Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.     

黄淮平原节水高效灌溉技术综合评价分析

以黄淮平原种植区为研究对象,综合种植区的自然地理、生态环境和农业发展状况等因素,借助层次分析和模糊数学方法,建立了黄淮平原灌水技术选择模型。利用单因素、多因素法提出了节水灌溉技术选择的方法,优选出最适宜灌溉技术。在喷灌、滴灌、微喷灌、低压管灌和畦灌5种方案中,运用所建立模型选择最优的灌水技术,综合因子大小为微喷灌>喷灌>低压管灌>滴灌>畦灌。黄淮平原种植区适宜灌溉技术为微喷带灌溉技术。     

不同自燃性煤氧化阶段的表征差异

对3种不同自燃倾向性煤样进行低温氧化实验,利用CO体积分数与煤体温度间变化的计算模型,求解出活化能和煤氧化过程发生转变的特征温度,同时结合热重-差示扫描量热（TG-DSC,theremogravimetric analysis-differential scanning calorimetry）实验结果,分析了不同自燃性煤氧化特性和活化能的低温表征规律。结果表明：1）低温氧化阶段,CO生成量、耗氧量和耗氧速率随着煤自燃倾向性增强而增大;不同煤样在实验过程中出现同样的CO生成量和耗氧速率急剧上升的温度拐点,且煤的自燃性越强,该拐点温度越低,同时CO体积分数的变化具有明显的阶段性。2）不同自燃性煤氧化阶段活化能变化规律存在显著差异,当各煤样的温度到达活性温度时,活化能快速减少,且活化能变化点对应于煤氧化过程发生转变的特征温度点。3）根据煤特征温度和活化能的变化规律,把煤低温氧化进程分为4个阶段,分别为表面氧化、氧化自热、加速氧化和深度氧化。     

基于突变级数模型乡镇土地利用总体规划方案决策——以梨林镇为例

乡镇土地利用总体规划作为最基础、最具体的规划,如何科学、有效地协调各方利益优选规划方案已成为乡镇土地利用规划编制与实施的重要课题。以济源市梨林镇为例,从经济、社会和环境等方面构建乡镇土地利用总体规划方案决策评价指标体系,采用突变级数模型对梨林镇土地利用总体规划供选方案进行评价决策。研究表明:基于突变级数模型的评价方法实现定性分析与定量分析的有机结合,反映供选方案之间的细微差别,从而减少主观性又不失科学性,对规划方案的优劣做出正确、有效的评价,并且有效保证多指标的信息量在评价过程中不被丢失,是一种有效的乡镇土地利用总体规划方案决策评价方法。     

Biocontrol of rice blast by the phenaminomethylacetic acid producer of Bacillus methylotrophicus strain BC79

Strain BC79, isolated from primeval forest soil in Qinling, Mountains, China, was identified as Bacillus methylotrophicus based on morphological, biochemical, physiological and chemotaxonomic analyses as well as phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi in dual cultures on solid media. For exploring potential biocontrol activity, we assessed fermentation conditions for studying B. meth1ylotrophicus BC79. The active substance of BC79, phenaminomethylacetic acid, was extracted by TLC and HPLC, and identified as the strongest inhibitory substance described in B. methylotrophicus. Experiments in a greenhouse showed that application of BC79 culture filtrates 24 h before inoculation of Magnaporthe oryzae, the causal agent of rice blast, had 89.87% biocontrol efficiency. B. methylotrophicus BC79 colonized rice plant tissues and at 10 days after filtrate application, its population in leaves (1.65 × 10⁸ CFU/g) was much larger than in stems (6.78 × 10⁷ CFU/g) or roots (3.56 × 10⁷ CFU/g). Field trials indicated that BC79 culture filtrate (4000 g/667 m²) showed the highest efficiency for M. oryzae, with 84.8% biocontrol effect, followed by of 15% phenaminomethylacetic acid extract (75.5%) and 20% tricyclazole (76.1%). Seedling and post-transplant stages were the best periods to apply BC79 for control of rice blast. The B. methylotrophicus BC79 strain hence has enormous potential as an agricultural agent for biocontrol of rice blast.     

