, LIU Ji-Liang, NIU Rui-Xue, QIN Yu

2011, 19(6): 1324-1329. doi: 10.3724/SP.J.1011.2011.01324

Abstract(1594) PDF(1775)

Abstract:
A field experiment was conducted in Hexi Corridor arid desert region, Gansu Province, to study the effects of drip irrigation amount on wine grape growth, photosynthesis, water use efficiency, yield and fruit quality under plastic-film and no mulching. The study revealed significant enhancement of primary and secondary new shoot length and main grape vine diameter with increasing drip irrigation amount. Even under low drip irrigation, better grape growth with higher above-3 index was noted in plastic-film mulching than in no plastic-film mulching. Under different drip irrigation amounts with or without plastic-film mulching, the rates of daily net photosynthetic rate, transpiration rate and stomatal conductance tracked a similar trend of continuous decline. However, the rate of intercellular CO₂ concentration initially declined and then increased. The photosynthesis indices of plastic-film mulching with 240 mm (T1) and 300 mm (T2) irrigation treatments were not only lower than those with 360 mm (T3) and 420 mm (T4) irrigation treatments, but also that of no mulching with 360 mm (CK) irrigation treatment. T1 water use efficiency was the highest among the treatments. Based on regression analysis, the correlation between intercellular CO₂ concentration and soil moisture was the most significant. This was followed by that between intercellular CO₂ concentration and stomatal conductance, then net photosynthesis rate and then transpiration rate. Grape yield of treatments with plastic-film mulching were higher than no-mulching treatment. Sugar content of grape fruits was highest under no-mulching treatment, followed by T1 treatment. T1 was the optimal treatment for high grape quality and yield production, with the most efficient water resource use.

Effect of water condition on hyperspectral and red-edge characteristics of tobacco leaf

JIA Fang-Fang, MA Xin-Ming, LI Chun-Ming, LIN Shi-Zhao, LI Yan-Qiang

2011, 19(6): 1330-1335. doi: 10.3724/SP.J.1011.2011.01330

Abstract(1573) PDF(1560)

Abstract:
Red-edge characteristics of two cultivars of tobacco under different water treatments were analyzed by measuring leaf spectra with ASD Fieldspec HH. The relationship between red-edge parameters and physiological indices of tobacco was also determined. The results showed notable differences between leaf spectral reflectance of the two cultivars under different water treatments. However, the trend of change in spectral reflectance was similar in the two cultivars. While near-infrared band reflectance increased with increasing soil moisture during root elongation and vigorous growth stages, it decreased at mature stage. Leaf spectral reflectance was highest at vigorous growth stage. Though first differential spectra of red-edge of tobacco leaf showed similar tends, first derivative spectra were significantly different under different treatments. Red-edge position shifted from short to long wavelength with decreasing soil moisture, causing red shift during tobacco entire growth period. While the slope and area of red-edge increased at root elongation and vigorous growth stages (characterized as red shift), they shifted from long to short wavelength at mature stage (characterized as blue shift). The correlations of red-edge position with physiological indices of tobacco leaf were more significant than those with red-edge slope and area. There were significant correlations among red-edge position with contents of chlorophyll a, chlorophyll b, chlorophyll a+b and carotenoid; leaf fresh-weight, leaf dry-weight, leaf area and leaf moisture contents. There were also significant positive correlations among red-edge slope and area with chlorophyll a, chlorophyll b, chlorophyll a+b, carotenoid and leaf moisture contents. The correlation between red-edge area and leaf dry-weight was negative.

Effect of ridge/furrow rain harvesting on soil moisture, bulk density and porosity in Medicago sativa field

KOU Jiang-Tao, SHI Shang-Li, WANG Qi, YIN Guo-Li

2011, 19(6): 1336-1342. doi: 10.3724/SP.J.1011.2011.01336

Abstract(1211) PDF(1041)

Abstract:
Experiment on rain harvesting under dry farming was conducted to determine the effects of ridge/furrow width ratio and mulching modes on soil moisture, soil bulk density and porosity in Medicago sativa cultivation fields. Based on the study, average water loss in the 0~120 cm soil layer was lower by 28.43 mm for plastic film covered ridges and 13.61 mm for compacted bare soil ridges than CK (flat field). The increase rate of rain water storage was 59.03%~99.27% in plastic film covered ridges with runoff generation efficiency of 53.43%~91.72% during the whole rainy season. From early April to early June (when was prior to 2009 rainfall collection period), the increase rate of rain water storage in compacted bare soil ridges was 1.92%~2.74% with corresponding runoff generation efficiencies of 1.71%~2.55%. From mid June to late September (when was mid-to-late rainfall collection period), the increase rate of rain water storage (8.85%~36.77%) and runoff generation efficiency (8.01%~35.82%) increased significantly. The increase rate of rain water storage and runoff generation efficiency on both plastic-film covered and soil-compacted ridges increased with increasing ridge surface area. However, increment in the increase rate of rain water storage and runoff generation efficiency on plastic-film covered ridges was remarkably higher than that on compacted bare soil ridges. Soil bulk density in the 0~40 cm soil layer significantly dropped in ridge/furrow rain harvesting system. The degree of drop in soil bulk density in plastic film covered ridges was higher than that in compacted bare soil ridges in the 0~20 cm soil layer. Accordingly, soil porosity in the 0~40 cm soil layer significantly increased in ridge/furrow rain harvesting system. Also the degree of rise in soil porosity in plastic film covered ridges was larger than that in compacted bare ridges in the 0~20 cm soil layer.

