中国生态农业学报(中英文)

Cause and mechanism of winter wheat yield reduction under straw mulch in the North China Plain

CHEN Su-Ying, ZHANG Xi-Ying, SUN Hong-Yong, SHAO Li-Wei

2013, 21(5): 519-525. doi: 10.3724/SP.J.1011.2013.00519

Abstract(1540) PDF(2174)

Abstract:
In the North China Plain (NCP), winter wheat and summer maize double cropping consumed 800~850 mm of water annually. About 25%~30% of the water loss was due to soil evaporation. Reducing soil water evaporation was an effective water-saving measure in this seriously water-scarce region. Straw mulch has been proved to be one of the effective methods used to reduce soil evaporation. Double cropping of winter wheat and summer maize in the NCP was effective in producing abundant straw for mulching. With the mechanization of winter wheat harvest, winter wheat straw has been successfully used to mulch maize; significantly reducing crop water use. However, summer maize straw mulch on the soil surface has created unfavorable winter wheat growth conditions resulting in yield reduction. Because straw mulch reduced winter wheat yield, its practical application was limited. Decrease in spike number was main reason for the yield reduction of winter, and the 1000-grain weight decrease was the second reason. Soil surface straw mulch reduced maximum root zone temperature during daytime and increased minimum temperature during nighttime, thereby reducing daily temperature range. Changes in root zone temperature under straw mulch delay growth period and reduced yield. This paper summarized the causes and mechanisms of winter wheat yield reduction under straw mulch in the NCP. The results were vital in finding technical solutions to the negative effects of straw mulch on winter wheat. This enhanced the practical application of straw mulch to save irrigation water in the NCP.

Review of research progress on the influence and mechanism of field straw residue incorporation on soil organic matter and nitrogen availability

PAN Jian-Ling, DAI Wan-An, SHANG Zhan-Huan, GUO Rui-Ying

2013, 21(5): 526-535. doi: 10.3724/SP.J.1011.2013.00526

Abstract(2380) PDF(3340)

Abstract:
Straw residue incorporation, as a key practice of global organic agriculture, was critical for maintaining soil fertility, reducing fertilizer use and improving soil carbon sequestration in farmlands. Straw residue incorporation has improved farmland environments for safe and high production capacity by increasing soil organic matter and reducing nitrogen fertilizer application. Effective straw residue incorporation improved soil microbial conditions by supplying abundant carbon, stimulating microbial activity and enhancing soil fertility. Also mineralization of straw residue promoted normal soil nitrogen cycle and mineralization and improved nitrogen efficiency. Straw residue incorporation maintained normal carbon-nitrogen ratio with intensive high nitrogen input in farmland ecosystems, reduced nitrogen loss via leaching, loosened up hardened soil structures and mitigated obstacles related with continuous cropping. Recent straw residue incorporation rate in China was under 50% while it was over 90% in European and American countries. This implied that there was still plenty of room for China to make a full use of straw residue incorporation potential. Thus it was possible to improve straw residue incorporation rate in China which will gradually enhance soil organic matter content and prevent nitrogen loss and soil quality decline in farmlands. It was beneficial to refocus intensive research on the mechanisms of soil organic matter and nitrogen availability. It was also beneficial to compare long-term monitoring experiments with various technological methods of straw residue incorporation in order to develop suitable local straw residue incorporation techniques. Such efforts had the potential to promote sustainable agricultural ecosystem and agricultural production in China.

Effect of reducing fertilizer application on crop yield and nitrogen and phosphorus loss in runoff from embankment upland in Dongting Lake Region

DUAN Ran, TANG Yue-Feng, WEN Jiong, WU Cui-Xia, PENG Chang-Cheng, BAI Ling-Yu, ZENG Xi-Bai

2013, 21(5): 536-543. doi: 10.3724/SP.J.1011.2013.00536

Abstract(1976) PDF(1243)

