2012 Vol. 20, No. 4

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Research advances on the measurement methods for soil hydrolytic enzymes activities
2012, 20(4): 387-394. doi: 10.3724/SP.J.1011.2012.00387
Abstract(2217) PDF(4064)
Abstract:
Soil hydrolytic enzymes play an important role for maintaining carbon and nutrient cycle of ecology system as they are directly involved in the soil organic matter mineralization. The methodological differences among researchers and laboratories influenced the determining on proper measurement methods. The review summarized the research results on measuring method of soil enzymes activities involved soil storage methods, selection of substrate and incubation conditions in recent circa 20 years. To extract and purify the enzyme from soil have been left unsuccessful for the complexity of broad origin and existing states, so soil enzyme activity assays were commonly based on the quantitative evaluation of the product released or of the substrate consumed. Colorimetric methods based on artificial p-nitrophenol substrate had been used widely for the low cost. Based on the absence of the uniform international standard, and hard contrast among investigator results, the corresponding measures should be token to run measurement of soil hydrolytic enzymes activities recently. We recommended some manipulation: 1) conduct assay with fresh soil whenever possible, or soil stored shortly at 4 ℃ or -20 ℃; 2) opt substrate based on international standards and use saturated substrate concentrations to ensure Vmax being measured; 3) run the assay at a pH of buffer similar to that of soil; 4) omit inhibitors of microbial proliferation within 4 h incubation. Some research orientation currently were also suggested: 1) to enrich the research categories of soil hydrolytic enzymes; 2) develop the measurement methods of fluorimetric determination with high sensitivity, small quantity of soil sample and short incubation time; 3) establish primary standard methods by studying the catalytic kinetic of hydrolytic enzymes in typical soil types.
Soil respiration and carbon budget in black soils of wheat-maize-soybean rotation system
2012, 20(4): 395-401. doi: 10.3724/SP.J.1011.2012.00395
Abstract(1784) PDF(2127)
Abstract:
Farmlands are important terrestrial ecosystems with characteristic soil respiration and carbon budget processes. Data from the long-term experiment at Hailun Agricultural Ecology Station of Chinese Academy of Sciences for 2005—2007 were analyzed for the characteristics of crop carbon fixation, soil cumulative CO2 flux and carbon budget in the black soils of wheat-maize-soybean rotation systems. Results showed that in wheat-maize-soybean rotation system, the amount of carbon fixed by crops decreased in the order of cultivated maize in 2006 > cultivated soybean in 2007 > cultivated wheat in 2005. The averages of fixed carbon by maize, soybean and wheat were 6 513 kg(C)·hm-2, 4 025 kg(C)·hm-2 and 3 655 kg(C)·hm-2, respectively. Soil cumulative CO2 flux during crop growth seasons was highest for soybean ecosystem [average of 4 062 kg(C)·hm-2], followed by maize ecosystem [average of 3 813 kg(C)·hm-2] and then lowest for wheat ecosystem [average of 2 326 kg(C)·hm-2]. Rhizosphere derived CO2 flux accounted for about 69%~73%, 66%~80% and 46%~63% of soil cumulative CO2 flux for soybean, maize and wheat ecosystems respectively. This indicated that CO2 flux derived from crop rhizosphere was crucial for soil CO2 emission. NEP (net ecosystem productivity) was positive in black soil/crop systems of wheat-maize-soybean rotation, where farmlands served as CO2 sink from the atmosphere. NEP in different crop systems decreased in the order of maize > wheat > soybean and with averages of 3 215 kg(C)·hm-2, 1 643 kg(C)·hm-2 and 512 kg(C)·hm-2, respectively. Compared with plots without sufficient nutrients, long-term applications of chemical fertilizers (NPK) or organic manure amended chemical fertilizers (NPKOM) increased crop carbon fixation and soil cumulative CO2 flux in all cropping systems. They were highest for plots with organic manure amended chemical fertilizers (NPKOM). NEP in each cropping system was significantly affected by different fertilization treatments. NEP was highest in plots with NPK fertilizers and lowest in plots with organic manure amended chemical fertilizer (NPKOM). The findings of this study were significant for the proper management of black soils as potential carbon pools in Northeast China.