Effect of brackish water on winter wheat seed germination and seedling growth

SHI Chang-Hai, LI Yu-Xin, ZHAI Hong-Mei, YANG Jing, LI Dong-Xiao, DONG Bao-Di, QIAO Yun-Zhou, LIU Meng-Yu

2011, 19(6): 1343-1347. doi: 10.3724/SP.J.1011.2011.01343

Abstract(1415) PDF(1177)

Abstract:
Despite the abundance of brackish water in the Bohai Sea region, seasonal (winter and spring) drought is persistent in north China. A pot experiment was therefore conducted to explore the use of brackish water in irrigation before winter wheat sowing or in winter irrigation. Three winter wheat cultivars (irrigated/dry land cultivar “Shijiazhuang 8”, dry land cultivar “Jinmai 47” and salt-resistant cultivar “Xiaoyan 81”), ecologically adapted to the North China, were used in the study. The modes of seed germination, seedling growth and development were analyzed. The results suggested that “Shijiazhuang 8” and “Xiaoyan 81” seed germination was not affected by brackish water irrigation. However, the energy and rate of germination of “Jinmai 47” dropped significantly. Germ fresh weights of the 3 cultivars were irresponsive to brackish water treatment. While wheat root growth was retarded, shoot growth was enhanced by brackish water irrigation. Root/shoot ratio of “Shijiazhuang 8”, “Jinmai 47” and “Xiaoyan 81” decreased by 51.6%, 36.8% and 32.3%, respectively. The corresponding contents of chlorophyll, however, increased by 38.5%, 12.9% and 26.0%. On the average, brackish water enhanced shoot growth of winter wheat. Water use efficiencies of the 3 winter wheat cultivars increased under brackish water irrigation. The high water use efficiency was driven mainly by limited water consumption and saline water uptake due to retarded root growth.

Characteristics of landscape geochemistry in Karamay artificial carbon-sink forests

DING Yu-Hua, WANG Rang-Hui, NING Hu-Sen

2011, 19(6): 1348-1353. doi: 10.3724/SP.J.1011.2011.01348

Abstract(1354) PDF(1210)

Abstract:
Karamay artificial carbon-sink forest is located in the southern margin of Gurbantunggut Desert, where soil salinization is a severe ecological problem. With adequate knowledge on the patterns of soil soluble salts/ions distribution, mechanisms of change, chemical constituents of groundwater and varied characteristics of landscape patterns, saline soils can be rationally utilized and ecological agro-forestry efficiently developed. This paper aimed to lay the theoretical basis for ameliorating soil salinity and controlling desertification via analyzing the characteristics of Karamay landscape geochemistry. Using monitoring field data for soil soluble salt, groundwater salinity and vegetation cover in Karamay artificial carbon-sink forest, the characteristics of landscape geochemistry were analyzed via descriptive statistics and correlation analysis. The results showed great variation in contents of Cl^-, SO₄^2-, Ca²⁺ in 0~80 cm soil, while less variation in salinity and salt ions contents in 80~100 cm soil layer was found. Soil salinity increased with increasing soil evaporation resulting in severe salt accumulation in surface soils of Karamay carbon-sink forest. Sulfate was the dominant salt in study area, which consisted mainly of soluble SO₄^2- and Na⁺ and K⁺ salts. With the exception of HCO₃^-, variations in groundwater salinity and the related compounds exhibited strong variation. Cl^-, SO₄^2-, Na⁺ and K⁺ were the main elements of groundwater mineralization, and significant linear correlations were noted among salinity and these ions. The groundwater chemical type was Cl·SO₄-Na. Forest protection ameliorated soil salinity. Although the dynamics of soil salinity varied from forest to forest, salinity (more for SO₄^2- salts) dropped after planting forests. Furthermore, soluble total salts significantly dropped with increasing age of the Russia poplar forest.

Dynamics of groundwater table and soil desalination of platform fields in coastal wasteland

DONG Xiao-Xia, WANG Xue-Jun, LIU Zhao-Hui, SUN Ze-Qiang, ZHENG Dong-Feng

2011, 19(6): 1354-1358. doi: 10.3724/SP.J.1011.2011.01354

Abstract(1392) PDF(1332)

Abstract:
In this study, 135 cm, 145 cm, and 175 cm high platform fields were built on coastal saline wastelands in the Yellow River Delta. The dynamics of groundwater table were monitored over a period of 2 years and changes in soil salt content after 5 years crop cultivation were determined, with natural saline wastelands as the control. The main objective of the study was to provide data-driven technical support for large-scale agricultural development in coastal saline soils. The results of the 2-year consecutive monitoring showed that the three platform fields effectively increased saline water table. Groundwater table in saline wastelands changed in the range of 0.65~2.10 m, while those in the three platform fields changed in the range of 2.20~3.63 m. Compared with saline wastelands, groundwater salinity of the three platform fields significantly increased. This suggested that salts in platform fields leached from soil profile to groundwater via both irrigation and rainfall. Salt content in the 0~30 cm soil layer was 4.90~7.33 g·kg^-1 in saline wastelands, which significantly dropped to <1.37 g·kg^-1 after platform field development and irrigation. Desalination ratio of the platform fields was 81.31%~89.05%. Salt content in the 0~120 cm soil layer of the platform fields was lower than those of saline wastelands after 5 years cultivation. The differences in soil salt content between platform field and control field in both 0~30 cm and 30~60 cm soil layers were significant. Soil profile salt content in the 135 cm and 145 cm platforms was <1.62 g·kg^-1. The results indicated that “platform field-deep ditch” was an effective engineering measure to ameliorate salinity in coastal wastelands. In terms of cost and effective area ratio, the 145 cm high platform field was recommended the best practice for coastal wasteland desalination.

