中国生态农业学报(中英文)

Effect of integrated rice-duck farming on rice canopy structure index

ZHANG Jin, ZHANG Jia-En, QIN Zhong, FU Ling, LIANG Kai-Ming

2012, 20(1): 1-6. doi: 10.3724/SP.J.1011.2012.00001

Abstract(2061) PDF(1603)

Abstract:
Although rice canopy structure is a critical factor that influences rice yield and quality, few research has been conducted on the effects of rice-duck farming on rice canopy structure. In a field experiment therefore, canopy structure characteristics at tillering and full-heading stages of late rice were compared between rice-duck farming and conventional rice farming (control) treatments. The results showed that rice-duck farming increased rice canopy width but decreased basal width. Furthermore, the leaf loose rate of rice-duck farming increased by 12.2% and 42.3% at tillering and full-heading stages, respectively, compared with the control. Rice-duck farming lowered leaf length, opening angel and drooping degree of the fourth and third leaves. The opposite effects were, however, noted for the second and flag leaves. This made the upper leaves flatter and the lower leaves more erect than the control treatment. This in turn enhanced leaf area distributed in upper canopy horizon. Rice-duck farming increased rice basal leaf height. Compared with the control, this resulted in significant differences at full-heading stage. The findings of the study indicated that rice-duck farming had positive effects on rice stem and tiller development in the early and middle growth stages. It improved growth of upper functional leaves which was beneficial to rice yield formation at late growth stage.

Response of denitrifying bacteria community structure and abundance to nitrogen in paddy fields

SONG Ya-Na, LIN Zhi-Min, LIN Yan

2012, 20(1): 7-12. doi: 10.3724/SP.J.1011.2012.00007

Abstract(4086) PDF(3836)

Abstract:
Denitrification is critical for nitrogen cycle in the ecosystem, where fixed nitrogen is released into the atmosphere as N₂. Nitrite reductase, the product of nirS or nirK nitrite reductase genes, is the key enzyme of bacteria dissimilatory denitrification process. Denitrifying bacteria community composition varies with environmental factors such as temperature, moisture, pH, O₂ and nutrient availability. There is obvious denitrification process in flooded paddy fields. Hence denitrifying bacteria community structure and abundance in paddy fields are used to investigate the response of denitrifying bacteria to nitrogen fertilizer application in paddy fields. The experiment was conducted in a second-year nitrogen fertilization field with the aid of denaturing gradient gel electrophoresis and real-time PCR assay copies of nirS gene. DGGE images of nirS gene in root-zone soil and surface soil showed rich abundance of denitrifying bacteria in paddy soils. DGGE band number in surface soil image was higher than that in root-zone soil. Principle components analysis (PCA) of nirS gene DGGE profile showed that denitrifying bacteria community structure in root-zone or surface soil of paddy fields with nitrogen fertilizer [N: 150 kg(N)·hm^-2] was similar to that of paddy fields without fertilizer (CK) during rice growth stages of tillering, heading and maturity. Also no difference was noted in denitrifying bacteria community structure in root-zone soil or surface soil among different growth stages of rice. Denitrifying bacteria nirS gene copy abundance in root-zone or in surface soil with nitrogen fertilizer treatment was significantly (P < 0.05) higher than that of CK treatment during rice growth. In both nitrogen fertilizer and CK treatments, denitrifying bacteria nirS gene copies in root-zone soil markedly (P < 0.05) dropped at maturity stage of rice growth. There were, however, no differences in nirS gene copies in surface soil among the different rice growth stages. At maturity stage, nirS gene copies in surface soils of both nitrogen fertilizer and CK treatments were higher (P < 0.05) than those in root-zone soils. Furthermore, rice yield in nitrogen fertilizer treatment was 44% higher than that of CK. In conclusion, denitrifying bacteria abundance was not only variable but also actively responded to nitrogen fertilizer supply. On the other hand, denitrifying bacteria community structure was not only relatively stable but largely unresponsive to nitrogen fertilizer supply. The study demonstrated that nitrogen fertilizer enhanced denitrifying bacteria abundance, which was critical for nitrogen cycling in paddy field ecosystem.

Effects of soil fertilizer amendment on growth during critical growth stages and yield of winter wheat

ZHOU Li-Feng, FENG Hao

2012, 20(1): 13-18. doi: 10.3724/SP.J.1011.2012.00013

Abstract(1982) PDF(1848)

Abstract:
Reasonable irrigation and fertilization are key factors of winter wheat production. Field experiments were conducted in 2009~2010 with “Xiaoyan 22” as materials. The effects of soil fertilizer amendment (SFA) on water content along soil profile and growth at critical growth stages and yield of winter wheat were investigated. The results show that yield under SFA treatments was 10%~30% higher than that under normal fertilization (NF) treatment. Optimum SFA increased with increasing irrigation amount. Theoretical maximum yield was 8 894.11 kg·hm^-2, which was under single irrigation with 1 350 kg·hm^-2 SFA. At the start of jointing stage, soil water content under SFA treatments initially increased steadily and then slowly decreased in a V-shaped distribution curve from surface to deep layer along soil profile, quite different from the W-shaped distribution curve under NF treatment. At grain-filling stage, the depth of max and min soil moisture content under SFA occurred much deeper than that under NF treatment. At tillering stage, plants under SFA treatments were low with relatively thick and short roots. This trend was more obvious at higher fertilizer application rates. At grain-filling stage, however, plant height was lowest, spike dry-matter and dry-weight of aboveground part were highest under middle SAF treatment. In the middle of SFA treatment, wheat filling rate was significantly higher than that under all other treatments. Thus SFA deepened the position of max and min soil moisture content along soil profile. Wheat growth rate under SFA was higher than under NF treatment. SFA treatment facilitated optimal production in low water conditions (jointing stage irrigation of 60 mm) than NF treatment.

