Effects of Different Nitrogen Fertilizer Levels and Native Soil Properties on Rice Grain Fe, Zn and Protein Contents

Deposition of protein and metal ions （Fe, Zn） in rice grains is a complex polygenic trait showing considerable environmental effect. To analyze the effect of nitrogen application levels and native soil properties on rice grain protein, iron （Fe） and zinc （Zn） contents, 32 rice genotypes were grown at three different locations each under 80 and 120 kg/hm2 nitrogen fertilizer applications. In treatments with nitrogen fertilizer application, the brown rice grain protein content （GPC） increased significantly （1.1% to 7.0%） under higher nitrogen fertilizer application （120 kg/hm2） whereas grain Fe/Zn contents showed non-significant effect of nitrogen application level, thus suggesting that the rate of uptake and translocation of macro-elements does not influence the uptake and translocation of micro-elements. The pH, organic matter content and inherent Fe/Zn levels of native soil showed significant effects on grain Fe and Zn contents of all the rice genotypes. Grain Zn content of almost all the tested rice genotypes was found to increase at Location III having loamy soil texture, neutral pH value （pH 6.83） and higher organic matter content than the other two locations （Locations I and II）, indicating significant influence of native soil properties on brown rice grain Zn content while grain Fe content showed significant genotype × environment interaction effect. Genotypic difference was found to be the most significant factor to affect grain Fe/Zn contents in all the tested rice genotypes, indicating that although native soil properties influence phyto-availability of micronutrients and consequently influencing absorption, translocation and grain deposition of Fe/Zn ions, yet genetic makeup of a plant determines its response to varied soil conditions and other external factors. Two indica rice genotypes R-RF-31 （27.62 μg/g grain Zn content and 7.80% GPC） and R1033-968-2-1 （30.05 μg/g grain Zn content and 8.47% GPC） were identified as high grain Zn and moderate GPC rice genotypes. These results indicate that soil property and organic matter content increase the availability of Fe and Zn in rhizosphere, which in turn enhances the uptake, translocation and redistribution of Fe/Zn into rice grains.

PERFORMANCE AND PERSISTENCE OF GREEN FLUORESCENT PROTEIN (gfp) MARKED AZOTOBACTER CHROOCOCCUM IN STERILIZED AND UNSTERILIZED WHEAT RHIZOSPHERIC SOIL

The persistence and performance (growth promoting potential) of green fluorescent protein (gfp) marked Azotobacter chroococcum strain ABR 4G were studied in sterilized and unsterilized wheat rhizospheric soil. The gfp was integrated via Tn 5 transposition into A. chroococcum chromosome and the resultant gfp marked colonies were identified by green fluorescent emission under UV light. The gfp was stably maintained in A. chroococcum and the gfp insertion had no apparent adverse effect on the growth promoting properties of the marked soil isolate ABR 4G. The growth promoting properties (nitrogen fixation, ammonia excretion, phosphate solubilization and IAA production) of the parent soil isolate and the gfp marked strain were found to be almost the same. All the quantitative wheat plant traits were significantly influenced by inoculation of A. chroococcum ABR 4G strain in sterilized and unsterilized soil. Inoculated bacterial counts increased gradually in wheat rhizosphere, reached maximum on 60 th d and declined on 80 th d. Fertility levels also affected survival of marked strain and the survival was comparable in sterilized and unsterilized soil. The growth promoting properties were also determined from the marked strain reisolated from wheat rhizosphere in both types of soil. Fig 1, Tab 2, Ref

Variation in glomalin in soil profiles and its association with climatic conditions,shelterbelt characteristics,and soil properties in poplar shelterbelts of Northeast China