Ethylene production by gynoecium and receptacle is associated with sepal abscission in cut Delphinium flowers

Delphinium flowers are sensitive to ethylene, and exposure to ethylene is known to accelerate sepal abscission. The relationship of ethylene to sepal abscission in cut Delphinium flowers was investigated. The gynoecium and receptacle each contributed to climacteric-like increases in ethylene production whereas the sepals, petals and stamens did not. 1-Aminocyclopropane-1-carboxylic acid (ACC) concentration, ACC synthase and ACC oxidase activities in the gynoecium and receptacle increased in the senescing flowers. Wounding of the gynoecium or receptacle accelerated abscission of sepals, which was accompanied by a marked increase in ethylene production. Accelerated sepal abscission was counteracted by treatment with silver thiosulphate complex (STS), an inhibitor of ethylene action. The results of this study show that ethylene produced by the gynoecium and receptacle is closely associated with sepal abscission in cut Delphinium flowers.     

基于高光谱遥感和集成学习方法的冬小麦产量估测研究

【目的】利用2种灌溉处理下不同发育阶段的冬小麦冠层高光谱信息,通过机器学习方法对小麦籽粒产量进行估测精度研究,明确产量最佳估测模型,对于育种工作有着重要应用价值。【方法】以黄淮麦区207个主栽小麦品种为材料,于2018—2019和2019—2020年度连续2个生长季在河南省新乡基地的正常灌溉和节水处理下种植,并调查开花期、灌浆前期和灌浆中期的冠层高光谱数据,分别以6种机器学习方法和集成方法建立光谱指数产量估测模型。【结果】2种灌溉处理下,3个生育期各光谱指数均与产量呈极显著相关（P<0.0001）,且表现出较高的遗传力（0.61-0.85）,主要受遗传因素控制。在正常灌溉处理下,与传统机器学习方法表现最佳的模型相比,集成学习方法在3个生育期的平均决定系数(R²) 分别由0.610、0.611和0.640提高至0.649、0.612和0.675,平均均方根误差 (RMSE) 分别降低至0.607、0.612和0.593 t·hm^-2;节水处理下,3个生育期的平均R²分别由0.461、0.408和0.452提高至0.467、0.433和0.498,平均RMSE分别降低至0.519、0.559和0.504 t·hm^-2。【结论】利用集成方法将不同模型估测结果进行结合,能够有效地提高产量估测精度,2种灌溉处理下均在灌浆中期估测精度最佳,可为冬小麦育种工作中产量估测提供参考。     

Use of Chaetomium globosum for biocontrol of potato late blight disease

The efficacy of Chaetomium globosum as a biocontrol agent against the late blight pathogen Phytophthora infestans was evaluated in potato plants. Among eight Chaetomium isolates evaluated C. globosum isolate Cg-6 showed greater inhibition to mycelial growth of P. infestans in vitro. TLC studies showed that isolate Cg-6 produced an antibiotic called ‘Chaetomin’. Isolate Cg-6 showed greater exo- and endo-glucanase enzyme activity when compared to other isolates. PCR amplification of the ITS region and sequencing of the PCR product confirmed that isolate Cg-6 belongs to the C. globosum group. C. globosum Cg-6 was formulated as a liquid and applied as a tuber, soil and foliar treatment either individually or in combination against Phytophthora infection in potato plants. Among different treatments, combined application of C. globosum as a tuber treatment @ 1 ml/kg of tubers, as a soil application @ 1 ml/kg of Farm Yard Manure (FYM) and foliar spray @ 0.7% resulted in significantly less late blight infection (72%) compared to untreated control (100%) under field conditions. The application of C. globosum resulted in greater tuber yield by reducing late blight infection in two field trials when compared to untreated controls. The study clearly demonstrated the potential use of C. globosum as a biocontrol agent in the management of late blight disease in potato plants.     

基于ITS2序列的12种苔藓植物亲缘关系分析

以尖叶薄鳞苔为外类群,利用ClustalX 2.0和MEGA 4.1软件对12种苔藓植物的ITS2序列进行比对和分析,构建分子系统树.结果表明,12种苔藓植物的ITS2序列长度在432-493bp之间,排序后总长度为540 bp,其中变异位点305个,信息位点200个.12种苔藓植物的遗传距离在0.016～0.472之间,平均遗传距离为0.309.利用MP法建立的系统树显示,12种苔藓植物分为3组,其中7个丛藓科物种聚为一组,3个青藓科物种聚为一组,2种灰藓科植物聚为一组,序列分析结果与形态学分类结果一致,表明ITS2可用于苔藓植物的亲缘关系分析.