Effects of NBPT urease inhibitor on ammonia volatilization in paddy fields with wheat straw application

PENG Yu-Jing, TIAN Yu-Hua, YIN Bin

2012, 20(1): 19-23. doi: 10.3724/SP.J.1011.2012.00019

Abstract(2210) PDF(2615)

Abstract:
While ammonia volatilization is the main mode of nitrogen loss in paddy fields, urease inhibitors are known to effectively inhibit urease activity, delay urea hydrolysis and reduce ammonia emission. Urease inhibitors have, however, not been widely applied in paddy fields. In this study, the effects of NBPT urease inhibitor on the dynamic changes in urea hydrolysis and ammonia volatilization in wheat-straw incorporated gley paddy soils in Taihu Lake region were investigated via the dynamic chamber method. Results showed that ammonia volatilization mainly occurred during basal and tillering fertilization periods. While the highest ammonia volatilization was at basal fertilization stage, the lowest was at booting fertilization stage. Ammonia volatilization mainly occurred within three days after fertilization. Applying NBPT one day before fertilization significantly retarded urea hydrolysis, delayed occurring time and decreased value of NH₄⁺-N peak and reduced rate and amount of ammonia volatilization of surface water. After basal and tillering fertilization, urea hydrolysis ended within 2~3 days after fertilization, NH₄⁺-N and ammonia volatilization peaks occurred on the second day under non-NBPT treatment. Peak values of NH₄⁺-N of basal and tillering fertilization were 132.3 mg·L^-1and 66.3 mg·L^-1, respectively. Also ammonia volatilization peak values were 15.6 kg·hm^-2·d^-1 and 10.4 kg·hm^-2·d^-1, respectively. Under NBPT treatment, however, the peak of NH₄⁺-N occurred 4 days after fertilization after which it dropped to 70.7 mg·L^-1 and then to 51.6 mg·L^-1. After 4 days of fertilization, ammonia volatilization peak dropped to 4.7 kg·hm^-2·d^-1 and then to 2.6 kg·hm^-2·d^-1. Total ammonia volatilization dropped from 73.3 kg(N)·hm^-2 (24.4% of applied N) to 34.5 kg(N)·hm^-2 (11.5% of applied N) after NBPT application, a drop of 53%. NBPT application in wheat-straw incorporated paddy fields significantly reduced ammonia volatilization by delaying urea hydrolysis. It was recommended that NBPT urease inhibitor could be used as nitrogen fertilizer additive to inhibit ammonia loss in paddy fields.

Nitrogen-15 labeling and nitrogen transformation in silage maize-cattle manure system

YUE Xian-Lu, LIAO Shang-Qiang, JI Hong-Jie, ZHANG Wei-Li, ZUO Yu-Bao, RONG Xiang-Nong

2012, 20(1): 24-27. doi: 10.3724/SP.J.1011.2012.00024

Abstract(1758) PDF(1598)

Abstract:
¹⁵N tracer technique has been used in N cycling and utilization for livestock manure. The abundance and amount of ¹⁵N in different manure components and N forms affect whether ¹⁵N fate is consistent with all manure N. The purpose of this article is to better understand the characteristics of ¹⁵N transformation in silage maize-cattle manure system and distribution in cattle feces and urine by using ¹⁵N tracer technique. First, a sand culturing experiment was conducted by watering improved Hoagland nutrient solution with ¹⁵N labeled ammonium sulfate (AS, 60 atom% ¹⁵N) to cultivate ¹⁵N labeled maize (“Nongda-108”). Then, ¹⁵N labeled maize was mixed with unlabeled maize at a ratio of 55︰45, according to their amount of nitrogen, to get mixed ¹⁵N forage. Finally, a 2-years-old cattle starved for 2 days was fed on the mixed ¹⁵N forage for 4 days and starved 2 days again. During the 6 days, cattle feces and urine were collected and measured separately. The results showed that ¹⁵N abundance was 48.024% in labeled maize, 26.579% in mixed silages, and 8.044% in cattle manure. In addition, 26.3% of AS ¹⁵N was discovered in maize, 36.0% of silage ¹⁵N was discovered in cattle manure. In all the manure N collected, fecal N, urine N, fecal ammonium N and urine ammonium N accounted for 70.25%, 29.75%, 5.44% and 0.03%, their ¹⁵N abundance were 9.223%, 5.261%, 6.505% and 5.419%, respectively. In ¹⁵N labeled manure of cattle fed on ¹⁵N labeled silage in a short period, the abundance of ¹⁵N in cattle urine and feces, and in different N forms were different. The ¹⁵N abundance of urine was lower than that of feces, and ¹⁵N abundance of mineral and easy-mineralized nitrogen was lower than that of hardly mineralized nitrogen.

Effect of nitrate inhibitors on endogenous nitrate metabolism in Chinese cab-bage

HUANG Dong-Feng, LI Wei-Hua, QIU Xiao-Xuan, WANG Li-Min

2012, 20(1): 28-33. doi: 10.3724/SP.J.1011.2012.00028

Abstract(1622) PDF(1390)

Abstract:
Soil-pot experiment consisting of a control treatment (with nitrate-N∶ammonium-N = 2∶3 denoted as S1) and 3 trial treatments (with application of dicyandiamide, imidazole and pyridine nitration inhibitors on the base of S1 and respectively denoted as S2, S3 and S4) were conducted to study the effects of nitrate inhibitors on endogenous nitrate metabolism in Chinese cabbage. Results showed that the 3 nitrate inhibitors increased vegetable cabbage yield by 6.06%~28.55%, N absorption by 2.38%~38.42% compared with S1. S2, S3 and S4 treatments decreased plant nitrate concentration by 2.69%~19.66% and increased leaf NRA (nitrate reductase activity), MPS (metabolic pool size), SPS (storage pool size) and MPS/SPS by 24.28%~77.32%, 29.45%~272.17%, 2.78%~17.38% and 0.04%~0.59%, respectively. This subsequently enhanced the availability of endogenous nitrate in Chinese cabbage. Treatment S2 had the highest improvement in yield, N absorption and availability of endogenous nitrate in Chinese cabbage. Treatment S2 yield and absorption amounts of N were 56.72 g·pot^-1 and 0.156 g·pot^-1, respectively. However, plant nitrate content in S2 (1 749 mg·kg^-1) was relatively low. Leaf NRA and MPS in S2 were 1.90 μg(NO₂^--N)·30 min^-1·g^-1(FW) and 0.33 μg(NO₂^--N)·g^-1(FW), respectively.