Glomalin-related soil protein(GRSP)sequesters large amounts of carbon and plays important roles in maintaining terrestrial soil ecosystem functions and ecological restoration;however,little is known about GRSP variation in 1-m soil profiles and its association with stand characteristics,soil properties,and climatic conditions,hindering GRSP-related degraded soil improvement and GRSP evaluation.In this study,we sampled soils from 1-m profiles from poplar(Populus spp.)shelterbelts in Northeast China.GRSP contents were 1.8–2.0 times higher in the upper 40 cm soil layers than at 40–100 cm.GRSP-related soil organic carbon(SOC)sequestration in deeper soil layers was*1.2 times higher than in surface layers.The amounts of GRSP-related nutrients were similar throughout the soil profile.A redundancy analysis showed that in both surface and deeper layers,soil properties(pH,electrical conductivity,water,SOC,and soil nutrients)explained the majority of the GRSP variation(59.5–84.2%);the second-most-important factor in GRSP regulation was climatic conditions(temperature,precipitation,and altitude),while specific shelterbelt characteristics had negligible effects(<5%).Soil depth and climate indirectly affected GRSP features via soil properties,as manifested by structural equation model analysis.Our findings demonstrate that GRSP is important for carbon storage in deep soils,regardless of shelterbelt characteristics.Future glomalin assessments should consider these vertical patterns and possible regulating mechanisms that are related to soil properties and climatic changes.

Effects of organic mulching on soil aggregate stability and aggregate binding agents in an urban forest in Beijing, China

Urban forest soil is often disturbed by rapid urbanization. Organic mulching is effective for improving soil quality and aggregate stability. This study evaluated how soil binding agents changed aggregate stability through organic mulching in urban forest soils. Three treatments were applied in Jiufeng National Forest Park, Beijing: (1) no organic mulch (control);(2) wood chips alone (5 cm thickness);and, (3) wood chips + wood compost (This mulch was divided into two layers, the upper layer of wood chips (2.5 cm), the lower layer wood compost (2.5 cm)). Soil samples were collected from the surface 10- cm soil layer and fraction into four aggregates. Glomalin-related soil protein and soil organic carbon were measured in bulk soil and the four aggregates. The results show that wood chips + wood compost increased the proportion of large and small macroaggregates, mean weight diameter and geometric mean diameter. The total and easily extractable glomalin-related soil protein were higher in the wood chips + wood compost. However, soil organic carbon was lower in the wood chips alone application compared to the controls and wood chips + wood compost. Easily extractable / total glomalin-related soil protein and glomalin-related soil protein / soil organic carbon ratios of wood chips alone and wood chips + wood compost had increased trend compared to the controls but did not reach significant levels (p > 0.05). Mean weight diameter and geometric mean diameter correlated positively with total and easily extractable glomalin-related soil protein but were not positively correlated with soil organic carbon, the ratios of easily extractable and total glomalin-related soil protein, and the ratios of glomalin-related soil protein and soil organic carbon. Redundancy analysis revealed that total glomalin-related soil protein was the most important driver for soil aggregate stability, especially the total glomalin-related soil protein of small macroaggregates. The results suggest that wood chips + wood compost enhanced soil aggregate stability through the increase of glomalin-related soil protein. Wood chips alone cannot enhance soil aggregate stability in urban forests in the short term.

AM真菌接种和生草刈割对盆栽初生枳生长和土壤结构的影响

在温室中,研究了盆栽基质接种丛枝菌根(arbuscular mycorrhiza,AM)真菌摩西管柄囊霉Funneliformis mosseae对初生(种子播种育苗2个月后的幼苗)枳Poncirus trifoliata生长、菌根侵染、菌丝长度、土壤球囊霉素相关土壤蛋白(GRSP)含量和土壤结构的影响;同时研究了在AM真菌接种和柱花草间作条件下柱花草刈割对初生枳和柱花草生长、菌根侵染、土壤GRSP含量和土壤结构的影响。结果表明,与不接种相比,接种AM真菌显著地促进了初生枳生长,增加了土壤GRSP含量,并且土壤结构也得到改善。在AM真菌接种与柱花草间作的相同条件下,与柱花草未刈割相比,柱花草刈割对初生枳生长、菌根侵染、土壤GRSP含量和土壤结构均无显著性影响,但柱花草未刈割处理的菌丝长度是刈割处理的2.5倍。相关性分析表明,根际土壤大团聚体显著地与菌根侵染率、土壤GRSP含量和菌丝长度正相关,而生草刈割影响了丛枝菌根真菌菌丝长度,可能对土壤结构有不利影响。