Studies on recommended fertilization methods of summer maize in different fluvo-aquic soil texture
2012, 20(4): 402-407. doi: 10.3724/SP.J.1011.2012.00402
Abstract(1396) PDF(1219)
Abstract:
Maize is the most cultivated grain crop in China. Realizing high yields of summer maize is important in ensuring food security in the country. There are, however, several known problems with summer maize production (e.g., excessive dosage and unreasonable periods of nitrogen application) that hinder high-yield realization. To increase fertilizer use efficiency and grain yield of summer maize, field experiments were conducted to determine the differences in summer maize yield, economic benefits, N, P and K use efficiency between Nutrient Expert (NE) and Agro-Services International Inc (ASI) recommended fertilizations in sand-loam, medium-loam and sticky-loam fluvo-aquic soils in Henan Province. The results showed that NE recommended fertilization treatment significantly increased maize yields in the three different soil textures. Summer maize yield, economic benefits and protein contents were all significantly different (P < 0.05) for the three soil textures and were in the order of clay-loam > medium-loam > sandy-loam soils. The output/input ratio of NE recommended fertilization treatment was higher than that of ASI recommended fertilization. Recommended fertilization treatments significant increased plant nutrient accumulation, which benefited grain protein and yield. Compared with farmer conventional fertilization (CK), maize yield increased by 7.22%, 3.84% and 11.32% for NE recommended fertilization treatment and by 13.44%, 10.60% and 11.20% for ASI recommended fertilization treatment in sandy-loam, medium-loam and clay-loam soils, respectively. N fertilizer increased yield the most under NE recommended fertilization treatment. N agronomic efficiency, use efficiencies of N, P and K fertilizers were in the order of clay-loam > medium-loam > sandy-loam. However, P and K fertilizers agronomic efficiencies were in the order of sandy-loam > clay-loam > medium-loam. Fertilizer agronomic efficiency was in the order of P fertilizer > K fertilizer > N fertilizer in all the three soil textures. NE recommended fertilization was most suitable for clay-loam fluvo-aquic soil, while ASI recommended fertilization performed best in sandy-loam and medium-loam fluvo-aquic soils.
A summer maize dressing decision-making model based on effective accumulated temperature
2012, 20(4): 408-413. doi: 10.3724/SP.J.1011.2012.00408
Abstract(1224) PDF(1586)
Abstract:
Sound judgments on crop dressing time are important technical measures?to improve the utilization efficiency of fertilizers and increase crop yield. Traditional methods of predicting crop dressing time take continuous stock of crop growth processes. These methods are, however, inaccurate and depend largely on observer experiences. Growth and nutrient accumulation processes of summer maize are closely related with accumulated temperature, light intensity, precipitation and other meteorological factors. It is therefore an effective method to build a meteorological model that precisely defines the dressing times of different crops. Field trials were conducted to study the response of crop growth and development processes to temperature, light and other meteorological factors. In this paper, effective accumulated temperature (a critical factor of crop growth and development processes) replaced growing day and was used as the step unit of Logistics model that described the levels of nutrients accumulation in summer maize. Based on the characteristics of Logistics model, three key times of summer maize nutrients accumulation were defined, which were beginning full period, full period and end full period. The decision point of dressing was then determined. The field experiments and analyses on nutrients showed that nutrient accumulation by summer maize was efficiently simulated with the established Logistics model. Comparisons suggested that the key times of beginning full period, full period and end full period of maize nutrients accumulation predicted by the accumulated temperature model was more accurate than those by the growth-day model. Validation analysis further suggested that the accumulated temperature model was innovative and practical. The growth-day model failed to sufficiently capture the full range of variability in dressing time due to regional and varietal differences. Due to difference in areas, crop variety, the established model according to a certain area was not universal. To meet this problem, the model was adjusted according to the characters, meaning of model parameters and farming practices. The modified accumulated temperature model with 11.9% n-RMSE was adaptable to any region of the world and any variety of crop to efficiently predict the optimal dressing time of farm crops. The results provided the scientific basis for rational fertilizer application with significant improvements in fertilizer utilization rates.
Nitrate loss simulated with DNDC model and control technologies in typical cropland of North China
2012, 20(4): 414-421. doi: 10.3724/SP.J.1011.2012.00414
Abstract(1451) PDF(1612)
Abstract:
Modern agricultural practices are strongly linked to fertilizer application for maintaining optimum yields. However, inefficient fertilizer use has led to a significant portion of the nitrogen (N) applied to farm fields reaching surface or underground water and atmosphere systems. The scientists from all over the world are committing themselves on improving the utilization of N fertilizer and decreasing the N leaching and N2O emissions from farmland. This paper aims to provide comprehensive management alternatives which can accommodate the needs to maintain high crop yields, to conserve diminishing natural resources, and to minimize environmental damage. The field experiment observations of N leaching, crop yields, etc., in conjunction with the local climate, soil and management information from winter wheat-summer maize rotation field, were utilized to test a process based model, Denitrification–Decomposition or DNDC, for its applicability for the cropping system, and then used the validated model to quantitatively evaluate the N loss in winter wheat and summer maize rotation croplands of North China. The optimum management practices were proposed with comprehensively consideration of the crop yield, N leaching, N2O emissions and NH3 volatilization. The results showed that the DNDC model could simulate the change of N leaching and soil residual NO3--N, NH4+-N well in winter wheat-summer maize rotation field. Moreover, the model generally had acceptable performances in the model simulations for the yield of winter wheat and summer maize. According to the model’s simulation, the amount of N loss through leaching, N2O emissions and NH3 volatilization were 49.4 kg(N)·hm-2·a-1, 17.71 kg(N)·hm-2·a-1 and 144.8 kg(N)·hm-2·a-1, respectively, in the management of traditional practices. Comprehensively analysis of the nitrogen losses, the authors put forward some optimum management practices for its applicability for local agricultural production conditions, which were to reduce 40% of conventional nitrogen fertilizer to 340 kg(N)·hm-2·a-1, to improve the 100% rate of corn straw returned to field, and to keep the conventional irrigation management practice. Compared with conventional management measures, the optimized management measures reduced 71.5% of N leaching to 14.1 kg(N)·hm-2·a-1, 15.8% of N2O emissions to 14.91 kg(N)·hm-2·a-1, and 19.1% of NH3 volatilization to 117.2 kg(N)·hm-2·a-1, and meanwhile maintained the crop yield. The evaluation results could be applied directly to the agricultural production practice.