Effects of grafting on potassium use efficiency of different cotton genotypes

XIA Ying, JIANG Cun-Cang, WANG Xiao-Li, HAO Yan-Shu, CHEN Fang, LU Jian-Wei

2012, 20(1): 34-39. doi: 10.3724/SP.J.1011.2012.00034

Abstract(1637) PDF(1332)

Abstract:
Although cotton (Gossypium hirsutum L.) is generally much more sensitive to potassium use deficiency (KUE) than most other crops, potassium (K) requirements of different cotton cultivars vary greatly. They are therefore critical both to identify high KUE cotton genotypes, and determine the differences in the mechanisms of K use among different cotton genotypes. In recent decades, the use of grafting to enhance cotton resistance to soil diseases has been extended to increase nutrient use efficiency (NUE). To that end, two cotton genotypes (a high KUE and yield potential 103 and a low KUE and yield potential 122 genotypes) were carefully screened from 86 cotton cultivars in the Plant Nutrition Laboratory of Huazhong Agricultural University during 2001—2005. Then a pot experiment was conducted to determine the differences between the screened genotypes in terms of KUE, yield, assimilation partitioning, root/shoot ratio, harvest index and K content/partition. Both the ungrafted (103 and 122) and self-grafted (103/103 and 122/122) cotton genotypes were investigated under different K [applied 0.55 g(K₂O)·kg^-1(soil) and 0 g(K₂O)·kg^-1(soil)] treatments. The results showed that grafting had different degrees of effect on dry-matter and K accumulation/distribution and yield of the two cotton genotypes under different K conditions. Dry-matter and accumulated K contents of vegetative organs were higher in 103/103 than in 103. Conversely, dry-matter and accumulated K contents of reproductive organs were lower in 103/103 than in 103. Furthermore, 103/103 yield and K use index declined relative to 103. Interestingly, all the conditions of the low KUE cotton genotype 122 completely changed after grafting. That was to say that dry-matter and accumulated K contents of vegetative organs were lower in 122/122 than in 122. However, dry-matter and accumulated K contents of reproductive organs were higher in 122/122 than in 122. K uptake efficiency varied with K application level. While K uptake efficiency was lower in 103/103 than in 103 under applied K treatment, the reverse was true under 0 g(K₂O)·kg^-1(soil) treatment. On the contrary, K uptake efficiency was higher in 122/122 than in 122 under 0.55 g(K₂O)·kg^-1(soil) treatment while the reverse was true under 0 g(K₂O)·kg^-1(soil) treatment. It suggested that grafting differently influenced different cotton genotypes, with a more balanced dry-matter distribution in grafted cotton genotypes. The results laid the theoretical basis for further insight into K uptake and use efficiency by different cotton genotypes.

Effects of combined high temperature and drought stress on amylose and protein contents at rice grain-filling stage

GAO Huan-Ye, WANG San-Gen, ZONG Xue-Feng, TENG Zhong-Hua, ZHAO Fang-Ming, LIU Zhao

2012, 20(1): 40-47. doi: 10.3724/SP.J.1011.2012.00040

Abstract(2472) PDF(1428)

Abstract:
Grain-filling stage is a critical stage for rice yield and quality. There have been frequent high temperatures and droughts in several rice production regions in South China due mainly to global climate change but also to local topographic conditions. This has resulted in simultaneous decline in rice yield and quality. This study investigated the combined effects of high temperature and drought stress on rice quality at grain-filling stage via analyzing the changes in amylose and protein contents of indica rice (introgression line of H5 with induced genes of Alternanthera hiloxeroides). A pot experiment was conducted in greenhouse conditions with experimental treatments including optimal temperature plus moderate drought (OT-MD), optimal temperature plus severe drought (OT-SD), high temperature plus well-watered condition (HT-WW), high temperature plus moderate drought (HT-MD), high temperature plus severe drought (HT-SD) and then optimal temperature plus well-watered condition (OT-WW) as the control treatment (CK). In addition to CK, treatment durations were set at 10 days, 20 days, 30 days and 40 days, respectively. The results showed that while amylose content decreased, that of protein increased during high temperature period. Compared with CK, amylose content dropped by 1.783%~5.987% while that of protein increased by 1.178%~2.741% during 10~40 days heat period. A similar trend was noted for drought conditions. In other words, amylose content decreased while protein content increased during drought. Compared with CK, amylose content decreased by 1.956%~6.270% while protein content increased by 1.153%~2.944% under 10~40 days of OT-MD treatment. Stress-driven changes in amylose and protein contents were higher under OT-SD treatment than under OT-MD treatment. While combined drought and high temperature stress reduced amylose content, it enhanced protein content. The ranges for amylose and protein contents of rice due to combined high temperature and drought stress were higher than that due to the individual high temperature or drought stress. The degree of changes in amylose and protein contents increased with increasing intensity, duration and frequency of the stress. Rice quality deterioration at the 20th days of grain-filling was mainly caused by the effect of combined high temperature and drought stress. An ascending order of the stress effect arrangement on amylose and protein contents under the same treatment periods was as follows: HT-WW < OT-MD < OT-SD < HT-MD < HT-SD. This study laid the basis for drought and heat resistance of rice, a critical element in rice breeding and cultivation.

Distributions of endogenous hormones relative to formation of cracked and malformed fleshy roots of carrots

YANG Yong-Gang, ZHANG Hua-Sheng, LI Ya-Li, QU Ya-Ying

2012, 20(1): 48-52. doi: 10.3724/SP.J.1011.2012.00048

Abstract(1306) PDF(1229)

Abstract:
Endogenous hormones (an important internal factor) promote fleshy root thickening in carrot by controlling root sink activity, however, it is not entirely clear whether the distribution of endogenous hormones is related with the formation of cracks and deformities in fleshy root of carrots. The distributions of endogenous hormones across transverse section and along longitudinal section of normal, cracked and deformed fleshy root of carrot (“Qishantouxinhong”) were investigated using the ELISA method. The relationship between the endogenous hormones contents and formation of cracked and malformed flesh roots of carrots was discussed. The results showed that GA₃, GA₄, ZR, DHZR and IAA contents in the outer and mid-outer transverse sections of cracked fleshy roots of carrots were lower than those in the other parts of the plant during the fast metaphase stage of root thickening. Also the contents of GA₃, GA₄, ABA and IAA in outer and mid-outer transverse sections of cracked fleshy root of carrots were lower than those in the other parts of the plant during the fast telophase stage of root thickening. Compared with outer-dominance in normal fleshy roots, endogenous hormone distribution was dominant in the inner and middle vertical cross-sections of cracked fleshy root carrots. This could have led to the formation of cracks in fleshy root carrots. Also compared with top/end-dominance in normal fleshy root carrots, the distributions of GA₄, ZR and DHZR contents exhibited an end-dominance along the longitudinal cross-sections of cracked fleshy root of carrots. In fact, GA₃, ABA and IAA exhibited even distributions in malformed fleshy root of carrots during the fast root thickening stage. The analyses showed that variations in the distributions of endogenous hormones resulted in deformities fleshy root of carrots.