等高反坡阶措施下坡耕地球囊霉素相关土壤蛋白对土壤碳氮储量的贡献

为证实坡面微地形改造措施—等高反坡阶(CRT)对坡耕地的生态修复功能,揭示CRT对球囊霉素相关土壤蛋白(GRSP)含量及土壤碳氮储量贡献的影响与机制至关重要。通过分析原状(CK)和CRT处理下旱季和雨季坡耕地0—5、5—15、15—30 cm土层中总GRSP(T-GRSP)、易提取GRSP(EE-GRSP)、土壤有机碳(SOC)与土壤全氮(TN)在CRT阶上和阶下及CK对应位置处的时空分布特征,探讨CRT措施下GRSP对土壤碳氮储量的贡献,揭示相关机制。结果表明:(1)CRT坡耕地土壤T-GRSP、EE-GRSP、SOC和TN的含量较CK显著提高(P<0.05),增幅分别为16.6%—189%、7.28%—102%、1%—68.3%和7.29%—79.7%。且CRT对坡耕地GRSP含量的提升效果总体表现为雨季强于旱季、表层(0—5 cm)土壤高于深层(15—30 cm)、阶下优于阶上。(2)相比CK,CRT坡耕地旱季和雨季SOC储量分别提高8.06%和13.5%,TN储量提高7.01%和12.1%。T-GRSP对SOC和TN储量的贡献率较CK分别提高8.5%—141%和2.58%—133%,EE-GRSP对SOC和TN储量的贡献率较CK分别提高1.38%—82%和5.25%—87.2%。且CRT对坡耕地SOC和TN储量提升效果雨季优于旱季,对表层土壤T-GRSP对SOC和TN贡献率的提升效果表现为雨季强于旱季、阶下强于阶上。(3)CRT极大提高了坡耕地T-GRSP与土壤孔隙度、SOC和TN的正相关性。相比CK,相关系数(R~2)分别由0.17、0.26和0.29增至0.51、0.66和0.64。因此,CRT措施不仅降低了坡耕地SOC和TN的流失,还通过提高有机质含量改善土壤通气透水性,进而提高坡耕地GRSP的分泌与累积,同时提高GRSP对碳氮的贡献率,促进了土壤碳氮的固持与封存。

施肥和豆禾混播对松嫩平原退化草地修复的影响

【目的】探索适合松嫩平原中度退化草地的最佳修复模式,为松嫩平原退化草地的保护修复提供技术支持。【方法】设置紫花苜蓿(Medicago sativa)与羊草(Leymus chinensis)2种混播比例,结合不同N施用量,分析土壤养分含量、牧草品质和产量之间的关系。【结果】施肥水平显著影响群落物种丰富度(P<0.01),施肥水平、混播比例及二者交互显著影响土壤有机质、Shannon⁃Wiener多样性指数、牧草粗蛋白含量及产量(P<0.05)。土壤全氮、牧草粗蛋白含量与施氮量存在极显著正相关性(P<0.01)。两种混播比例下,土壤全氮含量变化与N施用量一致;N施用量300 kg/hm2的牧草粗蛋白含量高达20.22%,与其他处理差异显著(P<0.05)。【结论】N施用量200~250 kg/hm2在试验当年秋季和第二年春季均获得最佳产量;豆禾1∶2混播的群落丰富度和多样性优于2∶2混播,其中N施用量150 kg/hm2表现最佳。

Arbuscular mycorrhizal fungi ameliorate the chemical properties and enzyme activities of rhizosphere soil in reclaimed mining subsidence in northwestern China

