白盆珠水库库区坡面径流侵蚀规律初步研究

在对白盆珠水库库区开展水土流失实地调查的基础上,选择库区典型的侵蚀地貌类型与植被类型进行降雨-径流-产沙规律的初步研究.通过6个径流小区试验对比,分析了在不同植被条件下产流、产沙的差异,结果表明缺乏地表草本植被的纯飞播造林的水土保持效益十分有限;库区降雨径流产沙是白盆珠水库淤积的重要来源.     

等高固氮植物篱中套种桑树的桑叶产量及生物产量

对套种在等高固氮植物篱中的桑树（植物篱桑）和地埂桑全年的桑叶产量和生物产量、树势、桑叶营养成分等进行了研究,结果表明,植物篱桑各季的桑叶产量和单叶面积分别比地埂桑高114．3％－180．6％、7．8％－56．6％;全年株总片叶量、株冬条重、株枝叶总量分别比地埂桑高157．0％、294．3％、186．6％;单叶重除晚秋桑比地埂桑高4．1％外,其它各季高27．6％－66．5％;植物篱桑的树势极显著优于地埂桑,其有效条数、平均有效条长、平均粗和平均每m条着叶的数分别比地埂桑高84．8％、29．5％、39．0％、15．5％;植物篱桑下的土壤有机质和全氮含量高于地埂桑;二者桑叶的营养成分高低则相差不大。表5参16。     

Ethylenediurea (EDU): a research tool for assessment and verification of the effects of ground level ozone on plants under natural conditions

Ethylenediurea (EDU) has been widely used to prevent ozone (O₃) injury and crop losses in crop plants and growth reductions in forest trees. Successful use requires establishing a dose/response curve for EDU and the proposed plant in the absence of O₃ and in the presence of O₃ before initiating multiple applications to prevent O₃ injury. EDU can be used to verify foliar O₃ symptoms in the field, and to screen plants for sensitivity to O₃ under ambient conditions. Despite considerable research, the mode of action of EDU remains elusive. Additional research on the mode of action of EDU in suppressing O₃ injury in plants may also be helpful in understanding the mode of action of O₃ in causing injury in plants.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans emissions from open burning of crop residues in China between 1997 and 2004

Annual emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from open burning of crop residues in each province of China mainland between 1997 and 2004 were estimated to be ranged from 1.38x10(3) to 1.52x10(3) g I-TEQ/yr, with the average of 1.50+/-0.08x10(3) g I-TEQ/yr, which contributed to approximately 10% approximately 20% of the total emissions in China. The PCDD/F emissions mainly occurred in the largest crop-producing provinces, especially in those of higher economic levels. The major sources of PCDD/F emissions from open burning in China were found to be cereal residues (i.e. rice, wheat, and corn), which accounted about 70% of the total emissions. Moreover, the first-order one-variable grey differential equation model (GM (1,1) model) for annual emissions of PCDD/Fs was established based on grey system theory. The GM (1,1) model was proved to be robust to predict the annual PCDD/F emissions from crop residue field burning in forthcoming years.     

深耘断根对旱地小麦花后根系衰老及产量的影响

在旱地大田条件下研究了深耘断根对旱地高产小麦花后根系衰老及产量的影响。结果表明,４个处理中以冬前深耘断根最好,起身期深耘断根与对照（不断根）次之,冬前和起身期都深耘断根的效果最差。冬前深耘断根可延迟花后根系活力、根系ＳＯＤ与ＣＡＴ活性、根系可溶性蛋白质含量下降及根系ＭＤＡ含量的升高,从而延迟根系衰老。同时,冬前深耕提高了成穗数及成穗率,使产量提高,因而在旱地高产麦田应提倡冬前深耘断根。图５表１参１     

成都市某区暴雨径流过程模拟分析

为提高城市雨洪管理的效率,最大限度地减少暴雨洪水带来的危害,针对城市防洪排涝的需要,在分析成都市某区降雨径流规律后,建立了该区暴雨径流模拟的数学模型,有助于采取相应措施充分利用雨洪资源。通过对雨洪过程模拟验证表明,模型适合该区域的实际情况,具有一定的合理性和可靠性。     

Influence of furfural concentration on growth and ethanol yield of Saccharomyces kluyveri

Furfural is an important inhibitor in ethanol fermentation process using lignocellulosic hydrolysates as raw materials.In order to find out the fuffural concentration range in which furfural inhibits the fermentation process,we used one strain Saccharomyces kluyveri selected from soil and cultured in several different furfural content media under low glucose concentration condition.Experiment results showed that microorganism growth was stimulated and dry cell weight decreased when furfural concentration in the medium was 0.25 mg/ml.Furfural had negative effect on cell growth when its concentration was above 1.00 mg/ml.At the same time,the strain growed better and had a higher glucose consumption rate in 5% original glucose concentration condition than in 3% original glucose concentration condition.The results showed that appropriate exaltation of original glucose concentration in stalk hydrolysates will increase the strain resistance to furfural.     

华北地区粮食生产与水供应情势分析

华北地区是我国重要的粮食生产基地,其粮食产量在全国粮食总产中的比重由1949年的22%上升到1998年的29.6%。灌溉是保证该区粮食高产稳产的重要保证。华北地区目前用水处于严重紧张状态,1997年人均综合用水量为315m3,农业是用水大户,工农业用水比为1∶5,水资源供需的主要矛盾在农业。华北地区水资源利用率高达98.5%,整体供水潜力所剩无几;随着工业和城镇的发展,农业用水分额将继续减少;同时,受频繁的旱涝灾害、日益严重的水污染和大面积的地下水位下降的影响,农业供水保证率将进一步降低。分析指出,若无连续丰水年和外调水源的补给,要继续保证或发展本区的粮食生产规模,本区的农业用水情势有恶化之势,急需研究并制定出解决本区粮食生产和水资源供给不足矛盾的办法。     

作物间套作群体光能截获和利用机理研究进展

合理的间套作种植模式具有高产高效及环境友好的特点,可能成为未来可持续农业的重要组成部分.光能的高效利用是间套作群体产量占优的主要原因之一.论文综述了计算间套作群体光能截获及分配的半经验模型及理论模型,分析了间套作群体产量优势形成的生理生态基础.间作套种可形成有利于作物吸收光能的冠层结构,或者可促进作物的光合速率,或者可改变作物的收获指数.对于共生期较长的间套作群体而言,优势作物对光能的高效截获和劣势作物对光能的高效利用是群体产量优势形成的主要原因,而对于共生期较短的间套作群体而言,两种作物光能吸收量的增加是该群体高产的主要驱动力.     

采用保护性耕作对减少水稻产量损失的实证分析——基于4省1080个稻农的调研数据

干旱和洪涝是造成水稻减产最主要的自然灾害,稻农通过采用保护性耕作可以减少其对水稻的产量损失。基于2013—2015年中国水稻主产区1 080个水稻农户的调研面板数据,论文采用内生转换模型,实证分析了稻农通过采用保护性耕作应对干旱或洪涝的效果,并分别估计了采用者和未采用者的水稻单产情况。实证结果表明:1)采用者的水稻单产远远高于未采用者的水稻单产;2)在反事实假设情况下,如果采用者未采用保护性耕作,其水稻产量将相应减产457.95 kg/hm~2(约7%);如果未采用者采用保护性耕作,其水稻产量将相应增产225 kg/hm~2(约4%);3)户主种植经验、受教育年限和公共服务可得性正向影响稻农的采用行为。最后,论文建议政府应大力推广保护性耕作技术,加大对抗逆水稻品种的培育,加强对农业生产资料的投入和管理,扩大公共服务的覆盖范围。