Effects of arbuscular mycorrhizal fungi on fusarium wilt and disease resistance-related enzyme activity in cucumber seedling root

WANG Chang-Xian, LI Xiao-Lin, SONG Fu-Qiang, WANG Gui-Qiang, LI Bei-Qi

2012, 20(1): 53-57. doi: 10.3724/SP.J.1011.2012.00053

Abstract(2224) PDF(1495)

Abstract:
Fusarium.oxysporum f. sp. cucumerinum wilt disease severely limits cucumber production. There is a symbiotic relationship between arbuscular mycorrhizal fungus and over 80% of vascular plants including cucumber. This relationship is not only beneficial to growth, but also to tolerance of plant to pathogens. A pot experiment was conducted to investigate the bio-control effects of Glomus versiforme and Glomus intraradices against cucumber wilt. Meanwhile, the activities of three disease resistance enzymes in the root were examined. The results showed that the arbuscular mycorrhizal fungi improved cucumber seedling growth and reduced disease severity. G. versiforme presented more obviously growth-promoting and bio-controlling effects than G. intraradices. Compared with the control, G. versiforme significantly enhanced cucumber growth parameters such as seedling height, stem diameter, leaf area and dry weight while reducing disease index by 26.6%. Improved growth and early induction of defense enzymes of mycorrhizal seedlings increased plant disease resistance. Before F. oxysporum f. sp. cucumerinum infection, the main growth parameters (e.g., height, leaf area and dry weight) of G. versiforme or G. intraradices inoculated seedlings were significantly higher than those of the control. The index of seedling quality of G. versiforme inoculated seedlings was respectively 1.19 and 1.22 times of that of G. intraradices inoculated seedlings and the control seedlings. This implied that before F. oxysporum f. sp. Cucumerinum infection, G. versiforme inoculated seedlings were significantly stronger than both the G. intraradices inoculated seedlings and the control seedlings. The highest activities of chitinase, β-1,3-glucanase and PAL in G. versiforme pre-inoculated roots occurred 2, 7 and 7 days earlier than those in the control. The corresponding enzymes activities were 1.44, 2.16 and 92.00 times that of the control, respectively. The results provided efficient ways of protecting cucumber seedlings against Fusarium wilt by inducing arbuscular mycorrhizal fungi in cucumber seedlings.

Using micronuclei test and single cell gel electrophoresis assay to evaluate genotoxicity of pesticides to Pardosa astrigera L. Koch

LI Rui, LI Sheng-Cai, LIU Jia, YANG Huai-Qing

2012, 20(1): 58-62. doi: 10.3724/SP.J.1011.2012.00058

Abstract(1366) PDF(1441)

Abstract:
This study combined micronucleus test (MN) and single cell gel electrophoresis technique to assess the genotoxicity of imidacloprid and avermectins to Pardosa astrigera Koch. The micronucleus assay is already widely used in genetictoxicity evaluation due to its clear endpoint, high reproducibility and easy accessibility. The single cell gel electrophoresis technique (comet assay) is a simple, sensitive, reliable, and rapid method to detect DNA damage in eukaryotic cells. P. astrigera, one of the main natural enemies of destructive insects for cropland, orchard, vegetable fields and forest ecosystems, widely distributed in most areas of South and North China. The objective of the study was to achieve a more comprehensive understanding of the effects and potential risks on the spiders of imidacloprid and avermectins, which are normal pesticides, used in the agricultural and forest ecosystems. The results showed significant differences ((P < 0.05, or (P < 0.01) in micronuclei frequency of P. astrigera hemocytes between imidacloprid and avermectins treatments and the control. The micronuclei frequency increased with concentrations of the two pesticides, showing evident dose-effect relationship. The correlation coefficients of imidacloprid and avermectins concentrations with micronuclei frequency of hemocytes were 0.672 8 and 0.989 9 for cephalothorax, 0.800 6 and 0.985 8 for abdomen of P. astrigera respectively. The comet assay showed that DNA damage percentage of pesticide-treated P. astrigera was significantly different from that of the control ((P < 0.01). DNA damage scores expressed as arbitrary units (AU) increased with two pesticides concentrations showing dose-effect relationships. The correlation coefficients of DNA damage in cephalothorax and abdomen hemocytes of P. astrigera with imidacloprid concentration were 0.948 2 and 0.970 4 respectively, and with avermectins were 0.978 1 and 0.975 6, respectively. The frequencies of micronuclei and DNA damage of the abdomen hemocytes of P. astrigera was more serious than those of cephalothorax. MN test and single cell gel electrophoresis assay in this study provided valuable information for evaluation of the pesticides risks to natural enemies and agricultural ecosystems.