In semi-arid region of northwestern China, underground mining subsidence often results in decreased vegetation coverage, impoverishment of soil fertility and water stress. In addition, the physical-chemical and biological properties of soil also change, resulting in more susceptible to degradation. In particular, subsidence causes disturbance of the symbioses of plant and microbe that can play a beneficial role in the establishment of vegetation communities in degraded ecosystems. The objective of this study was to evaluate the effects of revegetation with exotic arbuscular mycorrhizal fungi(AMF) inoculum on the chemical and biological properties of soil over time in mining subsidence areas. Soils were sampled at a depth up to 30 cm in the adjacent rhizosphere of Amorpha fruticose Linn. from five reclaimed vegetation communities in northwestern China. In August 2015, a field trial was set up with five historical revegetation experiments established in 2008(7-year), 2011(4-year), 2012(3-year), 2013(2-year) and 2014(1-year), respectively. Each reclamation experiment included two treatments, i.e., revegetation with exotic AMF inoculum(AMF) and non-AMF inoculum(the control). Root mycorrhizal colonization, glomalin-related soil protein(GRSP), soil organic carbon(SOC), soil nutrients, and enzyme activities were also assessed. The results showed that mycorrhizal colonization of inoculated plants increased by 33.3%–163.0% compared to that of non-inoculated plants(P<0.05). Revegetation with exotic AMF inoculum also significantly improved total GRSR(T-GRSP) and easily extracted GRSP(EE-GRSP) concentrations compared to control, besides the T-GRSP in 1-year experiment and the EE-GRSP in 2-year experiment. A significant increase in SOC content was only observed in 7-year AMF reclaimed soils compared to non-AMF reclaimed soils. Soil total N(TN), Olsen phosphorus(P) and available potassium(K) were significantly higher in inoculated soil after 1–7 years of reclamation(except for individual cases), and increased with reclamation time(besides soil Olsen P). The exotic AMF inoculum markedly increased the average soil invertase, catalase, urease and alkaline phosphatase by 23.8%, 21.3%, 18.8% and 8.6%, respectively(P<0.01), compared with the control. Root mycorrhizal colonization was positively correlated with soil parameters(SOC, TN and soil available K) and soil enzyme activities(soil invertase, catalase, urease and alkaline phosphatase) in both AMF and non-AMF reclaimed soils(P<0.05), excluding availableK in non-AMF reclaimed soils. T-GRSP(P<0.01) and EE-GRSP(P<0.05) were significantly correlated with the majority of edaphic factors, except for soil Olsen P. The positive correlation between root mycorrhizal colonization and available K was observed in AMF reclaimed soils, indicating that the AMF reclaimed soil with a high root mycorrhizal colonization could potentially accumulate available K in soils. Our findings concluded that revegetation with exotic AMF inoculum influenced soil nutrient availability and enzyme activities in the semi-arid ecosystem, suggesting that inoculating AMF can be an effective method to improve soil fertility and support restoration of vegetation communities under poor conditions like soil nutrient deficiency and drought.

Effects of soil salinity on rhizosphere soil microbes in transgenic Bt cotton fields

With increased cultivation of transgenic Bacillus thuringiensis （Bt） cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere microbes and Bt protein residues. In 2013 and 2014, investigations were conducted on the rhizosphere microbial biomass, soil enzyme activities and Bt protein contents of the soil under transgenic Bt cotton （variety GK19） and its parental non-transgenic cotton （Simian 3） cultivated at various salinity levels （1.15, 6.00 and 11.46 dS m-1）. Under soil salinity stress, trace amounts of Bt proteins were ob- served in the Bt cotton GK19 rhizosphere soil, although the protein content increased with cotton growth and increased soil salinity levels. The populations of slight halophilic bacteria, phosphate solubilizing bacteria, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria decreased with increased soil salinity in the Bt and non-Bt cotton rhizosphere soil, and the microbial biomass carbon, microbial respiration and soil catalase, urease and alkaline phosphatase activity also decreased. Correlation analyses showed that the increased Bt protein content in the Bt cotton rhizosphere soil may have been caused by the slower decomposition of soil microorganisms, which suggests that salinity was the main factor influencing the relevant activities of the soil microorganisms and indicates that Bt proteins had no clear adverse effects on the soil microorganisms. The results of this study may provide a theoretical basis for risk assessments of genetically modified cotton in saline alkaline soil.

Impacts of Environmental Factors on Degradation of CrylAb Insecticidal Protein in Leaf-Blade Powders of Transgenic Bt Rice

The determination of the environmental fate of Bt insecticidal protein released by Bt rice plants in paddy soils is a key issue in its ecological risk assessment. In this study, the impacts of soil water content, pH, and temperature on the degradation of CrylAb protein expressed in the leaves of Bt rice KMD2 were studied in the laboratory. Three types of paddy soils were used, i.e., blue clayey paddy soil, pale paddy soil on quaternary red soil, and marine-fluvigenic yellow loamy paddy soil. Ground powders of KMD2 leaf blades were mixed with each type of soil, and degradation dynamics of Cry lAb were measured using enzyme-linked immunosorbent assay （ELISA）. The degradation rate of CrylAb was high at the early experimental stage, but slowed down steadily at middle and later stages, which could be described by exponential equations, with the half-life period of degradation determined as 1.8-4.0 d. The soil water content, pH, and temperature could affect the degradation of CrylAb, but the effects of soil pH and temperature were relatively greater. In general, CrylAb degradations were slower under lower soil pH and temperature conditions, especially for marine-fluvigenic yellow loamy paddy soil.