Flaveria bidentis decomposition and residual body regeneration in soils

SONG Si-Wen, SHEN Zuo-Rui, NI Han-Wen, MA Ming-Ye, LI Zhi-Fang

2011, 19(6): 1359-1364. doi: 10.3724/SP.J.1011.2011.01359

Abstract(1362) PDF(1213)

Abstract:
Flaveria bidentis invasive plant is a malignant weed in cultivated lands and ecotones in the North China Plain (NCP). Herbicides used to eliminate this weed leave chemical residues on vegetables that have human healthy risks. This study investigated regeneration ability of cut/remaining parts of F. bidentis after hand weeding. Soil incubation was conducted to explore the degradation of dry F. bidentis straw containing 12.2 g·kg^-1 of nitrogen and compared with that of Trifolium repens green manure plant containing 23.3 g·kg^-1 of nitrogen. The aim was to learn the possibility of artificially weeded F. bidentis as a green manure. The results showed that regeneration percent of different parts of F. bidentis shoots was 10%~80%, and that of different remaining parts of the weed was 70%~100%. It was therefore recommended to remove F. bidentis residues (including left roots) from the fields. During 60 days of the soil incubation experiment, treatments with both F. bidents and T. repens straws showed the highest apparent daily net CO₂-C release in the first 10 days after incorporation. Thereafter, the apparent daily net CO₂-C release dropped and stabilized. Apparent net CO₂-C release in soils with F. bidentis straw was lower than that in soils with T. repens straw. Microbial biomass nitrogen content of F. bidentis straw treated soil was higher than those of T. repens straw treated and control soils. Also microbial biomass carbon content of F. bidentis straw treated soil was lower than that of T. repens straw treated soil, but similar to that of control soil. Within 20 days of soil incubation, F. bidentis straw exhibited mineral nitrogen fixation and mineral nitrogen re-release after 40 days. In conclusion, F. bidentis enhanced soil nitrogen and microbial biomass, which in turn improved soil fertility. Artificially weeded F. bidentis was usable as a form of green manure after inactivated treatment.

Effect of Ageratina adenophora (Spreng.) and Flaveria bidentis (Linn.) invasion on soil microbial community and Oryza sativa L. growth

LI Hui-Na, LIU Wan-Xue, WAN Fang-Hao

2011, 19(6): 1365-1371. doi: 10.3724/SP.J.1011.2011.01365

Abstract(1549) PDF(1441)

Abstract:
This study analyzed the differences in soil micro-ecology between alien invasive weeds and local plants to understand impacts of alien invasive plant on soil ecosystem. Two invasive plant species [perennial Ageratina adenophora (Sprengel) and annual Flaveria bidentis plants] and two native plant species (Digitaria sanguinalis and Salsola collina) were planted in a common garden, in which the same soil from a non-invaded farmland was used to eliminate the effect of different soil minerals on the variations in the four plant species. Then a greenhouse experiment was conducted to verify any effects of rhizospheric soil microbial communities of two invasive plants on the performance of native plants. In the field experiment, soil nutrient, soil microbial community after three months of plants growth were examined. Based on the common garden experiment, differences were noted in the effects of invasive and native plants on soil micro-ecology. A. adenophora drastically increased soil available N (39.80 mg·kg^-1), P (48.52 mg·kg^-1) and K. In particular, PLFA (phospholipids fatty acids) fingerprint spectrum suggested a higher increase in actinomycete contend in the exotic plants soils than in the native plants soils. The increase in bacteria and fungi count was highest in A. adenophora invading soils. Pot feedback experiment showed that alien weed invaded soils inhibited the growth of Oryza sativa. O. sativa plant height increased by 113% and 17% in ste-rilized F. bidentis and A. adenophora invaded soils compared with no-sterilized soils, respectively. The above results suggested that F. bidentis and A. adenophora destroyed micro-habitats of invaded soils and created new micro-ecology environment suitable for the growth of invasive plants by altering soil microbial communities.

Analysis of plant growth promoting rhizobacteria population in apple rhizosphere soils

GUO Hui, MAO Zhi-Quan, SONG Zhen, ZHANG Ben-Feng, QIU Nian-Quan, LIU Xun-Li

2011, 19(6): 1372-1378. doi: 10.3724/SP.J.1011.2011.01372

Abstract(1401) PDF(1095)

Abstract:
Apple replant disease (ARD) is a complex syndrome of young apple trees in replanted orchards that causes death of fine feeder roots, stunted tree growth and low yield. Analyzing changes in the number and species of plant growth promoting rhizobacteria (PGPR) in perennial apple tree (PAT) and replanted young tree (RYT) fields could lay theoretical basis for understanding the interactions among ARD and rhizosphere microbes. In this study, rhizosphere soil samples were collected in PAT and RYT fields in Changli, Hebei Province. Rhizosphere bacteria of interest in the study included azotobacter, phosphate-dissolving bacteria, potassium-dissolving bacteria and antagonistic bacteria. While rhizosphere azotobacter, phosphobacteria, potassium-bacteria were cultivated by the selective media plate cultivation method, antagonistic bacteria (with antagonistic activity against Rhizoctonia solani or Fusarium camptoceras) were isolated using the in vitro screening technique. For soil samples from both fields, microbe species and population examined by colony-forming unit (CFU) count. Also BOX Polymerase Chain Reaction (BOX-PCR) was used to fingerprint the different PGPRs. Total rhizosphere bacteria, azotobacter, phosphate-dissolving bacteria, potassium-dissolving bacteria and antagonistic bacteria were more abundant in PAT than in RYT fields. In PAT fields, potassium-dissolving bacteria were the most abundant, followed by phosphate-dissolving bacteria and then azotobacter. Antagonistic bacteria were the least abundant. In RYT fields, phosphate-dissolving bacteria were the most abundant, followed by potassium-dissolving bacteria and then azotobacter. Antagonistic bacteria were also the least abundant. Based on BOX-PCR fingerprints cluster analysis of PGPR, there were over 1.25 dissimilarities in both PAT and RYT fields. This somehow suggested close genetic evolutionary distance among the isolates. PGPR in PAT fields were divided into 79 clusters; including 18 azotobacter, 29 phosphate-dissolving bacteria, 19 potassium-dissolving bacteria and 18 antagonistic bacteria clusters at 0.25 BOX-PCR fingerprint dissimilarity. Similarly, PGPR in RYT fields were divided into 46 clusters; including 15 azotobacter, 19 phosphate-dissolving bacteria, 8 potassium-dissolving bacteria and 9 antagonistic bacteria clusters at 0.25 BOX-PCR fingerprint dissimilarity. Replanting therefore significantly influenced rhizosphere bacteria abundance in orchard fields. Higher PGPR population and biodiversity were noted in PAT than in RYT fields. While the indices of diversity, richness and evenness of azotobacter, phosphate-dissolving bacteria, potassium-dissolving bacteria and antagonistic bacteria were higher in PAT than in RYT fields, the reverse was true for dominance index. Based on the findings, abundant microbes existed in PAT fields and with complex and stable ecological distribution of microbial community. However, only less PGPR with great vitality colonized RYT fields and with simple rhizosphere microbial community structures.