Tree structure and 3-D distribution of radiation in canopy of apple trees with different canopy structures in China

GAO Zhao-Quan, ZHAO Chen-Xia, CHENG Jian-Jun, ZHANG Xian-Chuan

2012, 20(1): 63-68. doi: 10.3724/SP.J.1011.2012.00063

Abstract(2032) PDF(1897)

Abstract:
Tree structure and radiation distribution are critical factors influencing photosynthetic productivity of fruit trees as well as fruit yield and quality. The aim of this study was to determine the parameters of tree structure, leaf area density (LAD) 3-D distribution of photosynthetically active radiation (PAR) within four canopy structures (small-sparse canopy, stratified-disperse canopy, spindle canopy and open-center canopy) of apple tree. The experiment was conducted in ‘Fuji’ apple (Malus domestica Borkh. cv. ‘Fuji’) orchard during 2005~2008 growth seasons. The structure parameters of trees with different canopy structures were determined via direct measurement, and PAR of each apple tree canopy measured by quantum sensors. The results showed that the lowest total shoot number (894×10³·hm^-2) and leaf area index (LAI, 2.53) were in open-center canopy. Total shoot and LAI were 2 280×10³·hm^-2 and 4.14, 2 119×10³·hm^-2 and 3.98, 2 190×10³·hm^-2 and 3.88 in small-sparse, stratified-disperse and spindle canopies, respectively. 3-D distribu-tion of LAD was different among the four canopy structures. LAD vertical distribution yielded a distribution mode with height range of 0~4.0 m, largely occurring within 1.0~3.0 m high. While the highest LAD was within 0.5~2.0 m height range in stratified-disperse and spindle canopy structures, it was 0.5~1.5 m and 1.0~2.0 m in small-sparse and open-center canopy structures, respectively. In all the canopy structures, relative PAR decreased with increasing canopy depth. Rapid relative PAR depression was concentrated in middle canopies where LAD was highest. Relative PAR 3-D distribution pattern in unit cells apparently tracked leaf area distribution. The highest average relative PAR and most uniform distribution were in open-center canopy structure. Percent average relative PAR of leaves were 24.85%, 28.84%, 27.71% and 37.28% for small-sparse, stratified-disperse, spindle and open-center canopy structures, respectively. While only 35% leaf area was in the low-light region of open-center canopy structure, over 50% was in the low-light region in the other canopy structures. The main aim of tree pruning was to remove useless shoots and leaves, which were easily identified in 3-D plots. Percent leaf areas in different relative PAR ranges reasonably predicted canopy radiation, which was critical in fruit studies. Leaf and PAR distributions were more uniform in open-center than in other canopy structures. This was a distinct advantage of open-centre canopy structure over the other canopy structures.

Toxicological effect of Agave sisalana Perrine extract on golden apple snail (Pomacea canaliculata Lamarck)

LI Lin-Feng, XU Wu-Bing, ZHONG Qiu-Hua, ZHANG Jia-En, LUO Ming-Zhu, ZHAO Ben-Liang, QIN Zhong

2012, 20(1): 69-74. doi: DOI:10.3724/SP.J.1011.year_id].069

Abstract(1922) PDF(1609)

Abstract:
Pomacea canaliculata Lamarck is an invasive alien species that is very harmful to the ecosystem and rice production in South China. To verify the toxicity and related mechanism of Agave sisalana Perrine to golden apple snail, the toxic effects of aqueous, n-butanol and ethanol extracts of A. sisalana were tested via the snail-immersed method. The effects of n-butanol (59 mg·L^-1, 96 mg·L^-1) and ethanol (180 mg·L^-1, 325 mg·L^-1) extracts on cholinesterase (ChE), superoxide dismutase (SOD) and adenosine triphosphatase (ATPase) activities in hepatic tissue of golden apple snails were also investigated. Based on the results, aqueous, n-butanol and ethanol extracts of A. sisalana had toxic effects on golden apple snail. Their semi-lethal concentrations (LC₅₀) on golden apple snail for 72 h toxicity exposure were 35.3 g·L^-1, 93.3 mg·L^-1 and 298.6 mg·L^-1, respectively. The corresponding 95% confidence interval ranges were 32.9~37.7 g·L^-1, 87.6~99.7 mg·L^-1 and 272.9~318.7 mg·L^-1, respectively. When treated with n-butanol and ethanol extracts for 12 h, SOD activity in snail hepatic tissues showed no obvious change at low concentrations. SOD activity, however, increased significantly at high concentrations. After treatment for 48 h, SOD activity at high concentrations of n-butanol extract was significantly higher than that of the control. However, SOD activity did not show any obvious change in both low and high concentrations of ethanol extract. All A. sisalana extracts somehow increased ChE activity, with n-butanol extract exhibiting higher effect on ChE activity. When treated with 96 mg·L^-1 n-butanol extract for 48 h, ChE activity significantly exceeded that of the control (P < 0.05). Overall, n-butanol extract treatment enhanced ATPase activity at low concentrations and suppressed it at high concentrations. Irrespectively, no obvious pattern change was noted under ethanol extract treatment. In conclusion, A. sisalana was somehow toxic to golden apple snail. A better mode of application was needed for future exploitations.

Relationship between allelopathic potential and grain yield of different allelopathic rice accessions

WANG Hai-Bin, YU Zhen-Ming, HE Hai-Bin, GUO Xu-Kui, HUANG Jin-Wen, ZHOU Yang, XU Zhi-Bin, LIN Wen-Xiong

2012, 20(1): 75-79. doi: 10.3724/SP.J.1011.2012.00075

Abstract(1620) PDF(1520)

Abstract:
Using rice allelopathy to control weeds in paddy fields is a sustainable bio-engineering technique of the 21st century. The main objective of the study was to analyze the relationship between rice allelopathic potential and its grain yield. To that end, 5 different allelopathic rice accessions (allelopathic rice of “PI-1”, “Taichung Native 1”, “Azucena”, “IAC47”; non-allelopathic rice “Lemont”) were analyzed for companion weed biomass and rice grain yield under field conditions in 2008~2010. The results indicated that weed biomass was the highest under non-allelopathic rice “Lemont” and the lowest under allelopathic rice “PI-1”. Furthermore, allelopathic rice “PI-1” had the highest and non-allelopathic “Lemont” had the lowest inhibitory effect on weed. Hence allelopathic rice “PI-1” had the highest grain yield and the reverse was true in “Lemont” under non weeding treatment. Allelopathic rice “PI-1” also had the highest while “IAC47” had the lowest grain yield under weeding treatment. The correlation analysis on weed biomass, rice allelopathic potential and rice yield indicated that grain yields of different allelopathic rice accessions were significantly negatively correlated with weed biomass while significantly positively correlated with allelopathic potential. The results suggested that allelopathic rice “PI-1” had the highest inhibition effect on paddy field weeds, the reverse was true in the case of non-allelopathic “Lemont” in the comparison of 5 different allelopathic rice accessions. Without weeding treatment, “PI-1” grain yield also exceeded those of the other rice accessions. Thus rice accession “PI-1” was the strongest allelopathic accession with the highest grain yield among the 5 rice accessions, the reverse was true in the case of “Lemont”.

