植物活体水分探测仪的研制及测试初报

利用NIM插件探测器及金硅面垒探头组装了植物活体水分探测仪;筛选并分析了仪器的最佳工作条件;检测了春小麦、玉米、苜蓿、豌豆、红豆草叶片鲜重的变化。结果表明;叶片水分随时间损失大的,其抗旱性差。叶片保水的秩序为:红豆草、豌豆>苜蓿>春小麦>玉米。     

Effect of Nitrogen Rate and Stubble Height on Dry Matter Yield,Crude Protein Content and Crude Protein Yield of a Sorghum–Sudangrass Hybrid[Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf.] in the Three‐Cutting System

In this study, the effects of nitrogen (N) rate (60, 120, 180 and 240 kg N ha^?1 applied in three equal dressings at seeding and after the first and second cuttings) and stubble height (7, 14 and 21 cm) on the dry matter (DM) yield, crude protein (CP) content, and CP yield of a sorghum–sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf., cv. Pioneer 988] in the three‐cut system was investigated. The N rate had no significant effect in the first and third cuttings, but in the second cutting DM yields increased significantly with increase in N rate. The highest yield of 9.1 t ha^?1 was obtained with 80 kg N ha^?1 for the average of 2 years at the second cutting, but no significant difference was found among the 40, 60 and 80 kg N ha^?1 rates. CP content and yield were not significantly affected by N rate at the first and third cuttings, but CP content and yield were significantly affected by application of N at the second cutting. Stubble height had a significant effect on CP content at the third cutting. However, it had no significant effect on CP content at the first and second cuttings. Stubble height had a significant effect on the CP yield at the first cutting, but no significant effect on CP yield at the second and third cuttings.     

华北落叶松种子贮藏试验浅析

在三种库房里对五种不同含水率、两种包装的华北落叶松种子进行了60个月的贮藏试验。结果认为，含水率5．19／5～8．0％的落叶松种子可以在三种库房密封贮藏39个月。种子贮藏的最佳含水率为6．6％～8．0%，最佳的库房是冷库(0C～5C)。磨口瓶与布袋在冷库贮藏效果差异不明显；地下库不能用布袋贮藏；在普通常温库中磨口瓶比布袋能多贮藏12个～18个月。     

尕海地区弃耕地土壤可溶性盐分测定

１９９０～１９９３年在柴达盆地尕海地区弃耕地进行土壤可溶性盐分测定，测定结果，该地区土壤盐分组成为氯化物－硫酸盐和硫酸盐－氯化物，大部分地区耕层盐分含量小于１０ｇ．ｋｇ＾－１，少部分盐荒地表层含盐量高达７０ｇ．ｋｇ＾－１，牧草生长季节中，土壤盐分含量最低期在６月份。     

Correlation between hydrolytic enzyme activities measured in bean seedlings afterTrichoderma koningii treatment combined with pregermination and the protective effect againstPythium splendens

An experimental protocol consisting in the colonisation of pregerminated bean seeds dressed withTrichoderma sp. was used in order to study the mechanisms correlated with the protective effect againstPythium splendens. Seed dressed with TH-11 (T. koningii) for 24 h presented a higher protective effect and a higher level of seed colonisation as compared to those dressed with TH-13 (T. longibranchiatum). The levels of seed coat colonisation by TH-11 and TH-13 was shown to be correlated with the carboxymethylcellulase activity, as measured in the seed coats retreived from germinating dressed bean seeds. The seed coat colonisation was also associated with an increased activities of endo-1,3--glucanase and endochitinase measured in seed extracts, and an inhibitory effect of seed extracts onPythium sporangia germination. Pretreatment of TH-13-dressed seeds with a commercial cellulase improved all parameters mentioned above, thus suggesting a role of cellulase activity in the colonisation process and the linked protective effect. The possible role of hydrolytic enzymes in the protective effects is discussed.     

加热光纤法同步测定土壤水热参数误差分析

土壤水热参数是研究土壤水热传输的基本物理参数。当前热脉冲探针法（HPP）可同步测定土壤水热参数,但该方法仅限于在点尺度下测定。与其具有相同理论基础的加热光纤法（SPHP-DTS）,可将测定尺度增大至田间千米尺度,但其测定精度尚未得到有效验证。为了探知SPHP-DTS法的误差,本研究进行了SPHP-DTS法与HPP法测定土壤水热参数的对比试验。结果表明,以HPP为标准,加热光纤法测定热导率的精度RMSE为0.13 W?m-1?℃-1。SPHP-DTS法测定的热导率显著高于HPP法,主要原因在于加热光纤时产生的温度效应。通过热导率法测定土壤含水率时,在热导率测定误差的影响下,SPHP-DTS法的测定精度明显低于HPP法。SPHP-DTS法测定土壤水热参数的其他误差来源包括光纤与土壤之间多个界面的接触热阻、光纤的温度敏感性、噪音干扰以及温度梯度驱动下的水分迁移。本研究可为SPHP-DTS法提升土壤水热参数测定精度提供理论参考。     

Influence of the physical and chemical properties of soil on the retention process of isoxaflutole and its two main derivatives

Isoxaflutole is a new pre‐emergence herbicide for use in maize and sugarcane. Its two main derivatives are a diketonitrile derivative, the 2‐cyano‐3‐cyclopropyl‐1‐(2‐methanesulfonyl‐4‐trifluoromethylphenyl)propan‐1,3‐dione, named DKN, and a benzoic acid derivative, the 2‐methanesulfonyl‐4‐trifluoromethylbenzoic acid, named BA. The adsorption/desorption processes have never been studied for isoxaflutole (IFT) at high concentrations nor for BA, and the present work aimed at completing the knowledge of the behaviour of these three molecules in conditions close to those encountered in the context of agricultural use. The adsorption/desorption study was conducted on seven soils of different physical and chemical properties, using the batch equilibrium technique. During the experiments, IFT was chemically converted into DKN in a continuous manner. This reaction appeared to be dependent on the pH of the soil and was taken into account in the calculations of the adsorbed and desorbed amounts. The adsorption isotherms obtained were predominantly C‐shaped for IFT and DKN and S‐shaped for BA, but some differences appeared on a few soils. They fitted well the Freundlich equation, and the values of the Freundlich coefficient K_fa showed that, whatever the soil, IFT was more adsorbed than its two derivatives. The main parameter influencing the adsorption of IFT appeared to be the organic matter content, whereas this effect was not evident for DKN and BA. No correlation was found between the extent of adsorption and either clay content or pH of the soil, for the three molecules.     

稀土对刺槐苗木生理特性影响的研究

稀土对刺槐苗木生理特性影响的研究赵兰勇，梁玉堂（山东农业大学林学院泰安２７１０１８）王九龄（北京林业大学北京１０００８３）关键词稀土，刺槐，光合速率，叶绿素含量，水分利用效率，矿质元素含量近年来，稀土元素在农业上的应用研究越来越受到人们的重视，并且已...