Response of Vicia faba growth and soil enzyme activity to low molecular polyethylene added in soil

CAO Xiao-Wei, TAO Zong-Ya, LUO Xue-Gang, HAN Qing-Hua, CHEN Li-Ping

2011, 19(6): 1379-1385. doi: 10.3724/SP.J.1011.2011.01379

Abstract(1445) PDF(1340)

Abstract:
It is an important way for preventing “white pollution” to develop and promote environment-friendly biodegradable plastic film, which is holding back the development of agriculture. Compared with ordinary plastic film, biodegradable plastic film takes less time to degrade, and has low molecular weight residues, mainly linear low density polyethylene (LLDPE). The research into the effect of low molecular weight polyethylene (LMWPE) on crop growth and soil microenvironment was of great significance to promote use of biodegradable plastic film. In the experiment, we simulated natural conditions and LMWPE were added in different dosages to pot-soils in which horse bean (Vicia faba Linn.) were planted. Dosages of LMWPE were 0.028 g·kg^-1, 0.28 g·kg^-1, 1.40 g·kg^-1, 2.80 g·kg^-1, which were decided according to residue amounts in soils with 1, 10, 50, and 100 years continuous plastic film mulching. The plant height, leaves number and pod number, as well as the activities of urease, peroxidase and sucrase in soil were measured during whole growth period of horse bean. During horse bean growth period, plant height, leaf number and activities of urease, peroxidase of soil under LMWPE treatments were increased compared with those under CK₁ (cultivation of horse bean without LMWPE). The more LMWPE were added, the more significant the effects were. But soil invertase activities and horse bean pod number were not significantly affected by LMWPE. Formation and growth of horse bean roots impacted activities of three soil enzymes significantly. Soil enzyme activities were significantly correlated with plant height, leaf number of horse bean, but not with pod number. It showed that added LMWPE in soil had activating effects on horse bean growth and soil enzymes activities. 2.80 g·kg^-1 LMWPE showed most obviously effects.

Effects of environmental materials on maize growth and soil remediation of Pb and Cd contaminated soils

PENG Li-Cheng, HUANG Zhan-Bin, SHI Yu, SUN Hua-Jie, SHEN Chen, CHEN Wei, ZHANG Xiao-Ming

2011, 19(6): 1386-1392. doi: 10.3724/SP.J.1011.2011.01386

Abstract(1462) PDF(1352)

Abstract:
Application of environmental materials is a vital remedial measure of heavy metal lead (Pb) and cadmium (Cd)) contaminated soils. To explore the effects of environmental materials on plant growth and quality and to enhance remediation of Pb and Cd contaminated soils, a pot experiment was setup in greenhouse conditions. The experiment analyzed soil properties, growth and quality as well as Pb and Cd contents of maize (Zea mays L.) in Pb-Cd contaminated soils. Different environmental treatments, including single environmental materials treatments [e.g., humus (HA), polymers (SAP), coal-derived composites (FM) and powder minerals (FS)], and composite treatments of environmental materials were selected in heavy metal Pb and Cd contaminated soils. The results indicated that F22 (FM+SAP), F23 (FS+SAP) and F32 (HA+SAP+FS) composite treatments promoted stronger maize growth at seedling stage than that of the control. Maize crude ash in all the treatments with environmental materials was less than that of the control. Also maize crude starch in single environmental material treatments was higher than that in composite environmental material and control treatments. By comparison, single FM and combined F33 (SAP+FM+FS) and F4 (HA+SAP+FM+FS) treatments had a significant inhibition effect on maize Pb uptake in Pb-Cd contaminated soils. Similarly, single FM and FS and composite F33 (SAP+FM+FS) environmental materials treatments had a significant prohibition effect on maize Cd uptake in Pb-Cd contaminated soils. Thus the application of environmental materials could improve soil physical and chemical properties and inhibited crop heavy metal uptake.

Growth and F absorbing of rice under F and Al-F interaction

LI Yang-Yang, LIU Jin-Hua, WANG Hong-Bin, JIANG Yi-Mei, ZHAO Lan-Po

2011, 19(6): 1393-1398. doi: 10.3724/SP.J.1011.2011.01393

Abstract(1186) PDF(1076)

Abstract:
This paper researched the rule of fluoride absorbing of rice and the influence of aluminum sulfate on the absorption of fluoride by rice plant under different fluoride concentrations through a pot experiment. The results showed that, in the treatment of applying fluoride solely, there was a significant positive correlation between concentration of applied fluoride and fluorine content of rice plant indicating an extravagant absorption of fluorine by rice plant. The content of fluorine in rice plant decreased with the growing time, which resulted from the decreased fluorine absorption. No significant difference in the growth of rice plants was observed among different treatments of applied fluoride amount, while the number of tillers was significantly reduced with increasing of the concentrations of applied fluoride. Under Al-F interaction, the order of fluorine content in various parts of rice plant was hull > rice > root > stem and leaf. This may be related with different fluoride absorbing parts and forms of fluoride absorbed. Under no aluminum sulfate, the contents of fluorine in different parts of rice plant already had showed decreasing tendency with the growing time. This tendency was enhanced by additional application of aluminum sulfate. However, greater difference in fluorine-reducing effects existed among different rice growth times even under the same treatment of aluminum sulfate. So, the proportion of aluminum and fluorine, Al-F interacting time to achieve the best effect of reducing fluoride should be further researched.