Contents of nutrient elements and pollutants in different sources of animal manures

SHAN Ying-Jie, ZHANG Ming-Kui

2012, 20(1): 80-86. doi: 10.3724/SP.J.1011.2012.00080

Abstract(2843) PDF(2522)

Abstract:
Intensive confined livestock and poultry production systems generate large quantities of by-product that can be potentially recycled on lands as manure. Environmental protection is a major consideration for developing management practices that effectively use livestock manure as nutrient resource and soil conditioner in agricultural production. To date, most environmental problems associated with land applications of by-product manure have centered mainly on groundwater and/or surface water contamination by nitrogen and phosphorus nutrients. With increasing use of trace elements such as Cu in nutritional supplements and antibiotics in livestock medicines as feed additives in intensive livestock industries, manure application has become the main source of heavy metal (e.g., Cu, Zn and As) and antibiotic load in soils. By-product manure is applied in farmlands to supply primarily soil N and/or P, without regard to heavy metal pollution. The danger lies in accumulation of manure-borne metals and antibiotics, which threaten food safety and security. To reduce the risk of offsite contamination, it is important to characterize the contents of nutrient elements and pollutants in animal manure. In this study, 155 samples of animal manure (including 93 samples of pig manure, 31 samples of chicken manure, 18 samples of duck manure and 13 samples of cow manure) were collected from both intensive animal farms and household animal houses in different regions of Zhejiang Province. Chemical and spectrum analysis were used to characterize the contents of nutrient elements, heavy metals and antibiotic residues. The results showed low contents of Cd, Cr, Hg, Ni and Pb and high contents of Cu and Zn in animal manure. The ranges of manure contents of Cu, Zn and As were 18.56~1 788.04 mg·kg^-1, 12.46~10 056.68 mg·kg^-1 and 0.69~76.43 mg·kg^-1, with mean values of 525.38 mg·kg^-1, 897.14 mg·kg^-1 and 10.01 mg·kg^-1, respectively. Based on the national standards of heavy metal load limit of sludge for land application (GB4284—84), percent samples of animal manure with Cu, Zn and As exceeding the standard limit were 53.55%, 43.87% and 0.65%, respectively. Residual levels of tetracycline (TC), oxytetmcyline (OTC) and chloroteracycline (CTC) in the manure varied from zero to 16.75 mg·kg^-1, 29.60 mg·kg^-1 and 11.63 mg·kg^-1, with mean values of 2.01 mg·kg^-1, 5.10 mg·kg^-1 and 2.17 mg·kg^-1, respectively. Percent samples of manure with TC, OTC and CTC were 61.29%, 72.90% and 69.03%, respectively. The ranges of N, P and K in the manure were 9.80~43.60 g·kg^-1, 7.98~54.30 g·kg^-1 and 8.76~35.20 g·kg^-1, with mean values of 23.63 g·kg^-1, 24.81 g·kg^-1 and 20.72 g·kg^-1, respectively. Manure P to N ratio range was 0.40~2.98, with a mean of 1.08. P, K, Cu, Zn and As contents as well as those of selected antibiotic residues were generally higher in on-farm animal manure than in household animal manure. These variables were also higher in pig manure than in the manure from other animals. Given the high Cu, Zn and antibiotic amounts of on-farm animal manure, its farm application should be controlled by adopting pretreatment measures that reduces residual antbiotic, Cu and Zn loads.

Quantitative analysis of factors influencing soil Pb content in the high eco-nomic development region of South Jiangsu Province: a case study in Kun-shan City

WAN Hong-You, ZHOU Sheng-Lu, CHEN Jie, ZHAO Qi-Guo

2012, 20(1): 87-92. doi: 10.3724/SP.J.1011.2012.00087

Abstract(1635) PDF(1671)

Abstract:
One hundred and twenty-six soil samples were collected from paddy field, traditional vegetable and protected vegetable fields in Kunshan City, a typical area of the high economic development region of South Jiangsu Province. Multi-statistics regression analysis was used to quantify the factors influencing soil Pb forms in the studied area. The results showed 1.04~12.04 mg·kg^-1 of soil available Pb, with an average value of 3.75 mg·kg^-1. While the average content of soil total Pb was 27.42 mg·kg^-1, the available rate of soil Pb was 15.64%. The order of contents of different forms of soil Pb was as follows: soil residue Pb (15.35 mg·kg^-1) > soil organic-matter bonded Pb (6.68 mg·kg^-1) > soil iron/manganese-oxide bonded Pb (4.27 mg·kg^-1) > soil carbonate bonded Pb (0.76 mg·kg^-1) > soil exchangeable Pb (0.36 mg·kg^-1). Soil residue Pb content was significantly higher (49.79%) than the contents of the other forms of soil Pb. pH was the most important factor affecting soil exchangeable Pb and iron/manganese-oxide bonded Pb contents, it was significantly negatively correlated with contents of the two forms of soil Pb. Soil total Pb content was the most important factor for soil carbonate bonded Pb and residue Pb contents, both of which had significant positive correlation. Soil organic-matter content was the most important for soil organic-matter bonded Pb content, and both had significant positive correlation. pH was also an important factor for soil organic-matter bonded Pb content.

Effects of mushroom cultivation on nutritional value and dynamics of goat ruminal degradability of cottonseed hull

PAN Jun, CAO Yu-Feng, LU Chao, GAO Teng-Yun, WANG Xiao-Xiao, SUN Kai-Jia, ZHANG Li

2012, 20(1): 93-98. doi: 10.3724/SP.J.1011.2012.00093

Abstract(1741) PDF(1255)