Predicting Grain Yield and Protein Content in Winter Wheat at Different N Supply Levels Using Canopy Reflectance Spectra

用一个裂口阴谋的一个地实验使随机化有三复制的完全的块设计被执行决定在之间的关系光谱索引和小麦谷物产量( GY )，为 GY 比较四个植被索引(力)的表演预言，并且到学习，到估计谷物蛋白质的 VI 的可行性满足( GPC )在里面冬小麦。二典型冬小麦( Triticum aestivum L.)栽培变种 ‘X uzhou 26'(高蛋白质内容)和 ‘H uaimai 18'(低蛋白质内容)被用作著处理和四 N 率，即， 0 ， 120 ， 210 ，和 300 kg N 哈? 1 ，作为次要情节处理。增加的土壤 N 供应显著地增加了 GY 和 GPC (P ≤ 0.05 ) 。为联合的二栽培变种，重要并且正相关在四个力和 GY 之间被发现，当使用绿比率植被索引(GRVI ) 在时，观察的最强壮的关系地中间充满。累积 VI 实质地估计改进产量预测，与正在出发到成熟舞台的最好的间隔。类似的结果在 VI 和谷物蛋白质产量之间被发现。然而，当使用累积 VI 时， GPC 没显示出重要改进。在叶 N 地位和 GPC 之间的强壮的关系(R2 = 0.9144 为‘ X uzhou 26' 和 R2 = 0.8285 为‘ H uaimai 18') 显示华盖系列能被用来预言 GPC。强壮在估计并且观察的 GPC 之间合适(R2 = 0.7939 ) 显示遥感技术在小麦是谷物蛋白质内容和质量的潜在地有用的预言者。

Effect of Pesticides on Certain Soil Biological and Biochemical Indices of a Paddy Soil

A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (Triazophos, Butachlor and Jinggangmycin) on a paddy field soil health under controlled moisture (flooded soil) and temperature (25℃) conditions. The electron transport system (ETS)/dehydrogenase activity displayed a negative correlation with pesticides concentrations, and the activity was affected adversely as the concentration of the pesticides increased. The higher doses of pesticides, 5 and 10 folds field rates, significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect against the control. The relative toxicity level of pesticides in decreasing the ETS activity was in the following order: Triazophos>Jinggangmycin>Butachlor, irrespective of their rates of application. The pesticides caused an improvement in the soil phenol content and it increased with increasing the concentration of agrochemicals. The pesticide incorporation did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of pesticides in the given order of Triazophos>Jinggangmycin>Butachlor; and the toxicity was in the order: 10 FR (times of field rate)>5 FR>1.0 FR>0.5 FR>control.

Novel Inorganic Pyrophosphatase from Soil Metagenomic and Family and Subfamily Prediction

Inorganic pyrophosphatase (PPase) is widely studied, to be extremely important for survival of plants and microorganisms. PPases catalyze an essential reaction the hydrolysis of inorganic pyrophosphate (PPi) to inorganic phosphate (Pi). Studies involving the mechanism of PPase were performed in microorganisms culture. We didn’t found reports of PPase derived from soil meta-genomic libraries. Soil environment has immense diversity of microorganisms, yet most remains unexplored and the metagenome are the technologies used and investigate uncultured microorganisms potential. The aim is to identify novel genes using the metagenomic approaches from a bioinformatics perspective and hopefully will serve as a useful resource. With this purpose, we used the metagenomic library of Eucalyptus spp. arboretum (EAA). We did a screening to select a positive clone and submitted them to the process of shotgun. The data obtained was submitted to bioinformatics analyses. These analyses identified were the novel MetaPPase gene and were classified according to the predict family and subfamily.

