Simulating site-specific impacts of climate change on soil erosion and surface hydrology in southern Loess Plateau of China

Proper spatial and temporal treatments of climate change scenarios projected by General Circulation Models (GCMs) are critical to accurate assessment of climatic impacts on natural resources and ecosystems. The objective of this study was to evaluate the site-specific impacts of climate change on soil erosion and surface hydrology at the Changwu station of Shaanxi, China using a new spatiotemporal downscaling method. The Water Erosion Prediction Project (WEPP) model and climate change scenarios projected by the U.K. Hadley Centre's GCM (HadCM3) under the A2, B2, and GGa emissions scenarios were used in this study. The monthly precipitation and temperature projections were downloaded for the periods of 1900–1999 and 2010–2039 for the grid box containing the Changwu station. Univariate transfer functions were derived by matching probability distributions between station-measured and GCM-projected monthly precipitation and temperature for the 1950–1999 period. The derived functions were used to spatially downscale the GCM monthly projections of 2010–2039 in the grid box to the Changwu station. The downscaled monthly data were further disaggregated to daily weather series using a stochastic weather generator (CLIGEN). The HadCM3 projected that average annual precipitation during 2010–2039 would increase by 4 to 18% at Changwu and that frequency and intensity of large storms would also increase. Under the conventional tillage, simulated percent increases during 2010–2039, compared with the present climate, would be 49–112% for runoff and 31–167% for soil loss. However, simulated soil losses under the conservation tillage during 2010–2039 would be reduced by 39–51% compared with those under the conventional tillage in the present climate. The considerable reduction in soil loss in the conservation tillage indicates the importance of adopting conservation tillage in the region to control soil erosion under climate change.     

梨感染茎痘病毒后过氧化物酶活性及其同工酶的变化研究

当年生早酥梨幼苗接种茎痘病毒（SPV）后．从第4天开始测定其叶片的过氧化物酶及其同工酶。结果表明．梨感染SPV后过氧化物酶活性显著高于健康无毒植株．其增酶高峰期在7天左右；过氧化物酶的同工酶也发生明显的变化．接种SPV后．有些弱带比无毒健株提早出现。     

配电系统可靠性数据统计与分析

本文以某市配电系统为主要研究对象，通过与国内外配电系统可靠性数据的对比，找出该配电系统在网络结构，设备可靠性及运行管理方面的不足，提出提高其可靠性的技术与管理措施。     

Root carbohydrate reserves, mineral nutrient concentrations and biomass in a healthy and a declining sugar maple (Acer saccharum) stand

Soil and root characteristics were contrasted between a "declining" and a "healthy" sugar maple (Acer saccharum Marsh.) stand in Vermont, USA. The declining stand had lower basal area increment and more crown dieback than the healthy stand. Soil pH and base cation content were lower and soil water content was higher at the site of the declining stand than at the site of the healthy stand, whereas soil temperature did not differ significantly between the sites. In live fine roots, concentrations of K and Ca were marginally (P < 0.07) lower in the declining than in the healthy stand, whereas concentrations of N, P, Mg, and Al were not significantly different (P = 0.13 to 0.87) between stands. Starch and soluble sugar concentrations of fine and coarse roots did not differ significantly between stands, indicating that crown dieback did not affect carbohydrate supply to the roots in the declining stand. Throughout the growing season, the standing live and dead root biomass were significantly higher in the declining stand than in the healthy stand, indicating that more carbon was allocated to roots and that root turnover was higher in the declining stand than in the healthy stand.     