Abstract:
A continuous 2-year maize/rape rotation experiment was conducted to study the effects of five fertilization treatments on crop yield, fertilizer use efficiency, runoff-driven N and P loss and soil N, P contents. The study also explored excess N and P in the embankment upland of Dongting Lake Region (DLR). The five treatments were conventional fertilization, 85% conventional N application, 70% conventional N application, 70% conventional N application of slow-controlled release N fertilizer plus 80% conventional P application, and 80% conventional P application. The conventional applications of N, P₂O₅ and K₂O for maize field were 400 kg·hm^-2, 90 kg·hm^-2 and 135 kg·hm^-2, respectively. Those for rape field were 180 kg·hm^-2, 65 kg·hm^-2 and 60 kg·hm^-2, respectively. The results suggested that compared with conventional fertilization, reduced fertilizer application had no obvious effect on maize and rape yield. 70% conventional N application of slow-controlled release N fertilization plus 80% conventional P fertilization significantly improved N and P fertilizer use efficiencies of maize and rape. N fertilizer use efficiencies of maize and rape during the 2-year cultivation period averagely increased by 7.96% and 4.89%, respectively. Also P fertilizer use efficiencies averagely increased by 2.02% and 2.56%, respectively. Reduced fertilizer application decreased N and P loss via runoff by about 3.54%~29.36% and 7.14%~35.71%, respectively. Compared with conventional fertilization, total soil N, P and nitrate nitrogen contents under reduced fertilizer application were insignificantly different. Reduced slow-controlled release fertilizer application had the best performance among all the treatments. The results provided useful references for reasonable fertilization, prevention/control of regional agricultural non-point source pollution and protection of the water environments of DLR.

Effects of fertilization and row spacing on microenvironment within population canopy and dry matter accumulation of waxy maize

YU Hai-Bing, WANG Jin-Shun, REN Xiang-Dong, WU Li-Wei, LIU Zheng

2013, 21(5): 544-551. doi: 10.3724/SP.J.1011.2013.00544

Abstract(1389) PDF(1029)

Abstract:
Using "Fengnuo 6" waxy maize as material, the influences of different combinations of fertilization amount (600 kg·hm^-2, 750 kg·hm^-2 and 900 kg·hm^-2) and row spacing (50 cm, 60 cm, 70 cm and 80 cm) on population canopy temperature, light intensity, relative humidity, CO₂ concentration, light/temperature distribution, as well as dry matter accumulation, growth rate, water use efficiency and cooking quality of waxy maize were studied in field trials at the same planting density. The results showed that row spacing and fertilization as well as times of the day and period of the filling stage affected waxy maize population canopy microenvironment at filling stage. Average canopy temperature was lowest at row spacing of 70 cm. During the early, middle and late periods of grain filling stage, 70 cm row spacing with 600 kg·hm^-2 fertilization amount presented the maximum values of light intensity of 236.2 μmol·m^-2·s^-1, 275.3 μmol·m^-2·s^-1 and 285.4 μmol·m^-2·s^-1, respectively. The relative canopy humidity were highest during the three periods of grain filling stage at 70 cm row spacing and 900 kg·hm^-2 fertilization amount, which were respectively higher than the minimum values by 41.99%, 33.98% and 36.11%. CO₂ concentration was highest (362.4 mg·m ^-3) at 80 cm row spacing and 600 kg·hm^-2 fertilization amount during the early period. However, during the middle and late periods, CO₂ concentration was highest at 70 cm row spacing and 600 kg·hm^-2 fertilization amount, and respectively was 363.4 mg·m^-3 and 385.7 mg·m^-3. At 70 cm row spacing and 900 kg·hm^-2 fertilization amount, water use efficiency was highest for all the three periods, which was higher by 14.75%, 15.18% and 14.46%, respectively, than the lowest value. The maximum dry matter accumulation and growth rate were highest too, with the values of 5 066.4 kg·hm^-2, 383.2 kg·hm^-22 and 13 213.4 kg·hm ^-2 for dry matter accumulation, and 14.3 kg·hm ^-2·d^-1, 15.3 kg·hm^-2·d^-1 and 19.7 kg·hm^-2·d^-1 for growth rate. The cooking quality of waxy corn (including sensory quality, smell/flavour, color, waxiness, tenderness and thinness/thickness) was also best at 70 cm row spacing and 900 kg·hm ^-2fertilization amount.

Variations in photosynthetic characteristics and yield of maize inpotato/maize intercropping systems

HUANG Cheng-Jian, ZHAO Si-Yi, WANG Ji-Chun, WANG Long-Chang, ZHAO Yong, LIAO Cai-Qin, WEI Xin, HAO Yan-Rui, CAI Ye-Mao

2013, 21(5): 552-560. doi: 10.3724/SP.J.1011.2013.00552

Abstract(1269) PDF(1078)