Alteration of certain soil microbiological and biochemical indices of a paddy soil under anthropogenic stress

A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (insecticide, herbicide, fungicide) on paddy field soil health under omatrolld moisture (flooded soil) and tem-perature (25℃ ) environment. The electron system (ETS)/Dehydrogenase activity showed negative correlation with pesticides concentrations, decreased with increase of pesticide ooncentration. The higher doses (5 to 10 times field rates) of pesticides significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect on the control. The toxicity of pesticides in decreasing the ETS activity was in the order: insectidde > fungicide > herbicide, irrespective of their rates of application. The pasticides increased the soil phenol content, which increased with increasing concentration of agrochemicals. The pesticide applieatkm did not produce any significant change in soil protein content. The response of biomamess phospholipid content was nearly similar to that of ETS activity. The phospholipid content decreased with the addition of pesficides in the order insecfidde > furgicide > herbicide and the maidty was in the order: 10 FR (field rate) > 5FR> 1.0 FR > 0.5 FR >control.

柳枝稷对滨海盐碱地的改良效果及饲用价值

为探究柳枝稷(Panicum virgatum)在滨海盐碱地改良方面的作用及其饲用价值,本研究在黄河三角洲盐碱地开展了田间试验和家庭农场饲喂试验,研究了柳枝稷不同种植密度和年限对盐碱地的改良效果以及柳枝稷饲喂对鲁波山羊生长性能的影响。结果显示,相较于种植以前,1 m×1 m种植密度的柳枝稷,在种植4年后土壤有机质增加了55%(P=0.09),盐分含量显著降低了59%(P<0.05)。此外,两个种植密度(1 m×1 m和1 m×3 m)的柳枝稷,均能显著降低大多数土壤重金属的含量(P<0.05)。饲喂试验发现,柳枝稷与花生(Arachis hypogaea)秧不同比例混合,均能不同程度地促进鲁波山羊的生长,以柳枝稷꞉花生秧为3꞉7时效果最佳。本研究证明,1 m×1 m种植密度的柳枝稷能够有效改良滨海盐碱土壤,同时兼具一定的饲用价值,对黄河三角洲盐碱地生态草牧业发展具有重要的指导意义。

土壤硒干预与5种作物集硒特性研究

[目的]探究不同施硒浓度对5种作物的影响,了解不同作物的硒吸收及积累特性,为筛选适宜大规模种植的硒蛋白原料提供理论依据。[方法]选用油菜、玉米、洋葱、番茄、绿豆分别代表不同科作物进行盆栽试验,以亚硒酸钠为硒源调控土壤基质中的施硒浓度分别达20、40、60、80 mg/kg,同时以不施硒的基质为对照组(CK),培育作物直至开花期,采收其地上部分并测定其硒含量、蛋白含量及蛋白中的硒含量,结合作物生物学产量计算硒积累量与蛋白中硒积累量,从而分析5种作物对硒的吸收与积累情况,并筛选出适合硒蛋白生产的最佳原料。[结果]玉米、洋葱、绿豆、番茄和油菜最佳施硒浓度分别为60、20、60、40、60 mg/kg。在最佳施硒浓度下玉米、洋葱、绿豆、番茄和油菜的蛋白中硒积累量表现为油菜>玉米>番茄>绿豆>洋葱。[结论]与玉米、洋葱、番茄和绿豆相比,油菜的蛋白含量与蛋白硒含量最高,是潜在优良的硒蛋白来源作物,且在施硒浓度为60 mg/kg时表现出最佳的集硒特性。