AMMI-Biplot analysis of yield stability and test-site representativeness of proso-millet cultivars
2012, 20(4): 422-426. doi: 10.3724/SP.J.1011.2012.00422
Abstract(1600) PDF(1588)
Abstract:
The objective of this research was to study the stability of yield and test-site representativeness of proso-millet cultivars in China. Six cultivars were tested in nine sites in 10 m2 experimental plot under randomized completed block design and three replicates. The combination of double mark figure and special interaction [Dg(e)] of AMMI (additive main effects and multiplicative interaction) model was used to identify yield stability and test-site representativeness of the proso-millet cultivars. Analyzed data were from the national regional trials of proso-millet for 2006—2008. The results showed that the proportions of the sum of squares of genotype (G), environment (E) and G×E interactive effects on total sum of squares were 2.76%, 6.26% and 52.85%, respectively. There were significant effects in G action, E action and G×E interaction. IPCA1, IPCA2, IPCA3 accounted for up to 92.58% of the overall interaction effects. There were significant differences in stabilities of the six cultivars and representativeness of the nine test-sites. Among the six cultivars, “Yumi No.3” (CK) and “Yi8414-1-2-1” were high yield and better yield stability cultivars. “Gan9109-6-1-1-2” and “Gu01-391” exhibited less stability and high yield production. “Gan9133-1-3-4-1” showed to be a high-stability less-yield cultivar and “Gu02-25” was a low-yield unstable cultivar. For the nine test-sites, Fugu (Shaanxi Province), Tongxin (Ningxia Hui Autonomous Region), Yulin (Shaanxi Province) and Chifeng (Inner Mongolia Autonomous Region) had a better discrimination than Guyuan and Yanchi (Ningxia Hui Autonomous Region), Huining (Gansu Province), Wuzhai (Shanxi Province) and Eerduosi (Inner Mongolia Autonomous Region).
Effect of large-scale pig farm waste water on wheat yield and quality
2012, 20(4): 427-432. doi: 10.3724/SP.J.1011.2012.00427
Abstract(1432) PDF(1487)
Abstract:
With the rapid development of China’s large-scale pig farms, increasing manure and sewage discharge is causing severe environmental pollution that in turn threatens the sustainable development of large-scale pig farming. The utilization of sewage, a kind source of nutrient, by combined pig farming with cropping is the best solution to this problem. As sewage utilization in farmlands lacked systematic research, a field experiment was conducted to study sewage effect on yield and quality of wheat. The results of the study could provide the scientific basis for efficient wheat production that supported large-scale pig farming. The sewage used in the experiment contained 1 000 mg·L?1 of total nitrogen, 540 mg·L-1 of available nitrogen and 779 mg·L-1 of available phosphorus. The experimental treatments consisted of different combinations of sewage (0 m3·hm?2, 30 m3·hm?2, 60 m3·hm?2, 90 m3·hm?2 and 120 m3·hm?2) and nitrogen [0 kg(N)·hm?2, 30 kg(N)·hm?2, 60 kg(N)·hm?2 and 90 kg(N)·hm?2] application rates plus conventional base fertilizer at winter wheat booting stage. The results showed that wheat grain yield under 30 m3·hm?2, 60 m3·hm?2 and 90 m3 respectively. Wheat grain yield under the conventional fertilizer treatment was 8 305.52 kg·hm?2. Yield under zero-topdressing or 30 kg(N)·hm?2 nitrogen treatment was lower than that under conventional fertilizer application. This demonstrated that sewage use must be combined with certain amounts of fertilizer to get desired outputs. Grain protein content under zero-nitrogen or 30 kg(N)·hm?2 nitrogen application was below 13%, the lower limit of medium-gluten wheat requirement. Taking both yield and quality into account, combination of 60 m3·hm?2 sewage and 90 kg(N)·hm?2 nitrogen fertilizer or 90 m3·hm?2 sewage and 60 kg(N)·hm?2 nitrogen fertilizer was a suitable fertilization program. If sewage field carrying capacity and reduction in chemical fertilizer were taken as additional factors, then the combination of 90 m3·hm?2 sewage and 60 kg(N)·hm?2 nitrogen fertilizer application was most suitable for high yield, good quality and efficient wheat production in the study area.