Abstract:
Intercropping of potato with maize has been a traditional cropping system widely practiced in the mountain regions of Southwest China. Although changes have occurred in light environment of maize due to intercropping, few reports have been analyzed the importance of competition for light and related effects on maize yield in potato/maize associations. A potato/maize intercropping field experiment with two different potato-maize row ratios was carried out to determine the dynamic changes in maize features. The features analyzed included leaf area index (LAI), special leaf weight (SLW), chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chla+Chlb) and chlorophyll a/b ratio (Chla/b) of maize at different growth stages. Also photosynthetic active radiation (PAR) and gas exchange parameters of upper and lower leaves at tasseling stage of mazie were analyzed along with yield using mono-cropped maize as the control. The respective potato-to-maize row number ratios used in the study were 2︰2 and 3︰2. The results showed a substantial drop in maize LAI at all growth stages while SLW only dropped at the early growth stages before milking under intercropping compared with monocropping. Chla, Chlb and Chla+Chlb also markedly decreased in the 3︰2 intercropping system at all growth stages while it only decreased in the 2︰2 intercropping system at seedling, jointing and silking stages. Chla/b ratio dropped at jointing stage, was subsequently enhanced at silking stage and showed no significant difference at seedling and milk stages. Compared with the 2︰2 intercropping system, the 3︰2 intercropping system had significantly lower LAI at all the growth stages except the seedling stage. Also noted were high Chla, Chlb and Chla+Chlb at all the growth stages except the milking stage, and high Chla/b ratio at silking and milking stages. SLW was not significantly different at all growth stages between 2︰2 and 3︰2 intercropping systems. Furthermore, PAR, net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and water use efficiency (WUE) declined in all treatments from upper to lower leaves of maize. Significantly lower Pn, Gs, Tr and high Ci were noted in lower leaves of maize under intercropped conditions than under mono-cropped conditions. No significant changes were noted between intercropped and mono-cropped treatments in terms of Pn, Gs, Tr and Ci of maize upper leaves. PAR in both upper and lower leaves was markedly higher in intercropping than in mono-cropping whereas no marked variations were noted in WUE of the leaves. In comparison with the 2︰2 intercropping system, the 3︰2 system showed substantially lower PAR, Gs and Tr in both upper and lower leaves, similar Pn in upper leaves and lower Pn in lower leaves. The variations in Pn, Gs and Ci suggested that intercropping limited photosynthetic activity in lower leaves of maize due to non-stomatal processes in the 2︰2 intercropping system. However, it enhanced these parameters in the 3︰2 intercropping system due to active stomatal processes. In conclusion, intercropping substantially decreased maize yield at harvest due to changes in photosynthetic characteristics in potato/maize systems. Nonetheless, the land equivalent ratios were 0.88 and 1.24 in the 2︰2 and 3︰2 intercropping systems, respectively. This suggested that there was no advantage in the 2︰2 intercropping system but there existed obvious advantages in the 3︰2 intercropping systems.

Characteristics of nitrogen metabolism in functional leaves of peanut with different yield levels

ZHAO Chang-Xing, LU Cheng-Kai, WANG Xin-Hong, WANG Yue-Fu, WANG Ming-Lun

2013, 21(5): 561-565. doi: 10.3724/SP.J.1011.2013.00561

Abstract(1272) PDF(1012)

Abstract:
An experiment was conducted under field conditions to study key enzyme activities, soluble protein (Pro) and free amino acid (AA) contents of functional leaves of peanut with different yield levels. The study aimed to specifically clarify the mechanisms of nitrogen metabolism in peanuts under super-yield conditions. The study showed that from initial flowering stage, nitrate reductase (NR) activity in peanut functional leaves gradually declined under different yield levels. NR activity in peanut functional leaves under super-yield condition was not significantly different from that under high-yield condition. However, NR activity under super-yield condition was higher than that under normal yield condition. Glutamine synthetase (GS) activity in peanut functional leaves followed a similar trend under different yield conditions, with single peak curve and the peak value occurring at pod-setting stage. GS activity in peanut functional leaves under super-yield condition was obviously higher than those under high- and normal-yield conditions. Also GS activity in peanut functional leaves under super-yield condition declined more slowly than those under high- and normal-yield conditions. During the experimental period, glutamate dehydrogenase (GDH) activity in peanut functional leaves was not regular. However, from flower-needle stage to pod-setting stage, GDH activity under super-yield condition was significantly higher than those under both high- and normal-yield conditions. During the study period, Pro and AA contents in peanut functional leaves under super-yield condition were significantly higher than those under high- and normal-yield conditions. It was concluded that the capacity of ammonia assimilation and amino acid and protein synthesis in peanut functional leaves under super-yield condition were significantly higher than those under high- and normal-yield conditions. Moreover, senescence of functional leaves under super-yield condition was slow. This delay prolonged functional leaf span in peanuts.