放牧强度对短花针茅草原球囊霉素相关土壤蛋白含量的影响

球囊霉素相关土壤蛋白(GRSP)是一种糖蛋白物质,对土壤有机碳固持和维持团聚体稳定性具有重要作用。目前,长期不同放牧强度对荒漠草原GRSP的影响尚不清晰。依托内蒙古短花针茅草原长期不同放牧强度野外实验平台,分析不同放牧强度对短花针茅草原土壤GRSP含量、有机碳含量和团聚体稳定性的影响及其相互关系,结果表明:总球囊霉素相关土壤蛋白(T-GRSP)含量在中度放牧(1.26 mg/g)和重度放牧(1.22 mg/g)下显著低于对照(1.44 mg/g),轻度放牧(1.41 mg/g)与对照无显著差异;易提取球囊霉素相关土壤蛋白(EE-GRSP)含量在重度放牧下显著低于其他处理(P<0.05);冗余分析表明,土壤容重(P=0.004)、硝态氮(P=0.03)和有效磷(P=0.044)是影响GRSP含量的主要因子;EE-GRSP和T-GRSP与土壤团聚体稳定性和土壤有机碳含量之间均存在显著正相关关系(P<0.05)。综合分析表明,轻度放牧更有利于荒漠草原土壤有机碳、团聚体稳定性和GRSP的维持。

玉米间作马铃薯对根际土壤酶活性及团聚体稳定性的影响

[目的]阐明影响水稳性团聚体稳定性的主要因素,为云南省红壤坡耕地综合治理提供科技支撑。[方法]设置玉米单作、马铃薯单作、玉米与马铃薯间作3个处理,分析了间作对作物根际土壤养分含量、酶活性、球囊霉素相关土壤蛋白(GRSP)含量、团聚体组成和稳定性的影响,以及对作物的农艺性状及产量的影响。[结果](1)相比于单作,玉米与马铃薯间作不仅能使马铃薯根际土壤中的有机质、速效磷含量分别显著增加了13.53%,46.53%(p<0.05),而且能使两种作物根际土壤的总球囊霉素相关土壤蛋白(T-GRSP)和易提取球囊霉素相关土壤蛋白(EE-GRSP)含量均有增加趋势,其中玉米的差异性达显著水平(p<0.05)。(2)相比于单作,玉米与马铃薯间作可以显著增加两种作物根际土壤的脲酶、酸性磷酸酶和过氧化氢酶活性,以及>0.25 mm水稳性团聚体含量(R 0.25)和平均质量直径(MWD)值(p<0.05),玉米的增幅为17.63%~41.29%,马铃薯的增幅为10.81%~34.79%。(3)相比于单作,玉米与马铃薯间作均可显著增加两种作物的地上部和根系的干重(p<0.05)。玉米与马铃薯间作时土地当量比为1.81>1,具有间作产量优势。(4)相关性分析得出,EE-GRSP、T-GRSP、脲酶、酸性磷酸酶、过氧化氢酶均与R 0.25,MWD呈显著正相关关系(p<0.05)。冗余分析得出,各指标对团聚体指标的影响由大到小分别为过氧化氢酶>脲酶>EE-GRSP>酸性磷酸酶>T-GRSP,其中,过氧化氢酶是影响土壤团聚体组成和稳定的主要影响因子。[结论]玉米与马铃薯间作不仅能促进两种作物根际土壤的物质循环、增加团聚体的大粒级含量和稳定性,还能促进两种作物地上部和根系生长,这对于云南省红壤坡耕地合理间作作物的选择具有重要意义。

镉(Cd)胁迫下蓖麻蛋白质组学筛查及RcBSK7抗性功能研究

为揭示蓖麻(Ricinus communis)植株响应重金属镉(Cd)胁迫相关机制,筛选出蓖麻中参与Cd胁迫的抗性基因。本研究通过观察种子发芽及植株生长状态,最终确定以水处理的蓖麻植株为对照,研究其在3种剂量(300、700、1000 mg·L^(-1))Cd胁迫处理下的反应机制,以期为揭示蓖麻响应Cd胁迫的防御和解毒机制提供新思路。利用差异蛋白质组学分析蓖麻在Cd胁迫下的网络调控机制,即随着Cd胁迫浓度的增加,蓖麻植株分别通过阻隔根系对重金属Cd的吸收、提高自身抗氧化能力、抑制Cd^(2+)运转以及诱导细胞程序性死亡等防御解毒过程以抵抗Cd胁迫损伤。根据组学分析结果筛选出差异显著基因RcBSK7,通过在拟南芥(Arabidopsis thaliana)中进行功能验证可知,该基因对提高蓖麻对Cd耐受性具有重要的作用。本研究增强了对蓖麻植株在3种Cd胁迫下多样性和复杂性的认识,为耐Cd基因鉴定和土壤中重金属污染修复提供了有价值的理论依据。