Effects of plant polysaccharide compound agents on winter wheat photosynthetic characteristics and grain filling processes
2012, 20(4): 433-439. doi: 10.3724/SP.J.1011.2012.00433
Abstract(1383) PDF(1138)
Abstract:
Chlorophyll content, nitrate reductase activity, photosynthetic characteristics and grain-filling processes of winter wheat were investigated in a field experiment for the effects and mechanisms of three plant polysaccharide compound agents [P1 (plant polysaccharide extracted from natural plant and marine biological resources), P2 (plant polysaccharide/5-aminolevulinic acid) and P3(plant polysaccharide/5-aminolevulinic acid/dimethylpiperidinium chloride)]. The effects of agents on the growth and grain yield of winter wheat after foliage spraying at early flowering stage were determined. The results indicated that the agents increased SPAD values in flag and top second leaves. It delayed the decrease of chlorophyll content as plants development. Net photosynthetic rates of flag leaves increased by 8.7%~17.4%. Increases in SPAD and photosynthetic rate under P1 and P2 treatments were larger than those under P3 treatment. Furthermore, nitrate reductase activities increased under P1 and P2 treatments and water use efficiency (WUE) of flag leaves increased in excess of 10%. Under the compound agent treatments, the period until maximum grain-filling rate shortened by 1.3~4.2 d. Mean grain-filling rates increased by over 6% under P1 and P2 treatments. While no obvious change was noted in mean grain-filling rate under P3 treatment, grain-filling duration lengthened by 1.0 d. Whereas there was no significant change in spike number, grain number per spike and kilo-grain weight improved. Grain yield of winter wheat treated with compound agents increased by over 8% compared to the control treatment. Chlorophyll content increase, leaf senescence delay, and enhanced photosynthetic capacity and grain-filling processes improved winter wheat yield under polysaccharide compound agent treatments.
Effects of different plastic-film mulching techniques on maize (Zea mays L.) dry matter accumulation and yield
2012, 20(4): 440-446. doi: 10.3724/SP.J.1011.2012.00440
Abstract(1707) PDF(1293)
Abstract:
Plastic-film mulching is an effective yield-increasing technique in arid areas. Previous studies on film mulching have reported constant improvements in the techniques and understanding of the use of plastic-films in production systems. Different film mulching modes have different maize yield-increase effects in different areas. Field experiments were therefore conducted to determine the best plastic-film mulching technique in maize production for all regions. The effects of four plastic-film mulching techniques — full plastic-film mulching on double ridges and planting in catchment furrows (FF), half plastic-film mulching on double ridges and planting in catchment furrows (HF), flat planting with half plastic-film mulching (FN), and plastic-film mulching on ridge and planting in side film mulch (FS) — on leaf area, photosynthetic potential, dry matter accumulation, ear characteristics, grain yield and water use efficiency were compared with flat planting of zero-film mulching (CK). Cost-benefit analysis was also performed in the study. Results indicated that leaf area under FF and HF treatments significantly increased at the developmental stages but changed little under FN and FS treatments compared with CK. Photosynthetic potential also significantly increased at all stages of development under FF, HF and FS treatments. However, it was positively affected at the initial stages of growth and negatively affected at the later stages of growth under FN, FF and HF treatments. Maize ear length, diameter, row number and row grain number increased and as well lengthened ear barren tip. Although FN somewhat accelerated the increasing processes of ear length, diameter and row number and retarded that of ear barren tip, it had no obvious effect on row grain number. To some extent, FS improved ear length, row number and row grain number. However its effect on ear diameter and length of barren tip was not remarkable. All plastic-film mulching techniques increased ear grain number and 100-grain weight, but decreased ear number per plant. The highest grey correlation was noted between grain number per ear and grain yield, followed by 100-grain weight, and then by the number of ear per plant. Yield of FF, HF, FS and FN increased by 67.23%, 60.08%, 38.81% and 20.02%, respectively, compared with CK. Also water use efficiency of FF, HF, FS and FN increased by 66.43%, 59.54%, 38.35% and 19.63%, respectively, compared with CK. Economic benefit of FF, HF, FS and FN respectively increased by 85.51%, 69.58%, 36.37% and 18.69% over CK. The above findings suggested that FF treatment had the higher yield and economic advantage in the study area.