Impact of free air ozone concentration enrichment on cooked rice (Wuyunjing 21) texture and palatability

SONG Qi-Ling, QI Yi-Tao, ZHAO Yi-Peng, WANG Yun-Xia, LI Pan-Lin, ZHU Jian-Guo, WANG Yu-Long, YANG Lian-Xin

2013, 21(5): 566-571. doi: 10.3724/SP.J.1011.2013.00566

Abstract(1338) PDF(1380)

Abstract:
Without appropriate control of ozone precursor emissions, tropospheric ozone concentration will be projected to increase significantly by the middle of this century. Rice (Oryza sativa L.), the most important food crop, has provided nutrition for more than half of the world's population over the centuries. Elevated ozone concentration has been noted to induce a series of physiological changes in rice crop. Such changes have included changes in the processes of photosynthesis, water relation, nutrient absorption/translocation and grain filling. Such altered physiological processes due to ozone exposure have likely affected the physical and chemical properties of rice grain and thus grain quality. To date, most studies on rice response to ozone stress have focused on growth and yield with little known issues on the effects of ozone on grain quality, especially the taste of edible crops. To investigate the effects of elevated ozone concentration on the texture and taste of cooked rice, a unique free air ozone concentration enrichment (ozone-FACE) experiment was conducted in two consecutive rice growing seasons (2009 and 2010). The FACE experiment was located in Xiaoji Town in Jiangdu County of Jiangsu Province, China (119°42′0′′E, 32°35′5′′N). A native Japonica rice cultivar "Wuyunjing 21" was exposed to ambient or elevated ozone concentration of 50% above ambient value. Texture analyzer measurements showed that the hardness of cooked rice increased by 13.6% (P < 0.05) under elevated ozone concentration. Sensory analyzer evaluation of taste also showed that elevated ozone concentration respectively decreased aroma, luster, flavor, taste and integrated value by 0.8% (P > 0.1), 6.2% (P < 0.1), 2.6% (P < 0.1), 5.1% (P < 0.05) and 4.3% (P < 0.05) and increased intactness by 2.0% (P < 0.05). While the yearly effect was significant for all texture and taste variables of cooked rice, the interaction between year and ozone was in the most cases not detected. The above results suggested that rice grown under future high ozone environments will have greater hardness and deteriorated taste properties after cooking.

Flower induction and physiological response of Citrus reticulata "Shatangju" to low temperature under solar greenhouse condition

FU Chong-Yi, LIU Jie-Cai, CUI Shi-Mao, BAO Yan-Yan, REN Jie, HAO Chun-Yan

2013, 21(5): 572-579. doi: 10.3724/SP.J.1011.2013.00572

Abstract(1428) PDF(1289)

Abstract:
Open-field cultivation has been the main mode of citrus cultivation in China, with major blooming peak in spring and citrus fruits only shipped to markets in October through December. Under protected cultivation, it was possible to force the flowering stage of citrus to an advanced date via temperature control for earlier shipments of fruits to markets. In north China, early autumn low temperatures in solar greenhouses have been used to induce early citrus flower bud differentiation. Induction of flowers by the warming effect with plastic film covers forced sprouting. While the role of the low temperature in flowering has been well documented, flower bud differentiation competence during winter under greenhouse conditions has remained unconfirmed. To determine suitable heating time for citrus flower bud morphological differentiation in solar greenhouse, 4-year-old of "Shatangju" tangerine (Citrus reticulata "Shatangju") seedlings with stock of trifoliate orange (Poncirus trifoliate Raf.) were selected. The response of the "Shatangju" tangerine flower to low temperature in solar greenhouse was studied in an in vitro culture. The results showed that some axillary buds differentiated into flower buds after treated with low temperature (15 ℃ at day for 12 h, 10 ℃ at night for 12 h) for 720 hours. Floral ratio apparently decreased while germination ratio sharply increased after 960 hours under low temperature. Floral ratio was negatively correlated with germination ratio. Under solar greenhouse conditions, autumn shoots of "Shatangju" tangerine were ripe enough to form flower buds in early November. Floral ratio apparently increased during the whole of winter, which showed order of average floral ratio: February > January > December. When accumulated time of low temperature 5~20 ℃ reached 1 309 hours, floral ratio stabilized at 40.51%. A significantly negative correlation was noted between leafy to leafless flower ratio and accumulated hours of <5 ℃. Under low temperature treatment, C/N ratio was positively correlated with floral ratio while proline content showed a highly significant positive correlation with floral ratio. The response of the change in C/N ratio and proline content of "Shatangju" tangerine was positive to flower induction. In conclusion, change in C/N ratio and shoot proline content were good indicators for heat treatment of citrus to force flower bud germination.

