低磷胁迫下熊猫豆侧根增多的生理机制研究

采用溶液培养方法,通过外源添加生长素吲哚-3-乙酸（IAA）及生长素极性运输抑制剂2,3,5-三碘苯甲酸（TIBA）,研究了低磷胁迫下熊猫豆根系构型与生长素相关代谢酶活性之间的关系,以阐明生长素在低磷胁迫下塑造植物根系构型的作用。结果表明,熊猫豆在低磷胁迫下形成特定根系构型,具体表现为侧根增多。IAA在侧根发生过程中起重要作用,外源IAA可以在一定程度上模拟低磷信号引导的侧根发生,而生长素极性运输抑制剂TIBA则显著抑制侧根发生。根系中生长素代谢相关酶生长素氧化酶（IAAO）和过氧化物酶（POD）活性在根构型形成过程中呈现规律性变化。低磷环境下熊猫豆根系中的IAAO、 POD酶活性均高于正常施磷的处理。外源IAA可以增加这两种酶的活性,而TIBA则能够逆转低磷诱导的IAAO、 POD活性的增加。     

衡阳紫色土丘陵坡地不同植被恢复过程中土壤水文效应

采用空间代替时间序列方法, 对衡阳紫色土丘陵坡地不同植被恢复阶段土壤层的水文效应进行研究。结果表明: (1)从裸露地、草坡、灌草、灌丛至乔灌恢复阶段, 土壤蓄水性与渗透性显著增加(P<0.05); (2)Horton入渗模型对各植被恢复阶段的入渗过程拟合效果较好(R²≥0.765), 有较好的适用性; (3)土壤理化性状、植被根系显著影响土壤的渗透性能, 植被根系提高土壤入渗性能的实质是: ≤1 mm细根可有效改善土壤的理化性状; (4)基于主成分分析, 从裸露地、草坡、灌草、灌丛至乔灌恢复阶段, 土壤综合水文效应显著提高(P<0.05)。此研究结果将丰富该地区植物生态学与恢复生态学的内容, 并为衡阳紫色土丘陵坡地生态系统的恢复与重建提供重要依据。     

Analysis of NO3 interception of the parasitic angiosperm Orobanche spp. using a positron-emitting tracer imaging system and 13NO− 3: A new method for the visualization and quantitative analysis of the NO3 interception ratio

Abstract

The root parasitic plants Orobanche spp. (broomrapes) seriously affect agricultural production. A visualization and quantitative analytical method for the interception of nutrients was established using a positron-emitting tracer imaging system and ¹³NO^? ₃. By using this analytical method that involves volume normalization with ¹⁸F^? images, the nitrogen nutrient interception ratio of the Orobanche spp. was calculated to be 73.6 ± 3.9% in a host–parasite system of red clover (Trifolium pratense L.).     

几种城市绿地草坪草需水规律研究

为对城市绿地草坪草进行更合理的种植灌溉,采用小区微灌试验,对剪股颖、马蹄金、早熟禾和白三叶四种具有代表性的绿地草坪草的需水规律进行研究。试验结果表明:（1）供试草坪草根系在土层中的分布呈“伞”形结构,83%～94.4%的根系聚集在0—10 cm的土层中,不耐干旱,需适时补充灌溉,以维持其正常生长;（2）供试草坪草年需水总量在1 000 mm左右,66%的需水量集中在6—9月4个月内。在水资源紧缺的北方城市绿地建设中,不宜大面积配置草坪草;（3）草坪草的灌水周期以5 d,次灌水量33 mm较为适宜。     

Harmful winter wheat diseases and possibilities for their integrated control in Latvia

Decision support systems based on control thresholds are an important part of integrated disease control systems in winter wheat. Various warning and forecast systems have been developed in different countries (in Latvia – under the framework of Danish-Baltic joint project ‘Development and Implementation of an Internet-based Decision Support System for Integrated Pest Management’), but results were contradictory. The aim of this investigation was to identify the possibilities for integrated disease control under intensive management of winter wheat. Different schemes of fungicide treatment, including a decision support system, were tested in field trials from 2008 to 2012 in two places. Leaf blotches caused by Pyrenophora tritici-repentis and Zymoseptoria tritici are recognised as the most harmful wheat diseases in Latvia. The total impact of diseases, which was calculated as area under disease progress curves, was affected by the year and the scheme of fungicide treatment. Significantly higher yields were obtained in treatments with fungicide application, but differences between control strategies were not significant. The obtained results confirmed that two fungicide applications are not necessary (except certain cases). The results suggest that recommendations should be based on the disease incidence on the third or second leaf of wheat.     