压缩秸秆物理特征分析研究

分析了生物质秸秆资源的国内利用现状,通过检测得出了实验结论：秸秆压块的含水率4．74％,比重o．86×10^-6m^3／g,热值19．49kJ／g与原煤热值相近。并探讨了秸秆代替原煤当作新能源综合利用的可行性,指出了农作物桔杆综合利用是农业发展循环经济的一个重要方面,是实现全面、协调、可持续发展、建设社会主义新农村的具体要求。     

黄金茶CsDAM2基因克隆及其功能分析

休眠是通过植物体内相应基因的表达调控机制,使植物芽停止生长,以适应外界低温、短日照等不良环境条件的结果。茶芽打破休眠的早晚,密切关系到茶树经济生产的效益。为进一步掌握茶树芽休眠与解除的分子机理>本研究克隆了可能与黄金茶发芽早相关的转录因子(dormancy associated MADS-box CsDAM2),并在烟草中过表达CsDAM2,对CsDAM2转基因烟草和野生型烟草进行低温处理。结果表明,在相同处理条件下,随着温度的降低,同野生型烟草比较,转基因烟草电导率增加幅度小,并且叶绿素荧光值降低率低,说明在抗寒性能上,转基因烟草具有显著优势,进而一定程度上证实了 CsDAM2具有提髙茶树抗寒性的作用。本研究结果为进一步揭示茶树芽休眠与解除的分子机理提供了科学依据。     

Potassium fertilization improves apple fruit (Malus domestica Borkh. Cv. Fuji) development by regulating trehalose metabolism

Potassium (K) fertilization and antioxidant enzymes both positively influence plant growth and development. However, it is not known whether K treatment improves fruit development via increasing soluble sugar. In this study, K-treated apple (Malus domestica Borkh.) fruit was harvested from 60 to 150 days after full bloom and was analyzed for ROS production and trehalose metabolism. The results show that K fertilization improved fruit firmness, increased growth according to several parameters, increased soluble sugar content, and decreased ROS production. The ascorbate metabolic pathway more effectively reduced ROS production than catalase and peroxidase (POD) did under K treatment. Trehalose-treated fruit also showed higher activity of ascorbate-related enzymes (DHAR, GR, and APX) compared with non-treated fruit. The changes of antioxidant enzyme activity in trehalose-treated fruit corresponded to those in K-treated fruit. Moreover, trehalase (TREH) activity in fruit was notably reduced by K treatment. This demonstrates that K influences ROS production via regulating trehalose content and TREH activity in fruit. This study provides new insight into the K mechanism which improves fruit development, including fruit firmness and size.     

几个杂交稻组合的适应性分析

以汕优63为对照,通过比较Ⅱ优084、Ⅱ优838、Ⅱ优725、粤优938、两优培九和丰优香占等6个组合对水稻主要病害的抗性、秧龄弹性以及对高温和涝害适应的能力,研究结果表明:6个组合中Ⅱ优084适应性最好,总体上强于汕优63;其次为Ⅱ优838和Ⅱ优725,总体上与汕优63相当;粤优938、两优培九和丰优香占的适应性总体上不如汕优63。     

云南引进帝国百脉根的研究

对引进帝国百脉根进行茎叶比、干鲜比、干草产量、营养成分和体外干物质消化率(IVDMD)的测定。结果表明，帝国百脉根含有丰富的营养，分枝期和盛花期粗蛋白含量分别高达28．0%和20．79%，粗纤维含量为13．0%和17．46%，Ca、P 丰富，比例恰当，体外干物质消化率较高而稳定，在分枝期和开花期分别为58．64%和57．25%。因此，帝国百脉根为饲用价值较高的优良豆科牧草，应予以进一步开发利用。     

生物能源植物小桐子功能基因及基因组研究进展

为缓解能源需求与原油价格不断上涨以及有限的化石燃料储备之间的矛盾,人们得寻找更加生态、可持续再生的替代能源。利用能源植物生产生物柴油与生物酒精类燃料已成为发展的方向。其中,大戟科的小桐子以其强抗逆性、高含油量等特点而受到了广泛的关注。本文综述了能源植物小桐子油脂含量与质量、生物代谢以及抗逆性等方面的相关功能基因、细胞学染色体核型、核基因组以及叶绿体基因组的研究进展,以期为能源植物小桐子的遗传改良提供参考。