Regional differences in soil nutrient content along the forest edge in the northern slope of Tianshan Mountains

Muyessar·TURDI, Jilili·ABUDUWAILI, JIANG Feng-Qing

2013, 21(5): 580-589. doi: 10.3724/SP.J.1011.2013.00580

Abstract(1183) PDF(965)

Abstract:
In this study, field investigation and laboratory analyse were carried out to gain a comprehensive insight into five kinds of soil nutrients (organic matter, available nitrogen, available phosphorus, available potassium and total salt) in three sections of the northern slope of Tianshan Mountains - the Zhaosu-Tekesi, Xinyuan-Bayinbuluke and Balikun-Yiwu sections. Multivariate statistical analysis method was used to study the characteristics of nutrient distribution in different soil profile layer (0~5 cm, 5~20 cm, 20~40 cm) in different sections of the northern slope of Tianshan Mountains. According to the standard of the Second National Soil Survey, variational characteristics of fertility and nutrient contents of different soil profiles in the sections were analyzed. Also variations in soil nutrient contents were clarified. Furthermore, quantitative comparison of nutrient contents among different sections was performed. The results showed that soil samples collected from the western sections (Zhaosu-Tekesi and Xinyuan-Bayinbuluke) had much higher nutrient contents than those from the eastern section (Balikun-Yiwu) of the northern slope of Tianshan Mountains. There were obvious differences in contents of organic matter, available nitrogen, available phosphorus and available potassium in the soil layers among different depths in the three sections. The average contents of organic matter, available nitrogen, available phosphorus and available potassium in the 0~5 cm soil layer were higher than those in the 5~20 cm and 20~40 cm soil layers. Also these variables were higher in the 5~20 cm soil profile layer than in the 20~40 cm soil profile layer. However, total soil salt content was not significantly different vertically across the soil profile. Based on the Second National Soil Survey standard, soils on the northern slope of Tianshan Mountains were relatively fertile. While changes in the amounts of soil nutrient contents in the 0~5 cm, 5~20 cm and 20~40 cm soil layers in Zhaosu-Tekesi and Xinyuan-Bayinbuluke sections followed a certain regular pattern, which in Balikun-Yiwu section was irregular. In most part of the western part of the northern slope (Zhaosu-Tekesi, Xinyuan-Bayinbuluke) is large summer pastures with various vegetations and hgiher vegetation coverage, where soils is fertile. It was recommend to protect the soils from overgrazing and random perturbations in order to avoid soil erosion. It was also critical to ban setting up of exploration platforms in larger slope areas. Also the low vegetation cover and gravel soil in the east part of the northern slope (Balikun-Yiwu) induced lower soil nutrient content comparing to the west part. It was therefore important to maintain original habitats and avoid anthropogenic disturbances that could induce habitat degradation.

Soil hydrological function at different vegetation restoration stages in purple soil slopelands in Hengyang

CHEN Jing, YANG Ning

2013, 21(5): 590-597. doi: 10.3724/SP.J.1011.2013.00590

Abstract(1704) PDF(1295)

Abstract:
Soil hydrological functions at different vegetation restoration stages in purple soil slopelands in Hengyang were explored by using spatial series in replace of temporal series. The results showed significant increases (P < 0.05) in soil water storage capacity and permeability from bare-land (CK) to grassland stage (Ⅰ), bushwood and grassland stage (Ⅱ), bushwood (Ⅲ) and to arbor and bushwood stage (Ⅳ). The orders of initial and stable infiltration rates were respectively arbor and bushwood stage (IV) (1 347.09 mm·h^-1 and 338.00 mm·h^-1) > bushwood stage (III) (876.98 mm·h^-1 and 323.30 mm·h^-1) > bushwood and grassland stage (II) (834.99 mm·h^-1 and 320.64 mm·h^-1) > grassland stage (I) (729.09 mm·h^-1 and 306.18 mm·h^-1) > bare-land stage (CK) (412.43 mm·h^-1 and 122.98 mm·h^-1). The fitness of Horton infiltration model derived for soil infiltration at each stage was strong (R² ≥ 0.765), and the model was highly applicable. Soil infiltration capability was greatly affected by soil physio-chemical properties and root system. Fine roots (≤ 1 mm in diameter) was effective in improving soil physio-chemical properties, and soil infiltration capability increased with increasing density of the fine roots. Principal component analysis (PCA) showed that from bare-land stage to grassland stage, bushwood and grassland stage, bushwood stage to arbor and bushwood stage, hydrological properties significantly increased (P < 0.05). The order of comprehensive hydrological function was arbor and bushwood stage (IV) (57.45) > bushwood stage (III) (48.54) > bushwood and grassland stage (II) (40.68) > grassland stage (36.81) (I) > bare-land stage (CK) (31.43). The study enriched and broadened vegetation ecology and ecological restoration in the area. It also provided the critical basis for vegetation restoration and reconstruction of ecosystem in purple soil slopelands in Hengyang.