Farmland water consumption during fallow period in Shiyanghe River Basin
2012, 20(4): 447-453. doi: 10.3724/SP.J.1011.2012.00447
Abstract(1295) PDF(1019)
Abstract:
Water-storing irrigation, a widely applied irrigation method in Shiyanghe River Basin, stored redundant river or reservoir water in soil during fallow period through irrigation to provide water for the seedling growth in the next spring. Though lower evaporation in winter fallow period, the accumulative evaporation is still greater due to high evaporation during summer fallow period and high water-storing irrigation quotas. Given low water use efficiency and wasteful traditional irrigation, this paper put forward an alternative strategy for water-storing irrigation in Shiyanhe River Basin, west China. Different plough and irrigation methods were set to explore variation in soil water moisture and evaporation by using micro-lysimeter and driver 2000. Meteorological materials and other auxiliary data were also used to analyze the effects of different plough and irrigation practices on usage of soil water and rainfall. The study showed that no-tillage in autumn reduced surface soil evaporation with obvious water conservation effects. Low water-storing irrigation quotas prevented not only deep seepage, but also evaporative loss. High winter water-storing irrigation quotas caused 43.86 mm deep seepage and 121.11 mm soil moisture evaporation, laying the basis for wasteful utilization of the limited water resources. Spring plough without water-storing irrigation only caused 54.41 mm loss of water, whose water-saving effect was significant. Soil moisture loss via evaporation and deep seepage processes were in the order of traditional water-storing irrigation > low water-storing irrigation rate > autumn plough without water-storing irrigation > spring plough without water-storing irrigation. Compared with the control (CK), low rate water-storing irrigation, autumn plough without water-storing irrigation and spring plough without water-storing irrigation treatments reduced water loss by 53.44 mm, 97.52 mm and 110.56 mm, respectively. The experimental results indicated that spring plough without water-storing irrigation reduced water loss and improved water use efficiency in farmlands during fallow period in Shiyanghe River Basin.
Response of pear-jujube to different soil water potentials during budding and flowering stages
2012, 20(4): 454-458. doi: 10.3724/SP.J.1011.2012.00454
Abstract(1251) PDF(1123)
Abstract:
Pear-jujube is widely cultivated in the Loess Plateau Region (LPR) of China where it is used to reforest farmlands. Pear-jujube culture was previously constrained by wasteful use of limited water resources that characterized traditional irrigation, restricting local agricultural development. It was therefore vital to study water demand at different growth stages of pear-jujube. This paper discussed the response of 4-year-old pear-jujube trees to different soil water potentials. Both vegetative and reproductive growth processes were studied in commercial pear-jujube orchards in Mengcha Village of Mizhi County, Shaanxi Province. Four levels of soil water potentials [-31~-51 kPa, -41~-84 kPa, -59~-132 kPa and -161 kPa (no irrigation treatment)] were set up to determine suitable soil water potentials at budding and flowering stages of pear-jujube. While soil water potential was measured using the equilibrium tensiometer (EQ15), trunk diameter fluctuation was measured using the linear variable displacement transformers (LVDT). The results showed that in different soil water potentials, trunk diameter fluctuation and vegetative and reproductive growths among treatments were significantly different (P < 0.05). During the budding stage, suitable soil water potential was in the range of -41~-84 kPa, in which pear-jujube vegetative and reductive growths were flourished with the least maximum daily shrinkage (MDS) among the treatments. However, the suitable soil water potential for pear-jujube flower bud differentiation was in the range of -41~-132 kPa. Although mild water stress did not adversely affect flower bud differentiation during budding stage, vegetative growth dropped and vegetative-reproductive growth relationship optimized. As at soil water potential range of -54~-78 kPa during flowering stage, MDS dropped to lowest point while fruit setting percent was highest. The most suitable soil water potential at pear-jujube flowering stage was therefore in the range of -54~-78 kPa. Also the most suitable soil water potential for pear-jujube fruit setting was in the range of -79~-114 kPa, in which fruit setting percent was highest. Hence at flowering stage, mild water stress increased fruit setting. At budding and flowering stages, water-logging and severe water-stress limited vegetative and reproductive growths and reduced fruit setting percent. However, water-logging enhanced trunk growth and severe water-stress retarded trunk growth. Furthermore, no real need of irrigating pear-jujube at budding stage was noted during normal years. This was because precipitation was enough for sprouting, lamina opening and flower bud development. However, precipitation alone was not enough at pear-jujube flowering stage during normal years.