Effect of heavy metal Cu on compost materials property and oxidoreductase activity during pig waste composting

ZHANG Wei-Juan, GU Jie, LIU Qiang, GAO Hua, GUO Xing-Liang

2011, 19(6): 1399-1404. doi: 10.3724/SP.J.1011.2011.01399

Abstract(1550) PDF(1536)

Abstract:
Changes in polyphenoloxidase and dehydrogenase activities, temperatures, pH and E4/E6 ratio of humic acids during aerobic fermentation and thermophilic aerobic state of compost materials during pig waste composting were determined in this study. The aim of the study was to lay the fundamental groundwork for learning biological behaviors during composting of heavy metal Cu-treated compost. Pig manure and straw were used as experimental compost materials in three treatments — low content (100 mg·kg^-1) heavy metal Cu treatment (A1), high content (500 mg·kg^-1) heavy metal Cu treatment (A2) and non-heavy metal Cu treatment (CK). The results showed that temperature was higher in CK than in A1 and A2 treatments during compost cooling phase. The lowest pH and average E4/E6 of CK were 5.94 and 3.88. The highest pH and average E4/E6 were 8.85 and 3.68 for A2 in the study. Temperature rise was fastest in A1, with higher temperatures and longer high temperature duration than in the other treatments. This effectively destroyed pathogens and reached harmless conditions at the end of the composting experiment. Under A1 treatment, pH was 7~8 and E4/E6 was for most of the time lower than in CK and A2. Polyphenoloxidase and dehydrogenase activities in A1 were the highest. However, dehydrogenase activity occurred concurrently with other processes that resisted enzyme activity.

Temperature and relative humidity during air-curing and their effects on burley tobacco quality in different curing barns

WANG De-Bao, SHI Hong-Zhi, YANG Xing-You, ZHOU Kai-Xu, ZHAO Xiao-Dan, WANG Rui-Yun, JIN Dong-Mei

2011, 19(6): 1405-1411. doi: 10.3724/SP.J.1011.2011.01405

Abstract(1363) PDF(1312)

Abstract:
Five air-curing barns (black plastic-film barn, red tile barn, American barn, mud barn and steel frame barn) were established in Dazhou City, Sichuan Province. Differences in temperature and relative humidity during burley tobacco air-curing among the different barns were then investigated. Tobacco leaf quality after air-curing in different barns was also determined. The results showed significant differences in adjustment of temperature and relative humidity among the different barns. Average temperature in different barns was in the order of: American barn > steel frame barn > red tile barn > black plastic-film barn > mud barn. Average diurnal amplitude in temperature was in the order of: steel frame barn > black plastic-film barn > mud barn > American barn > red tile barn. Adjustment ability of temperature was in the order of: mud barn < black plastic-film barn < steel frame barn < American barn < red tile barn. On the basis of temperature, steel frame and red tile barns exhibited the best effects while black plastic-film and mud barns exhibited the worse effects. Average relative humidity in different barns was in the order of: black plastic-film barn > mud barn > American barn > red tile barn > steel frame barn. Differences in relative humidity between barns and outdoors was in the order of: black plastic-film barn > mud barn >American barn > steel frame barn > red tile barn. On the basis of relative humidity, steel frame and red tile barns showed the best effects while black plastic-film and mud barns showed the worse effects. There was no obvious effect of air-curing in the different barns on the quality of leaf tobacco appearance. The appearance of burley tobacco air-cured in 5 barns met high-quality standard appearance requirement. There were differences in the impacts of different barns on chemical compounds of tobacco. Except for high sugar in mud barn, chemical components of air-cured burley tobacco basically conformed with high-quality burley tobacco requirement. Analysis of construction cost, practicality, heat preservation and dehumidifying effects as well as the effects on chemical compounds showed that steel frame barn was most consistent with local high-quality burley tobacco requirements.

Effect of low temperature on reservoir water and mechanical control measure

ZHANG Shi-Jie, LIU Chang-Ming, TAN Hong-Wu, LI Guo-Qiang

2011, 19(6): 1412-1416. doi: 10.3724/SP.J.1011.2011.01412

Abstract(1321) PDF(2026)

Abstract:
Thermal stratification of reservoirs is a critical ecological factor for regulating direct and indirect effects of temperature on reservoir productivity. In particular, low temperature reservoir waters have adverse effects on agricultural/aquatic ecology. Selective water withdrawal from different reservoir depths is used to manage water demand for different uses. In China, stoplog gate are constructed in large reservoirs to regulate water temperatures for crop irrigation and fish breeding. When water is withdrawn from different reservoir depths, flow patterns, stratification and therefore water quality in the reservoir are altered. Vertical 1-D or 2-D water temperature models were applied to analyze the effects of selective water withdrawal on thermal structure and release water temperature in reservoirs. In this study, thermal stratification and the related seasonal variations in reservoirs were simulated. The effects of two different water withdrawal schemes on water release temperature were analyzed using the MIKE-3 numerical simulation model. Based on the model simulation, stoplog gates effectively improved low temperature water conditions. The predicted thermal stratification and water temperature profiles were noticeably influenced by withdrawal schemes. There were significant differences in the regulation effects of water withdrawal on release temperature between single-layer entry and stoplog gate. From March to September, water temperature was higher by 2~4 oC in stoplog gate than in single-layer entry scheme. The water release temperature of stoplog gate scheme reached 18.4 oC in May, which was the required water temperature for fish spawning. It was therefore concluded that stoplog gate was a more suitable engineered structure. It was not only ecologically friendly, but also effectively improved water temperature, mitigated ecological effects, and ensured coordinated environmental protection and socio-economic efficiency.