Effect of tillage systems on community structure of soil mites

ZHAN Li-Li, XU Yan-Li, ZHANG Xing-Yi, PEI Xi-Chao, ZHAO Gang, WANG Jian-Hua

2013, 21(5): 598-605. doi: 10.3724/SP.J.1011.2013.00598

Abstract(1324) PDF(887)

Abstract:
Soil mites has been used as an important bio-indicator of soil ecosystem. An experiment was set up to determine the effects of tillage systems on individual number, family number, community structure and vertical distribution of soil mites. The experiment was conducted at the National Observation Station of Hailun Agroecology System in Northeast China. The tillage systems used for the experiment included no-tillage, limited tillage, moldboard plough, combination tillage and rotary tillage. Soil samples were collected from 0~15 cm soil layer under different tillage systems in May, June and July of 2009 and modified Tullgren method used to extract soil mites from the soil samples. The individual and family numbers were significantly affected by different tillage systems. A total of 2 441 soil mites were captured in the study. There were respectively 366, 436, 553, 819 and 267 soil mites under no-tillage, reduced tillage, combination tillage, rotary tillage and moldboard plough, corresponding to 13, 18, 13, 14 and 11 families under each tillage system. The highest individual number of soil mites was in rotary tillage field while the highest family number of soil mites was in limited tillage field. The vertical distribution of soil mites was affected by different tillage systems and sampling times. With the exception of no-tillage, there was faunal accumulation in the soil surface layer in May under the tillage systems. The individual number of soil mites was significantly higher in the 0~5 cm soil layer than in the 5~10 cm and 10~15 cm soil layers (P < 0.05). Also faunal accumulation in the soil surface layer at all the three sampling times was noted under combined tillage and limited tillage systems. Soil mites diversity was preserved under limited tillage. MGP analysis showed that the composition of soil oribate mites changed with season. The dominant family of soil oribate mites changed from senior oribate to junior oribate mites, which was more obvious under no-tillage and limted tillage than the other tillage systems. While the composition type of soil oribate mites was P, G and O under limited tillage at the three sampling times, it was P, O and G under no-tillage system. Conservation tillage systems (i.e., no-tillage and limited tillage) better preserved community diversity and stability of soil mites than the other tillage systems. Conservation tillage was also protective for soil environment.

Screening of virulence-attenuated strains for Fusarium oxysporum f. sp. cucumerinum after treatment with parsley fresh root extract

QIAN Cheng, YUN Xing-Fu, GAO Xiao-Min, BAO Yan-Yan, ZHANG Dong-Dong, LI Jie, WANG Yong

2013, 21(5): 606-614. doi: 10.3724/SP.J.1011.2013.00606

Abstract(1143) PDF(958)