Response of matter production of two winter wheat genotypes with differing nitrogen efficiency to di-atmospheric CO2 concentration and nitrogen supply
2012, 20(4): 459-465. doi: 10.3724/SP.J.1011.2012.00459
Abstract(1379) PDF(951)
Abstract:
Atmospheric carbon dioxide (CO2) level continues to rise at an unprecedented rate and is expected to exceed 750 μmol·mol-1 by the end of the 21st century. Increasing atmospheric CO2 concentration has been associated to changes in global environment. The effect of elevated atmospheric CO2, as driven by global environmental change, on agricultural production remains unclear. To further clarify this effect, leaf area, plant height, biomass and yield of two winter wheat varieties (the high N efficiency “Xiaoyan22” and the low N efficiency “Xiaoyan6”) under different atmospheric CO2 (375 μmol·mol-1 and 750 μmol·mol-1) and nitrogen amendments [0, 0.15 g(N)·kg-1(soil) and 0.30 g(N)·kg-1(soil)] conditions were measured in open-top chamber (OTC) pot soil experiments. Results showed that while ear length and plant height of “Xiaoyan22” were significantly higher, leaf area and stem height were lower than those of “Xiaoyan6” for the di-atmospheric CO2 (750 μmol·mol-1) with nitrogen amended treatments. Compared with ambient atmospheric CO2 level (375 μmol·mol-1), di-CO2 concentration (750 μmol·mol-1) significantly improved yields of the two winter wheat varieties under N treatments. Yields of “Xiaoyan6” and “Xiaoyan22” were 90.5% and 52.9% greater under di-CO2 concentration with 0.15 g(N)·kg-1(soil) treatment and also 73.9% and 93.6% greater under di-CO2 concentration with 0.30 g(N)·kg-1(soil) treatment than those under the ambient CO2 condition. Di-CO2 concentration increased above-ground biomass, root biomass, total biomass, spikes per pot, grains per spike and yield of the two winter wheat varieties under the same nitrogen conditions. Although elevated N application exhibited no consistent effects on agricultural production, increasing N supply enhanced above-ground biomass, total biomass, grains per spike and yield. Above-ground biomass, total biomass, grains per spike and yield with di-CO2 condition were higher under 0.30 g(N)·kg-1(soil) treatment than under 0.15 g(N)·kg-1(soil) treatment. The results from this study indicated that increasing N supply benefited the positive effects of elevated CO2 on crop production.
Relational analysis of leaf characteristics and photosynthetic capacities of plants
2012, 20(4): 466-473. doi: 10.3724/SP.J.1011.2012.00466
Abstract(2135) PDF(2461)
Abstract:
Southeast-facing matured leaves of five plants [Viburnum odoratissimum (VO), Ginkgo biloba (GB), Oxalis triangularis cv Purpurea (OTP), Ficus elastica cv. Decora Burgundyi (FEDB) and Morus alba (MA)] were used to determine the characteristics and photosynthetic capacities of plant leaves in sunny days. The Li-Cor 6400 Portable Photosynthesis Measuring System, Modulated Chlorophyll Fluorescence System (IMAGING-PAM M-Series), Dual-PAM-100 Measuring System and conventional methods were used to analyze the relationships among leaf characteristics and photosynthetic capacities. The results showed significant differences (P < 0.05 or P < 0.01) in leaf characteristics and photosynthetic capacities among different plants. Differences in specific leaf dry weight [35~215 g (DW)·m-2] among plants were higher than those in specific leaf fresh weight [0.28~1.04 kg (FW)·m-2]. Leaf chloroplast pigment contents [chlorophyll a (Chla), chlorophyll b (Chlb), total chlorophyll (Chl) and carotenoid (Xc)] of MA and VO were the highest, followed by GB and FEDB and those of OTP were the lowest. While anthocyanin (Ant) content of OTP was maximum for 0.122 mg·g-1(FW) and 0.488 mg·g-1(DW), those of the others plants were low and similar. While OTP leaf Chla/Chlb (6.27), MA leaf Chl/Xc (9.97), MA leaf Chl/Ant (43.81) and VO leaf Xc/Ant (7.17) were the highest, OTP leaf Chl/Ant (0.49) and Xc/Ant (2.46) were the lowest. The orders of stomata conduction, transpiration rate, intercellular CO2 concentration and net photosynthetic rate (Pn) of the plants were MA > GB > OTP > VO > FEDB. MA and VO leaf practical quantum PSII [Y(II)] was the highest and that of GB was low. Although MA, OTP and FEDB PSI were high, MA and FEDB PSI photo-protection was weak and that of OTP strong. Correlation analysis indicated that the effects of Ant and Xc on Pn were insignificant. Also stomata characteristics and chlorophyll content positively regulated P>/i>n. Y(II) mainly depended on chloroplast pigment content (especially Chla) and the relationship between Y(I) and Chl/Xc was positive. Leaf stomata opening and chlorophyll content negatively regulated PSII and PSI photo-protection. It, however, positively regulated PSII photo-damage. The effect of Xc was the exact reverse of that of Chl.