Evaluation of exploitation suitability of unutilized arable lands in ecologically fragile areas — A case study of Datong City, Shanxi Province

LEI Shu-Xia, HAO Jin-Min, WANG Li-Min

2011, 19(6): 1417-1423. doi: 10.3724/SP.J.1011.2011.01417

Abstract(2044) PDF(1773)

Abstract:
Datong City is in Northwest China. As a main coal production base, the city is in a relatively fragile ecological environment region. Human activity has greatly affected land ecological environment in this region. This paper used Fuzzy analysis to regionalize ecological fragility of Datong City based on administrative districts. This was important for the evaluation of exploitation suitability of unutilized arable lands in different areas of the city. The indicators for regionalization of ecological fragility were natural factors, such as those involved in terrain, physiognomy, meteorology and hydrology, and artificial factors, such as those involved in land use, society, and economy. The weights of indicators were decided by using AHP method and the ecological fragility was classed into four level, which were micro, slight, moderate and severe levels. The evaluation results showed that Nanjiao District, Yanggao County, Zuoyun County and Tianzhen County were severe ecologically-fragile regions. Hunyuan County was a moderate ecologically-fragile region. Then Guangling County was a mild ecologically-fragile region. Xinrong District, Datong County and Lingqiu County were weak ecologically-fragile regions. On the base of regionalization of ecological fragility of the city, the exploitation suitability of unutilized arable lands was evaluated by using the regulated classification of agricultural lands combined with environmental conditions. The evaluation index system was consisted of factors of site, soil, hydrothermal and ecology with a total of eleven indexes. The weights of indexes were decided according to their importance, and the suitability coefficient was calculated. The results showed that 84.09% (468 692.59 hm²) of unutilized arable lands in the region was suitable for cultivation. About 43.77% (205 165.81 hm²) of the unutilized arable lands was in the weak ecologically-fragile region. Also the areas of unutilized arable lands in the mild, moderate and severe ecologically-fragile regions were 52 392.84 hm² (11.18%), 69 427.45 hm² (14.81%) and 141 706.49 hm² (30.23%), respectively. Unutilized arable lands with high suitability for cultivation in the weak ecologically-fragile region were given exploitation priority. Unutilized arable lands with relative suitability for cultivation in the weak, micro-level fragility were a viable alternative. Unutilized arable lands with high suitability for cultivation in mild and severe ecologically-fragile regions were not considered for exploitation.

Establishment and application of source/sink-based agricultural non-point source pollution model

LI Qiang-Kun, HU Ya-Wei, SUN Juan, LI Huai-En

2011, 19(6): 1424-1430. doi: 10.3724/SP.J.1011.2011.01424

Abstract(1234) PDF(1177)

Abstract:
Improving control standards of point (PSP) and non-point (NSP) source pollutions are recent highlights of water and environmental issues. Agricultural non-point source pollution (AGNSP) problems caused especially by heavy use of chemical fertilizers and pesticides are prominent in this regard. Quantitative research on pollution loads is the basis of control standard, evaluation and management of AGNSP. Using AGNSP and unit-load characteristics, an AGNSP model was developed that uses source/sinks modules determine the complex migration routes of pollutants. The source module was further divided into farmland irrigation drainage and farmland contaminant concentration estimation sub-modules. The sink module was also divided into farmland drainage and pollutant migration/transformation sub-modules. By integrating the modules, a complete AGNSP load model was therefore established. The integrated AGNSP model was tested in the Qingtongxia Irrigation District (QID) in upstream reaches of the Yellow River. The 2008 crop pattern was used in the developed AGNSP model to simulate AGNSP load and output in QID. Based on the simulation results, salinity, total phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in QID were 470 099 t, 98.17 t, 3 593 t, 2 122 t and 426 t, respectively. The application of the established AGNSP model indicated that the model presented preferable simulated results, and was practicable in the similar studies.

Using SWAT to simulate runoff under different land use scenarios in Xiangjiang River Basin

LUO Qiao, WANG Ke-Lin, WANG Qin-Xue

2011, 19(6): 1431-1436. doi: 10.3724/SP.J.1011.2011.01431

Abstract(2085) PDF(2624)

Abstract:
Runoff varies with land use types, which in turn affects eco-sustainable development of river basins. In this study, SWAT (Soil and Water Assessment Tool) was used to simulate monthly runoff in relation to land use in Xiangjiang River Basin (XRB). Observed runoff data were collected from the Xiangtan, Zhuzhou, Hengshan, Hengyang and Guiyang monitoring stations. A total of seven model parameters were calibrated with data for 1998~2002 and validated for 2003~2007. The coefficient of determination of linear regression (R²) of the observed and simulated monthly runoff and the corresponding Nash-Sutcliffe Index (NSI) were used to evaluate the model performance. With the exception of Guiyang station, all R² and NSI values were higher than 0.82, with some as high as 0.92. The results showed that SWAT reliably simulated runoff in XRB. Given the high model performance, three scenarios (based on the 2006~2020 comprehensive land use planning in Hunan Province) were used to study the impact of land use type on runoff in XRB. Compared with the existing land use conditions, predicted runoff dropped by 1.28 mm under scenario 1 (where 165.40 km² of agricultural land was changed into forest land and 793.91 km² of agricultural land changed to grassland). Under scenario 2 (where 8 173.96 km² of forest land was reclaimed for agriculture in the upstream basin and 337.56 km² of agricultural land in downstream basin put under urban developed), predicted runoff rose by 15.61 mm. In scenario 3 (where 500.02 km² of unused arable land was reclaimed for agriculture), predicted runoff increased by 1.16 mm. The scenario simulation suggested that runoff dropped under increasing forest land and grassland areas and decreasing paddy field and urban areas. Hydrological effects, economic benefits and human activities were identified as critical factors of runoff and water resources availability in the basin. It was concluded that these factors should be fully taken into account in land use planning and development in XRB.