Abstract:
Previous studies have shown that parsley extracts from fresh roots, rotten roots, rhizospheric soils, rhizospheric rotten soils, seed or volatiles have allelopathic effects on Fusarium oxysporium f. sp. cucumerinum (Foc). Different parsley extracts had different allelopathic effects on Foc and were related to extract concentration and action time. In terms of time-invariance, allelopathic effects increased with increasing concentration of different extracts. However, in terms of concentration, allelopathic effects weakened with prolonged duration of action of different extracts. Other studies have noted that different extracts (ethanol, acetone and distilled water) of fresh parsley roots inhibit mycelia growth of Foc, reduce the number of pathogenic spores and limit spore germination rate. Did treatment of Foc with successive generations of different parsley fresh root extracts always resulted in allelopathic inhibition of pathogens? Did any such allelopathic inhibition influence Foc virulence? Based on the above issues, the effect of fresh parsley root extract on Foc growth and pathogenicity were studied in laboratory antifungal experiments and artificially inoculated potted cucumbers in greenhouse conditions. In the first part of the study, Fusarium colonies were treated with 50 mg·mL^-1 of fresh parsley root extracts respectively in acetone, ethanol, distilled water and the corresponding control, and colony diameters assessed for 5 generations. Compared with the control, both acetone and ethanol extracts had lower colony diameter after continuous assessment for 5 generations. Aqueous extracts had lower colony diameters than the control only in the 3^rd generation. Both inhibition and promotion of allelopathy on Foc were expressed in the other generations. In the second part of the study, each generation of treated Foc strains was used to inoculate cucumber in order to determine their pathogenicity. After 7 days, disease index was assessed on the seedlings. The results showed that fresh parsley root acetone, ethanol and distilled water extract treatments had lower disease index than the control after 5 continuous generations of inoculation. It also had attenuation effect on Foc virulence. Foc virulence gradually decreased with increasing subculture generation. By the time when the 5^th generation strain was inoculated, disease index of acetone extract dropped to 0. It also had the greatest attenuation of virulence and colonial morphology change. Colony color changed from white to lavender and colony density dropped from dense to sparse. The study screened virulence-attenuated Foc strain through fresh parsley root extracts under continuous processing.

Response of antioxidant system and vascular bundle browning to tomato Fusarium wilt

YAN Min, PANG Jin-Mei, JIAO Xiao-Yan, GUO Jun, WU Ai-Lian

2013, 21(5): 615-620. doi: 10.3724/SP.J.1011.2013.00615

Abstract(1207) PDF(882)

Abstract:
To facilitate early diagnosis and identification of tomato wilt disease caused by Fusarium oxysporum, tomato seedlings were cultured in liquid medium, and their vascular bundle browning and antioxidative system response after infection with different concentrations of F. oxysporum were investigated. Five concentrations of F. oxysporum - B1 (10⁴ cfu·mL^-1), B2 (10⁶ cfu·mL^-1), B3 (10⁷ cfu·mL^-1), B4 (10⁸ cfu·mL^-1) and CK (the control without pathogenic bacteria) - were used in the study. The antioxidant system variations and vascular bundle browning were assessed after 4, 8, 12, 16 and 20 days of inoculation. The results showed that under hydroponic conditions, vascular bundle browning occurred at 16 days after inoculation with F. oxysporum. Browning severity was positively correlated with inoculant concentration. Vascular bundle pathogen content was detected only under B4 treatment. Melonaldehyde (MDA) content of tomato leaves initially decreased followed by an increase with the passage of time. It started rising gradually on day 12 and reached the maximum on day 20 after inoculation. MDA contents in inoculation treatments were higher than the control and B4 treatment was significantly higher than the other treatments. Peroxidase (POD) activity initially decreased slowly but picked up 12 days after inoculation, followed by a sharp rise under inoculant concentration of 108 cfu·mL^-1. Polyphenol oxidase (PPO) activity increased gradually until reaching its peak value 16 days after infection. MDA content and activities of POD and PPO increased with increasing inoculant concentration, and were highest at inoculant concentration of 10⁸ cfu·mL^-1, which respectively were 13.1, 12.9 and 1.9 times of the un-inoculated control. No changes were observed in catalase (CAT) activity within the entire culture experiment. CAT activity of control treatment was higher than that of inoculation treatments, and was not affected by F. oxysporum inoculation. When combined with vascular bundle browning, MDA content and POD and PPO activities were important indicators for early diagnosis of tomato Fusarium wilt.

Characteristics and selection of efficient lignocellulose degradation microbial community

WANG De-Wu, YAO Tuo, YANG Qiao-Li, QI Guo-Tao, LIU Xin-Yi, GUN Shuang-Bao

2013, 21(5): 621-627. doi: 10.3724/SP.J.1011.2013.00621

Abstract(1240) PDF(1069)