Application of RBF neural network in determining soil heavy metal spatial variability
2012, 20(4): 474-479. doi: 10.3724/SP.J.1011.2012.00474
Abstract(1433) PDF(1457)
Abstract:
The Radial Basis Function Neural Network (RBFNN) was used to predict the spatial variability of Cr, Cd and Hg in the top soils of Jinyuan District, Taiyuan City. The RBFNN and Ordinary Kriging interpolation methods were compared for a more appropriate method of predicting the spatial variability of soil heavy metals. The results showed that proper spread parameter of RBFNN was critical for limiting errors and improving overall model accuracy. The optimal spread parameter values for Cr, Cd and Hg were 0.08, 0.10 and 0.14, respectively. These values were usable as the basis of reference for determining the spatial distribution of heavy metals in local farmland soils in the study area. Both the RBFNN and Ordinary Kriging interpolation methods predicted the spatial distribution of soil heavy metals with similar tendencies. Although soil Cd concentration was higher in the central region of research area (and especially in the axis from northeast to southwest), it gradually decreased from the axis to the side regions. Soil Cr concentration was also higher in the central region than in other areas. Soil Hg concentration was higher in the northeast of research area, but also gradually decreased from northeast to southwest. Generally, the spatial distributions of Cr, Cd and Hg corresponded with the sources of pollution distribution in the research area. For limited sample sizes, the RBFNN method was more sensitive and suitable for predicting the spatial distribution of heavy metals than the Ordinary Kriging method.
Vertical distribution characteristics of heavy metals in agricultural soil profiles under rice-wheat system in Heigangkou Yellow River Irrigation Region
2012, 20(4): 480-487. doi: 10.3724/SP.J.1011.2012.00480
Abstract(1555) PDF(1061)
Abstract:
Yellow River Irrigation Region (YRIR) is one of China’s important grain production bases. The contents and chemical forms of heavy metals in the agricultural soils of the region are related to sustainable agricultural development. The distribution of main soil properties [total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and CaCO33
Effect of microbial inoculants on spinach growth characteristics and soil microbial diversity
2012, 20(4): 488-494. doi: 10.3724/SP.J.1011.2012.00488
Abstract(1339) PDF(1746)
Abstract:
The Huangpu River (which is the source of drinking water) has been highly contaminated in recent years by fertilizer-rich agricultural drainage from extensive fertilizer uses in vegetable farms for high yields in the suburbs of Shanghai. A fertilizer-use reduction experiment, with 20%~40% (T1~T5) reduction in chemical fertilizer use in combination with a newly composed mixture of two lad-developed microbial inoculant strains, was used to analyze spinach growth characteristics and soil microbial population in cultivated lands of Shanghai suburbs. The microbial DNA was extracted using the specific primer GC clamp to amplify PCR and ran a denaturing gradient gel electrophoresis (DGGE). The aim of the experiments was to investigate the characteristics of spinach and soil microbial environment under reduced fertilizer use, augmented with patent microbial agents. The results showed that reduced fertilization was conducive for improving the chlorophyll content and fluorescence parameters of spinach. Compared with T1 (100% chemical fertilizer) treatment, the combined treatments of reduced chemical fertilizer and inoculants presented higher chlorophyll content and fluorescence parameters of spinach at the later growth stage but lower at latter stages. SPAD under T5 (40% reduced fertilizer with 60% inoculant) treatment, and Fv/Fm under T3 (20% reduced fertilizer and 60% inoculant) treatment were 52.856 and 0.797 respectively. The results showed that the nitrate content of the edible parts of spinach was highest under CK (without fertilizer) treatment, while those of treatments with inoculants were obviously reduced. The absorption and use efficiency of N, P and K were highest under T2 (20% reduced fertilizer with 100% inoculant) treatment. Spinach yield was increased under combined treatments of reduced fertilizer and inoculant. Spinach yield under T4 (40% reduced fertilizer with 100% inoculant) treatment was the highest, which was approximately 227.73 g·pot-1. Compared with the control (CK), yield under T4 treatment increased by 170%. Microbial richness index (from extracting total microbial DNA via PCR-DGGE and analyzing soil microbial diversity) was lowest in chemical fertilization treatment, while Shannon-Wierner index was 0.398, lower than that under CK treatment. Shannon-Wierner indexes under inoculant treatments were 0.547~0.983. The results suggested that microbial inoculants improved spinach yield, NPK uptake and use efficiency and soil microbial diversity. The combined application of 100% microbial inoculants with 40% reduction of chemical fertilizer (T4) significantly promoted spinach growth, while T3 treatment had the best effect on microbial diversity.