Abstract:
Spent mushroom substrate (SMS) is a byproducts of mushroom cultivation, which uses straw and cottonseed hulls as substrate. SMS is an important middle part connecting plants and animals in the entire ecosystem. Cottonseed hulls were fermented during edible fungi cultivation and was one of raw materials of SMS, which can be used as ruminants feed. Six ruminally cannulated local white wether goats (10 month old with 35.42±3.96 kg initial body weight) were used to evaluate the nutritional value and in situ dry mater (DM), organic matter (OM), crude protein (CP), acid detergent fiber (ADF) and neutral detergent fiber (NDF) degradation characteristics of SMS of Pleurotus ostreatus, Auricularia polytricha, Flammulina velutipes and P. ferulae and cottonseed hulls. The study analyzed the effects of mushroom cultivation on nutritional value and dynamics of rumen degradability of cottonseed hull and four SMS. Compared with cottonseed hull, the results showed that DM and OM of the 4 SMSs dropped by 13.09%~19.67% (P < 0.01) and 14.13%~39.52% (P < 0.01), respectively. CP of the 4 SMSs increased by 40.20%~ 34.29% (P < 0.01), while NDF and ADF declined by 3.07%~39.72% (P < 0.01) and 17.80%~45.91% (P < 0.01), respectively. Effective rumen degradability of DM and OM, and a+b value of A. polytricha, F. velutipes and P. ferulae SMSs were significantly (P < 0.01) higher than those of cottonseed hull. Also effective rumen degradability of DM and OM, and a+b value of P. ostreatus SMSs were higher (P < 0.05) than those of cottonseed hull. Then effective rumen degradability of CP and a+b value of P. ostreatus, F. velutipes and P. ferulae SMSs were significantly (P < 0.01) higher than those of cottonseed hull. Effective rumen degradability of NDF and ADF of 4 SMSs increased by 76.72%~702.63% (P < 0.01) and 137.41%~575.31% (P < 0.01), respectively. In conclusion, nutritional value and effective rumen degradability of the 4 SMSs improved by mushroom cultivation on cottonseed hulls, which were also fit for use as feed for ruminants.

Soil seed bank characteristics of different vegetations in typically affected regions of Wenchuan Earthquake — A case study in Subaohe and Weijiagou Basins

LIN Yong-Ming, WU Cheng-Zhen, HONG Wei, YOU Wei-Bin, CHEN Can, LI Jian, LIN Shan

2012, 20(1): 99-104. doi: 10.3724/SP.J.1011.2012.00099

Abstract(1469) PDF(1794)

Abstract:
Geo-hazards induced by the Wenchuan Earthquake destroyed large areas of vegetation in the earthquake affected regions. In particular, surface soil of vegetation was destructed which completely changed soil seed bank in regions with severe damage. Field surveys backed with laboratory experiments were conducted in Subaohe and Weijiagou Basins to study the characteristics of soil seed bank (including species composition, density and diversity), and the relationship between soil seed bank richness and disaster degree. The typical Wenchuan Earthquake affected area with 4 vegetation types (undamaged forest, damaged forest, restored grassland and bare-land) was selected for the study. The results showed that soil seed bank density was 212.5~1 758.3 seed·m^-2 with species number of 4.3~14.7 per 200 m², respectively. Most of the soil seed bank for the 4 vegetation types comprised of perennial herb and annual herbs. The mean species number for soil seed bank and aboveground vegetation were not correlated, except for damaged forests and recovered grasslands. Sorensen index of species composition between soil seed banks and aboveground vegetations were high (> 0.25) in the 2 basins, except for bare-land. It was recommended, based on the above results, to use engineering measures and artificial propagation to improve vegetation survival rate and restoration in regions with severe earthquake destruction.

Anti-soil erodibility of different land use types in Northwest Guangxi Karst Regions

CHEN Jia, CHEN Hong-Song, FENG Teng, WANG Ke-Lin, ZHANG Wei

2012, 20(1): 105-110. doi: 10.3724/SP.J.1011.2012.00105

Abstract(1984) PDF(1533)

Abstract:
Anti-soil erosion index is critical for analyzing soil erosion. In this paper, 7 indices (including soil organic matter, water stable aggregate, structural damage rate, re-aggregation situation/degree, dispersion rate and <0.05 mm silt/clay content) were selected to analyze anti-soil erosion degrees of 5 different land use types via both ANOVA and principal component methods in Northwest Guangxi karst regions. The results showed that soil organic matter contents in original and secondary forestlands were significantly higher (P < 0.05) than those in fallow lands, slope farmlands and artificial forestlands. Fallow lands had higher but insignificant soil organic matter content than slope farmlands and artificial forestlands. Amounts of soil >0.25 mm water stable aggregates and re-aggregation situation/degree in original forestlands, secondary forestlands and fallow lands were significantly higher than those in slope farmlands and artificial forestlands. However, slope farmlands had significantly higher structural damage rate and dispersion rate than other land use types. Structural damage rate of artificial forestlands was significantly higher than that of secondary forestlands, but similar to those of original forestlands, fallow lands and slope farmlands. Dispersion rate of artificial forestlands was similar to that of slope farmlands, but significantly lower than those of original forestlands, secondary forestlands and fallow lands. Re-aggregation degrees of original and secondary forestlands were similar to those of fallow lands and slope farmlands, but significant higher than that of artificial forestlands. The <0.05 mm silt/clay contents of secondary forestlands, fallow lands and artificial forestlands were similar to those of original forestlands and farmlands. However, original forestlands had a significantly lower <0.05 mm silt/clay content than slope farmlands. The order of anti-soil erosion degree of 5 land use types obtained by principal component analysis was: original forestland > secondary forestland > fallow land > slope farmland > artificial forestland. It was therefore concluded that human disturbances in karst regions severely weakened soil anti-erodibility, which could be improved by leaving farmlands to fallow.

Impact of fertilization and high grain production on groundwater exploitation in Shijiazhuang Plain

LIU Zhong-Pei, ZHANG Guang-Hui, YAN Ming-Jiang, WANG Jin-Zhe

2012, 20(1): 111-115. doi: 10.3724/SP.J.1011.2012.00111

Abstract(1376) PDF(1407)