Regional differences and reasons for farmers' irrigation as households perspective: A case study of Sangong River Basin

XIAO Yan-Qiu, ZHANG Xin-Huan, YANG De-Gang

2011, 19(6): 1437-1443. doi: 10.3724/SP.J.1011.2011.01437

Abstract(1084) PDF(1151)

Abstract:
Uneven spatial and temporal distribution of water shortage coupled with low water use efficiency is a critical constraint to socio-economic development in semi-(arid) regions. Using questionnaires, quantitative statistics and OLS estimation, this study analyzed the regional differences in irrigation as affected by farmer household characteristics in the Sangong River Basin. The study showed gradual increases in water-saving facilities and water price from the upper reaches down to the lower reaches of the basin. Water-saving irrigation ratios were 3%, 10% and 28% in the upper, middle and lower reaches, respectively. The corresponding water price in the upper, middle and lower reaches was <0.075 Yuan·m^-3, 0.069~0.075 Yuan·m^-3 and 0.13~0.35 Yuan·m^-3, respectively. There was a gradual decline in irrigation amount and water burden from the upper down to the lower reaches. Irrigation amount in the upper, middle and lower reaches was 18 510 m³·hm^-2, 12 810 m³·hm^-2 and 9 075 m³·hm^-2; water burden were 18%, 14% and 12% respectively. In the basin, planting structure had evolved from traditional to cash driven crops with increasingly rational cultivation structures. Natural factors were the most fundamental reasons for differences in irrigation among different regions. The amount of water resources, soil retention capacity, field size and fragmentation influenced not only farmers' awareness of water conservation, but also choices of water-saving facilities. This had led to differences in farmers' irrigation modes, which in turn significantly influenced local governments' decision-makings. While local governments passed irrigation burdens to farmers by increasing water price, they also enhanced water use efficiency and crop-irrigation demand curve by improving canal quality and subsidizing the costs of water-saving facilities. Empirical analysis showed that when water price rose by 0.01 Yuan·m^-3, irrigation amount dropped by 484 m³·hm^-2. By using drip irrigation, irrigation amount dropped by 1 617 m³·hm^-2. Also by improving water canal quality from earth to cement pavement, irrigation amount dropped by 736 m³·hm^-2.

Construction and application of comprehensive benefit evaluation system on low carbon agriculture in North Fujian

LUO Xu-Tian, WU Ze-Yan, CHEN Ting, LIN Wen-Xiong

2011, 19(6): 1444-1447. doi: 10.3724/SP.J.1011.2011.01444

Abstract(1318) PDF(1354)

Abstract:
Low carbon agriculture is a hot issue in modern agricultural research. However, comprehensive evaluation of the benefits of low carbon agriculture is limited. This paper analyzed the significance of constructing comprehensive evaluation system of the benefits of low carbon agriculture. The analytic hierarchy process (AHP), Delphi method and fuzzy comprehensive evaluation method were used to evaluate the benefits of low carbon agriculture with the aim of shifting from qualitative to quantitative evaluation system, using Luxia Town in Nanping City, Fujian Province as a case study. The comprehensive evaluation index system of low carbon agriculture benefit (consisting of 3 first-level and 20 second-level indices) was built based on selected evaluation weight indices as well as on calculated indices. It was then applied to evaluation of low carbon agriculture benefits in Luxia Town. The result showed that low carbon agriculture gained overall benefits in the region. The compressive benefit score was 0.723 9 and the index scores of ecological, social and economic benefits were 0.698 2, 0.592 3 and 0.472 0, respectively. The above results suggested that the index system was suitable for evaluating low carbon agriculture benefits in north Fujian. The study provided a useful base for low carbon agriculture production practice in China.

Evaluation on agricultural production efficiency of Guangdong Province by using DEA window analysis

QIN Zhong, ZHANG Jia-En, LUO Shi-Ming, ZHANG Jin

2011, 19(6): 1448-1454. doi: 10.3724/SP.J.1011.2011.01448

Abstract(1569) PDF(1164)

Abstract:
Agricultural production efficiency is of the basis of comprehensive productive capacity of agriculture. Guangdong Province is now in promotion stage of modern agricultural development, which emphasizes agricultural production efficiency research. Using DEA (data envelopment analysis) theory, agricultural input-output efficiencies in 21 city-regions in Guangdong Province were calculated for 1994~2007. The relative efficiency and dynamic behavior of agricultural production were compared and evaluated laterally (i.e., the same region but at different time windows) and longitudinally (i.e., different regions at the same time window). The results depicted some gaps in average agricultural productivity and dynamic stability among regions. Agricultural input-output performance of the Pearl River Delta was relatively optimal. Although the performance level in the “east-west double wings” region was less than that in the Pearl River Delta region, developmental trend in agricultural productivity in the “east-west double wings” was more stable. Regions of lower agricultural productivity and significant fluctuations were concentrated in the mountain areas of northern Guangdong. While the lowest agricultural productivity efficiency was in Qingyuan City, the highest variation in agricultural productivity was in Shaoguan City. The findings laid not only the basis for in-depth insight into provincial agricultural input-output efficiency and development trends, but also provided information basis for related departments to establish management policies that can enhance agricultural productivity.