Henosepilachna vigintioctopunctata susceptibility to Ttripterygium wilfordii and Datura stramonium extracts
2012, 20(4): 495-500. doi: 10.3724/SP.J.1011.2012.00495
Abstract(1426) PDF(1298)
Abstract:
The influence of host plants on the larvae were investigated using the dipping and biochemical methods to determine the susceptibility of Henosepilachna vigintioctopunctata larvae that feed on eggplants, potatoes, tomatoes and nightshades to Ttripterygium wilfordii and Datura stramonium extracts and the activities of the corresponding acetylcholinesterase (AChE) and detoxification enzymes. The results indicated that LC50 values of T. wilfordii extract for larvae fed on eggplants, potatoes, tomatoes and nightshades were 1.407 9 mg·L-1, 1.595 8 mg·L-1, 1.464 7 mg·L-1 and 1.109 7 mg·L-1 and the relative toxicities were 78.82, 69.54, 75.76 and 100, respectively. LC50 values of D. stramonium extract for larvae fed on eggplants, potatoes, tomatoes and nightshades were 0.641 7 mg·L-1, 0.610 3 mg·L-1, 0.758 0 mg·L-1 and 0.488 3 mg·L-1 and the relative toxicities were 76.09, 80.01, 64.42 and 100, respectively. Compared with the susceptibility of larvae fed on eggplants, potatoes and tomatoes, the susceptibility of larvae fed on nightshades to T. wilfordii and D. stramonium extracts were significantly enhanced. The activities of AChE, glutathion-S-transferase (GST), carboxyl esterase (CarE) and mixed function oxidase (MFO) were highest for larvae fed on eggplants, followed by those fed on potatoes, tomatoes and then nightshades. Compared with AChE and GST activities of larvae fed on eggplants and potatoes, AChE and GST activities of larvae fed on tomatoes and nightshades were significantly suppressed. Also compared with CarE activity of larvae fed on eggplants, CarE activities of larvae fed on potatoes, tomatoes and nightshades were significantly suppressed. There were significant differences in MFO activity of larvae fed on the four host plants. T. wilfordii and D. stramonium extracts restrained AChE and GST, CarE and MFO activities of larvae fed on eggplants, potatoes, tomatoes and nightshades. AChE activity of larvae fed on potatoes was most significantly suppressed by T. wilfordii and D. stramonium extracts, that of AChE of larvae fed on eggplants and tomatoes was obviously suppressed and yet that of AChE activity of larvae fed on nightshades was relatively suppressed. CarE activity of larvae fed on nightshades, that of MFO of larvae fed on potatoes were significantly restrained by T. wilfordii and D. stramonium extracts. The induction or restraint of detoxification enzymes by allelochemicals in host plants were the main possible reasons for the differences in pesticide susceptibilities of H. vigintioctopunctata larvae.
Effects of coal mining subsidence on the community structure of soil macro-fauna in central China
2012, 20(4): 501-506. doi: 10.3724/SP.J.1011.2012.00501
Abstract(1381) PDF(1104)
Abstract:
Soil fauna, as an important form of soil ecosystem, can be used as a proxy for soil ecology in characterizing eco-environmental changes. Soil macro-fauna community structures in different soil ecosystems in coal mining subsidence areas of central China were investigated in the summer of 2007. A total of 477 individual soil macro-fauna were hand-collected in the field and classified into 22 families, 15 orders, 7 classes and 3 phyla. The dominant groups were araneae, coleoptera, orthoptera and hymenoptera, amounting for 83.64% of total collected macro-fauna. About four common groups accounted for 13.22% of the total fauna. Results showed a significant effect of coal mining subsidence on the individual density and group number of soil macro-fauna communities. Individual density significantly increased with increasing depth of subsidence. Change in soil eco-environment of subsidence areas triggered local migration of soil macro-fauna. Jaccard coefficient analysis showed high similarity among soil macro-fauna communities in 2 m, 4 m and 6 m depths. The lowest observed similarity was between common farmlands and bed soils of subsidence regions. The findings suggested that soil macro-fauna communities were strongly influenced by land subsidence. It was important to introduce soil macro-fauna to improve soil biological quality and assessment in subsidence farmlands.
Study on new construction land regulation in land use planning based on major function-oriented zoning
2012, 20(4): 507-512. doi: 10.3724/SP.J.1011.2012.00507
Abstract(1640) PDF(1416)
Abstract:
Land use planning lays the critical basis for land macro-control and land use regulation systems. Major function-oriented zoning planning locates state and local development directions and requirements in relation to the land use arrangement and structure in space. This in turn comprehensively promotes state or local economy and coordinates sustainable development. Based on function-oriented zoning strategies, the main function-oriented zoning index systems including the importance of eco-environment, support of social economy and land use strength were structured in this paper. The new construction land index distribution was suitable for the overall land use planning in the study area. The paper analyzed Lulong County of Hebei Province as a case study and used GIS (Geographical Information System) platform to evaluate new construction land area in different village/towns via weighted summation and “matris” with available data. Land development (D), use (U), harness (H) and protection (P) of land use were set different priorities, U-H-D-P, D-U-H-P, H-P-U-D, P-H-U-D, in which the weight of D were 0.256, 0.491, 0.148 and 0.104 respectively. And then new construction land area allocated to each village and town in the overall land use planning in Lulong County were calculated. Among the villages/towns, Liutiangezhuang, Lulong and Shimen were the important priority development towns with the most new construction land area as much as 230 hm2 and more. Other villages and towns also attained the level of indexes needed for development of urban areas. The paper coordinated land use plan and major function-oriented zoning as the breakthrough point. Compared with traditional land use planning, the new planning (based on major function-oriented zoning) to some extent overcame the subjectivity of decision makers and comprehensively coordinated sustainable ideas. The paper provided methodological basis for index distribution of overall land use planning, promoted optimal allocation of regional land resources within program limits and ensured sustainable utilization of land resources.

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