Abstract:
Shijiazhuang Plain is one of the main grain production areas in Hebei Province, cultivating mainly winter wheat and summer maize. Increased grain production in the plain is closely related with groundwater exploitation. This is because there is almost no surface runoff in the plain and winter wheat and summer maize cannot do well without irrigation. Generally, production increases with increasing groundwater exploitation. However, the rate of increase in grain production is bigger than that of groundwater recent years due to fertilization. Hence groundwater consumption intensity for wheat and maize yield is dropping. It is therefore critical to study the impact of fertilizer use on groundwater consumption in the agricultural sector. This paper analyzed the variations in groundwater exploitation for wheat and maize production. It also analyzed the effect of increased grain production on groundwater exploitation. Furthermore, the paper discussed the relationship between fertilizer use and per-unit wheat and maize yield. The results showed that increasing fertilizer use had led to decreasing groundwater exploitation for wheat and maize yield. While groundwater use was 1.86 m³·kg^-1 in the 1970s, it dropped to 0.72 m³·kg^-1 at the start of the 21^st century. According to 0.17 t·hm^-2 fertilizer use in the 1970s without considering yield-increasing effect of fertilization, groundwater exploitation sharp increased to get the total production levels of today. For example, groundwater exploitation respectively increased by 10.35×10⁸ m³, 18.88×10⁸ m³ and 20.12×10⁸ m³ in the 1980s, 1990s and 2000—2005. From the relationship between fertilizer use and per-unit wheat and maize yield, fertilizer use reached 0.76 t·hm^-2 to have the max per-unit wheat and maize yield. In the early 21^st century, however, fertilizer use per-unit area was 0.72 t·hm^-2, which was close to the 0.76 t·hm^-2 dose for max yield. Hence with increasing fertilizer use, there was little potential to increase production and decrease groundwater use.

An eco-agriculture model of “reed-crab-mandarin fish-microlepido yellowtal” for enhanced production functions of soda saline-alkali reed marshlands

YANG Fu-Yi, LI Xiu-Jun, LIU Xing-Tu

2012, 20(1): 116-120. doi: 10.3724/SP.J.1011.2012.00116

Abstract(1491) PDF(1319)

Abstract:
To explore high beneficial use of soda saline-alkali reed marshlands, an eco-agriculture model (consisting of reeds, crabs, spotted mandarin fish, and microlepido yellowtail) was developed and tested in a 23.6 hm² marshland. The model tamed and cultured crabs, spotted mandarin fish and microlepido yellowtal in saline-alkali water with natural food supply. The model also involved farmland water conservancy projects, water quantity and quality management and reeds high-output cultivation. The results for 2006—2009 showed that the outputs of crabs, spotted mandarin fish and microlepido yellowtal were 81.00 kg·hm^-2, 39.34 kg·hm^-2 and 58.62 kg·hm^-2, respectively. Reed output was 5 478 kg·hm^-2, which represented an increase of 1.2 times (22.0% per year) over natural marshlands. The total economic benefit from the model was 1.45×10⁴ Yuan per hm², an increase of 13 times over natural marshlands. Water salinity, alkalinity and soil salt content respectively declined by 19.1%, 10.3% and 20.3%. Soil organic matter content also increased by 8.9% per year. The model increased per-capita net income by 11.2% per year, which represented a contribution rate of 43% to increase of per-capita net income. The findings suggested that the model application further enhanced the functions of production and ecology of soda saline-alkali reed marshlands. The model achieved simultaneous benefits for the economy, ecology and society, and was therefore applicable to soda saline-alkali reed marshlands.

Study on spatial pattern of village-level agricultural activity based on household survey in Wugou Village, Henan Province

QIAO Jia-Jun, ZHAO Ke-Fei

2012, 20(1): 121-126. doi: 10.3724/SP.J.1011.2012.00121

Abstract(1704) PDF(1445)

Abstract:
The Johan Heinrich von Thunen’s agricultural location theory, which was based on the hypotheses of “isolated state” and “land”, was used to explain the spatial distribution of land use in China from the macro perspective. It highlighted significant differences between practical land systems and rural development in China, and applied agricultural location theory to blindly explain China’s conditions and needs. MapInfo 7.0 and ArcGIS 9.3 softwares were used in conjunction with qualitative and quantitative analyses and digital Google Maps to analyze these conditions and needs in this paper with Wugou Village of Henan Province as a case. Wugou Village did not meet “isolated state” hypothesis for the following reasons: (1) It was not only far from urban areas without agricultural trade with urban milieus, but also self-sufficient in food, vegetables and other cash crops. (2) The terrain was mountainous, different elevations with different soil fertilities, easiness of cultivation and significantly different production costs. (3) Severe droughts, little rainfalls, deep groundwater and inadequate artificial irrigation facilities. (4) Abundant population and disharmonized agricultural labor structure. (5) Fragmented land, frequent land swaps, poor land mobility, and limited agricultural production. The analysis showed that as a mountain village, the factors that influenced Wugou’s spatial layout of agricultural production were more complicated than those of the plains. Firstly, the terrain was the main factor influencing farmland distribution and vertical stratification pattern of agricultural production in the mountain village. The elevation and slope reflected the degrees of ups and downs with direct impacts on land fertility, farming difficulty and transportation cost. Secondly, land accessibility significantly determined the input-output dynamics of the mountain village’s farmlands. Thirdly, the average land share and complex terrain caused significant fragmentation of the mountain village’s agricultural lands. Hence farmlands of Wugou Village were mainly distributed along roads and circle-like expanded to both sides of road. Structure of agricultural production showed stratified pattern along altitude, forest land was mainly in land higher than the village, while vegetable and crop lands were in land lower than the village. Based on the analysis, three main bottlenecks (terrain, drought and transportation) limited the development of Wugou Village. To that end, the following recommendations were forwarded: 1) Taking measures that favor not only the local conditions but also take advantage of the terrain. Measures such as transforming the planting system to adapted mountain village with crops balanced and enhance grain-crop/cash-crop ratio. 2) Improving land use value by reforesting farmlands through national forest development programs. Fruit trees can especially serve both the purpose of forest and cash income. Animal breeding and wild plant cultivation programs can be instituted to exploit the local agricultural characteristic. 3) Artificial water conservancy facilities can be constructed to support agricultural developments using allocated state/special funds to improve irrigation systems and harvest practices. 4) Transportation systems of the village can be improved along with enhanced communication links with the outside world. 5) Transfer of land use can be made flexible via direct state policies. This can allow households to contract responsibility of their allocated lands to conversion programs such as forest cultivation. Under such policies, peasant households can change their land use in line with direct contracts to stimulate farmers’ motivation to add value to agricultural and barren hills. 6) The rich stone resource can be used to establish stone mining and processing, which can in turn absorb surplus labor and increase non-farm income.

2012 Vol. 20, No. 1