Historical review of Agronomy both as a discipline and a specialty and its reframing: Taking Agroecology as its core theoretical subject

WANG Song-Liang

2011, 19(6): 1455-1460. doi: :10.3724/SP.J.1011.2011.01455

Abstract(1436) PDF(1387)

Abstract:
Modern agronomy (initiated by experimental sciences of reductionism thinking and motivated by industrialized European revolution) had led to astronomical increase in agricultural production, but at a huge cost of destroying the natural base of agricultural sustainability. The prevalence of reductionism thinking disassembled agronomy into smaller disciplines in university education system across the globe. This led to the so-called “Therapeutic Intervention” in applied fields of agriculture, which in turn posed current problems in modern agricultural systems. Such problems included soil degradation, loss of agro-biodiversity and food safety due mainly to over-use of synthetic fertilizers and pesticides. Using crop cultivation/farming systems and plant genetics/breeding, the second-grade disciplines of agronomy as examples, the focus of the former was under community scale and that of the latter was under population scale, in terms of ecology. Comparative review showed that most of the problems of modern agriculture occurred beyond ecosystem scale. It was therefore imperative to gradually reframe agronomy and its educational systems with the goal of developing sustainable agricultural production strategies. In this paper, the author proposed bridging agronomy with ecology. This posed agroecology as a core discipline, upon which crop cultivation, cropping system and crop genetics/breeding research was regulated and broadened. These sub-disciplines of agronomy used agro-ecosystem management as a core applied system that integrates modern biological, ecological, information and material engineering. Methodologically, it paved a practical path to sustainable modern agriculture by integrating China's archaic deductivism thinking with western neoteric reductionism thinking.

Framework and guiding principles of index system construction of green agriculture in China

ZHANG Zheng-Bin, WANG Da-Sheng, XU Ping

2011, 19(6): 1461-1467. doi: 10.3724/SP.J.1011.2011.01461

Abstract(1414) PDF(1925)

Abstract:
In this paper, we argued that green agriculture or green food safety law was the basis of agricultural product quality safety law which was in turn the basis of food safety law. Green agriculture was presented as the main stream of modern agricultural development. Green food was then to replace safe/organic foods. With the establishment of green agriculture international alliance, accelerated internationalization of green agriculture and green food was critical for the present and future agricultural development in China. We suggested a sped-up establishment of the framework and guiding principles of China's green agriculture index system construction to lay the theoretical basis for building and assessing green agriculture. The framework and guiding principles of standard systems to establish China's green agriculture was also critical for laying constructive guidelines for the formulation of food safety standards at departmental and professional levels, which would speed up the comprehensive formulation of China's food safety standards.

A review of researches on evolution of soil organic carbon in mollisols farm-land

GAO Chong-Sheng, WANG Jian-Guo

2011, 19(6): 1468-1474. doi: 10.3724/SP.J.1011.2011.01468

Abstract(1758) PDF(1998)

Abstract:
At present, more and more people in China are concerned with mollisols with the need of food safety and agricultural sustainability. The studies concerning Chinese mollisols has become a hot topic. Moreover, soil organic matter (carbon) of Chinese mollisols is the hottest issue for scholars. Therefore, this paper described mollisols distribution, reclamation history, organic carbon evolution and specific contribution to agriculture in China; systematically analyzed study methodologies of farmland soil organic carbon. The significance of researches on evolution and prediction of soil organic carbon for Chinese mollisols was discussed. Finally, future studies on soil organic matter (carbon) in mollisols were suggested. The review showed that future research should be focused on change and management of soil organic carbon in mollisols farmland to establish theory and method of protection and utilization of soil organic carbon, such as fertility control technology, evaluation method and prediction model.

Review of the effect of sprinkler-irrigation with brackish water on crops

SUN Ze-Qiang, DONG Xiao-Xia, WANG Xue-Jun, ZHENG Dong-Feng, LIU Zhao-Hui

2011, 19(6): 1475-1479. doi: 10.3724/SP.J.1011.2011.01475

Abstract(1363) PDF(1372)

Abstract:
A review of sprinkler-irrigation with brackish water effects on crops showed that both soil salt and sprinkler-irrigated brackish water salt affected crop growth and productivity. Salt absorption rate by plant leaf was linear functionally related with water salt concentration and irrigation duration. In order to reduce sprinkler-irrigated water contents of magnesium, chlorine and sodium, it was critical to monitor electrical conductivity and ion composition of source waters. Generally, increasing irrigation frequency led to a greater increase in salt absorption and plant damage than increasing irrigation duration. Sprinkler-irrigation with fresh water following sprinkler-irrigation with brackish water reduced leaf salt uptake. Sprinkler-irrigated brackish water limited not only biomass and cumulative water consumption of mature plants, but also reduced crop yield. However, crop yield was not significantly related with leaf sap ion concentration. It was suggested that future studies focused on five main research tasks. The first was the study of salt tolerance of crops under sprinkler-irrigation of brackish waters with aim of establishing a standard evaluation system. The second was breeding salt-resistant crop varieties to sprinkler-irrigation with brackish waters which could be especially useful in breeding salt-tolerant grass, turf-grass restoration, urban greening and saline soil amendments. The next suggested focus was developing adaptable irrigation schedules for sprinkler-irrigation with brackish water. It was also important to study the leaching of salt from leaves and soils under sprinkler-irrigation with brackish water condition. The next point was analyzing, in time and space, long/short-term impacts of sprinkler-irrigation with brackish water on the crops. The last point was to study the effects of sprinkler-irrigation with brackish water on the accumulation and distribution of soil salts.

Impact of different allelochemicals on protective enzyme system of exotic invasive plant Ipomoea cairica (Linn.) Sweet

SUN Yan-Jie, ZHUANG Dong-Hong, DU Hong, XU Xiao-Hua, MA Rui-Jun

2011, 19(6): 1480-1482. doi: 10.3724/SP.J.1011.2011.01480

Abstract(1412) PDF(1206)

Abstract:

Spraying Youmaguijia, a Si and K preparation, alleviated fertility losses from heat stress in rice

WU Chen-Yang, MA Guo-Hui, FU Yi-Chuan, LUO Hai-Wei, TIAN Xiao-Hai

2011, 19(6): 1483-1485. doi: 10.3724/SP.J.1011.2011.01483

Abstract(1297) PDF(1102)

Abstract:

2011 Vol. 19, No. 6