Abstract:
Soil acidification or alkalization has been a serious global environmental problem. It has not only caused huge losses of agricultural production, but also has been a seriously threat to ecological environment. Therefore, a simple and effective soil improvement method was critical for environmental protection and agricultural production. A group of lignocellulose microbial community was selected from soil samples of cattle and chicken feces compost. The selection was based on restrictive training in an effort to get a group of microbial population with the potential to improve soil acidity and alkalinity. The ability of the microbial system adapting to different initial pH, fiber degradation and salt-tolerance was investigated as well. The results suggested that the pH of culture medium (utilized filter paper, corn straw, rice straw and wheat straw as carbon limiting source) changed sharply and tended towards neutrality when inoculated in a wide pH range (pH of 5.0~11.0) within 6 days. The rates of weight loss of filter paper, corn straw, rice straw and wheat straw respectively exceeded 93.15%, 50.53%, 44.29% and 42.60% within 7 days of cultivation. When filter paper was used as the sole carbon source at 2.0% salt stress, the rate of weight loss was 84.82% after 7 days of cultivation. This suggested that lignocellulose degradation microbial community had the capability to adapt and regulate pH and effectively degrade lignocellulose materials under culture conditions. Additionally, the microbial community had certain degree of salt resistance. Therefore lignocellulose microbial community had the potential to improve soil acidity and alkalinity.

Evaluation of ecological land based on RS and GIS: A case study of Dawa County, Liaoning Province

WANG Shi-Dong, SHEN Li, WANG Xin-Chuang

2013, 21(5): 628-637. doi: 10.3724/SP.J.1011.2013.00628

Abstract(1400) PDF(1207)

Abstract:
With increasing calls for environmental quality in recent years, "ecological land" emerged as a specific term in related government documents on land-use planning and environmental protection. This term was put forward to forge a harmony among the development of natural resources, human society and ecosystem. Ecological land is a kind of land with significant ecological services that are crucial for directly/indirectly protecting regional ecological environment and improving regional man-land relationship. In land-use planning, ecological lands with significant eco-service functions were protected. This avoided possible regional eco-environmental issues at certain levels of eco-security, protected regional eco-environments and improved man-land relationship. As such, interests have grown in ecological land evaluations, argued as an important phenomenon in the domain of ecological and environmental protection and land-use planning. Based on natural conditions, socio-economic status, land-use characteristics and ecological protection requirements of the study area, a classification system of ecological land according to eco-services was constructed. On the basis of the system, an ecological land evaluation index system was established. The weights of the evaluation factors were calculated using the AHP (Analytic Hierarchy Process) approach and expert knowledge. The evaluation units were divided and then the ecological land of Dawa County was evaluated using the weighted exponent approach based on RS and GIS. The results showed that the ecological land of Dawa County was classified into three categories - forbidden land development, restricted land development and optimized land development. The ecological land areas of forbidden development, restricted development and optimized development were 14 696 hm², 25 185 hm², and 14 282 hm²; accounting for 27.1%, 46.5% and 26.4% of the total ecological land respectively. Each of the three types of ecological land had its unique characteristics that required protection by adopting corresponding measures. This study will provide data-driven decision-making for regional ecological land protection, improve ecological environment, coordinate man-land relationship and revise land-use planning.

Leaf area index and standard error of pine forests estimated with common digital camera

XU Zhang-Hua, LIU Jian, YU Kun-Yong, GONG Cong-Hong, XIE Wan-Jun, TANG Meng-Ya, LAI Ri-Wen, LI Zeng-Lu

2013, 21(5): 638-644. doi: 10.3724/SP.J.1011.2013.00638

Abstract(1219) PDF(827)

Abstract:
Both leaf area index (LAI) and standard error (SEL) have been used as important structural variables of vegetation. These variables have been used as reference data in the performance of forest management, pest control and quarantine. Several studies have reported retrieval of LAI but few have retrieved the related SEL, another significant index in sustainable forest management. This study proposed a method for the applications of LAI and SEL measured with testers in complex conditions. In the study, pictures of pine forest canopy were taken with a common digital camera. The pictures were used to calculate two forest indicators - leaf coverage (Cover) and leaf coverage standard deviation (Cover SD) - via 2G B characteristic index. The correlation models of LAI-Cover and SEL-Cover SD were constructed, from which LAI and SEL of the pine forest were estimated. The results showed highly significant positive correlations between leaf coverage and LAI, and then between leaf coverage standard deviation and SEL. The analysis showed that it was possible to accurately estimate the indexes of pine forests from the models LAI = 0.1926e ^3.0955cover (R² = 0.613 5) for LAI and (R² = 0.493 5) for SEL. The estimation accuracy reached 0.894 6 and 0.798 5, respectively. It was therefore highly feasible and accurate to estimate LAI and SEL of pine forests using common digital cameras. This gadget does not require much outside light conditions and is very convenient, especially in restricted measurement conditions. The proposed method was suitable for solving inaccuracy measurement issues and saving manpower and material resources. Thus it was concluded that the method should be given high-profile promotion to facilitate a wide application.

2013 Vol. 21, No. 5