基于土地整治的项目区耕地资源社会价值评定及变化分析

社会效益评价是土地整治的重要内容之一, 而整治项目区社会价值是土地整治社会效益评价的重要依据, 因此, 开展项目区耕地资源社会价值评定研究对土地整治社会效益评价具有重要意义。本文以河北省曲阳县土地整治项目为例, 通过构建基于土地整治的项目区社会价值评定体系, 借鉴资源经济学的市场价值法、替代市场法、成果参照法及资本还原法等研究方法, 实现土地整治项目区社会价值货币化, 并对整治前后的价值变化进行分析。结果表明, 研究区在土地整治后, 社会保障价值增加32 442.02万元, 但所占总价值比例较整治前有所降低; 社会稳定价值增加1 453.29万元, 人文景观价值增加884.37万元, 且两者占总价值比例均有所升高。耕地总社会价值增加34 779.68万元, 土地整治社会效益显著, 不仅实现了耕作条件的便利、耕地面积的增加, 更实现了生态景观价值的提高。该研究方法对土地整治社会价值评定有借鉴意义, 评价结果可为曲阳县土地整治社会效益评价提供科学依据。     

图书馆网站评估分析系统设计与实现

采用定量分析的方法,利用计算机技术制作了一个图书馆网站评估分析系统。该系统作为高职院校图书馆网站建设的评估工具,增强了我国图书馆网站建设评估的可操作性。     

县域农业土地利用多目标决策指标体系的研究

针对县域农业土地利用多目标决策规划,构建了产地环境条件子系统、自然条件子系统、经济效益分析子系统和环境影响分析子系统以及各自包含的评价指数集。产地环境条件指标集和自然条件指标集是基于现状的,采用结果指标表达;环境影响分析和经济效益分析是一种预测评价,对其指标集的构建采用了过程指标的设计。由于把相应指数值进行趋同转换,使在适宜性评价和更高层次评价的时候带来了方便,尤其使最小欧氏距离的计算具有直观性。     

Determination of the different components of cadmium short‐term uptake by roots

As the various components of the cadmium (Cd) root sink have not been clearly described, there is a need to precisely measure the respective contributions of apoplast and symplast to short‐term root Cd uptake and to explain the linear component of the absorption isotherms. A new method of fractionating Cd in roots was applied to two plant species with contrasting abilities to accumulate Cd: maize (Zea mays) and a Cd‐hyperaccumulating ecotype of alpine pennycress (Noccaea caerulescens). Their roots were exposed for 1 h to increasing concentrations of labeled Cd. Series of desorption baths were used to obtain the root apoplastic Cd in combination with a brief freezing step in liquid nitrogen to separate the intracellular metal from the apoplastic one. The apoplastic uptake accounted for 15% to 82% and for 48% to 96% of the total Cd uptake of maize and of alpine pennycress roots, respectively. In the case of maize, the concentration‐dependent symplastic net flux fitted a biphasic Michaelis‐Menten function, while in the case of alpine pennycress, a Michaelis‐Menten‐plus‐linear function proved a better fit. The second component of the symplastic net flux may reflect absorption through a low‐affinity transport system. Short‐term Cd uptake by roots is dominated by the high‐affinity transport system for exposure concentrations below 1 μM for maize and 0.2 μM for alpine pennycress, while cell‐wall binding prevailed for higher exposure concentrations.     

半干旱地区不同年代冬小麦品种根系生长和水分利用效率对种植密度的响应

优良的品种与科学合理的种植密度是提高小麦产量的基础。试验以3个不同年代在黄土高原半干旱地区大面积推广的冬小麦品种为试验材料,设置了3个种植密度（100万株/hm²、250万株/hm²、350万株/hm²）,通过田间小区实验研究了种植密度对其根系生长,产量及其水分利用效率的影响。结果表明:不同年代冬小麦品种的根系生长,水分利用效率及其产量对种植密度的响应不同。1960s品种（丰产3号）的根系生长、产量及水分利用效率随种植密度的增加而降低;1980s品种（小偃6号）在中密度时根系生长,产量及水分利用效率最大,低密度次之,高密度最小;现代品种（长旱58）根系生长,产量及水分利用效率随种植密度的增加而提高。在本实验条件下,现代品种较前品种的最高水分利用效率和最高产量均显著增加,而相应的根重密度和根长密度却显著降低。这表明在黄土高原半干旱地区小麦品种更替过程中,小麦的根系生长可能存在对其产量和水分利用效率不利的冗余,只不过这种根系生长的冗余随品种的更替而降低,并因此提高了其水分利用效率和产量。