退化草地土壤生化活性研究

通过对三种不同退化程度的退化草地土壤生化活性进行测定和相关性分析，结果表明草地退化后其土壤生化活性受到不同程度的影响，表现为土壤生化活性随着退化程度增高而减小，但差异并非都达到统计学上的显著性，而土壤生化活性间的相关性则显著地与草地退化程度有关，说明退化草地土壤微生物间的协调作用受到显著影响，从而影响土壤氮素和碳素代谢途径。     

Correlated Response to Selection for Protein Yield in Oats After Three Cycles of Recurrent Selection

Three oat (Avena saliva L.) populations (i.e., lines of descent), high grain yield (HG), high protein content (HP), and high protein yield per se (HGP), each developed by three cycles of S, recurrent selection, were evaluated for the effect of selection for groat-protein yield upon other agronomic traits. Selections making up the HG line of descent had high protein yield primarily due to high grain yield, and those selected for HP had high protein yield due to both high protein content and high grain yield. Selection in HGP was on the basis of protein yield per se. Selection caused increases in bundle weight, harvest index, vegetative growth rate, and seed number in all lines of descent. Heading date, plant height, and seed weight were unaffected, whereas groat percentage and test weight were decreased in HP and HGP. Heritabilities were high for heading date, plant height, test weight, and seed weight, moderate for harvest index and bundle weight, and low for groat percentage. Genetic variability generally declined from CO to C3 for all traits. Groat-protein yield and amount of protein per groat increased in all lines of descent. In HG, the increase in groat weight was due primarily to increases in the nonprotein fraction, with groat-protein content actually decreasing. In HGP, groat weight increased due to increases in protein and nonprotein fractions, and groat protein content remained constant. In HP, groat weight and amount of nonprotein per groat decreased, thus increasing groat-protein content. Three cycles of recurrent selection resulted in oat lines with groat-protein yields significantly higher than the highest lines from CO. Utilization of index selection may be desirable to obtain populations of greater breeding value.     

巨桉纸浆原料林土壤养分与林木生长研究

通过相关分析及回归分析，探讨了巨桉人工林土壤养分与林木生长的关系，结果表明：土壤速效N、速效P、土壤有机质的浓度与林木胸径、树高、材积极显著正相关，土壤全N、全P与林木胸径树高、材积显著正相关。建立了胸径、树高、材积与土壤养分的线形回归方程，最佳数学表达式说明速效N、速效P是影响巨桉林生长的关键土壤养分。     

洋葱型大蒜及其成因分析

洋葱型大蒜为大蒜鳞茎异常生理变态所形成的类似洋葱鳞茎结构的大蒜(原称“面包蒜”),该鳞茎主要由肥厚的叶鞘基部及鳞芽的外层鳞片加厚所构成,无肉质鳞片或肉质鳞片极不发达,可形成蒜薹或无薹分化,无任何食用价值。洋葱型大蒜的形成与N、P、K超量施用且配比不当,追N过多且时间过早,土壤过于粘重并长期处于水分饱和状态等有密切关系。     

灌丛草地放牧山羊的牧草适口性与嗜食性及山羊采食率研究

通过对放牧山羊的牧草适口性，嗜食性和采食率及其相互关系的分析，表明山羊放牧对灌丛草地的植物适口性、嗜食性比率和采食率均以灌木嫩枝叶，中禾草和苔草属植物较优。季节性规律为：春季山羊喜哺食灌木嫩枝叶，灌木嗜食性比率较高，采食率也较高，夏季山羊喜草本植物，草本植物的嗜食性比率高于灌木，秋季山羊较喜啃食灌木枝叶，嗜食性比率灌木高于草本植物，采食率低于春季，灌木采食率高于草本植物。     

贮藏中福桔果皮细胞结构的显微观察及果实理化成分测定

贮藏期间福桔果皮细胞始终具有分裂增殖能力,细胞生长的养分主要通过维管束向果肉吸取,因而促进果肉衰老,形成枯水.枯水果实在贮藏早期就发现果皮细胞层和油腔分泌细胞无丝分裂旺盛,双核细胞多,果皮增厚多.严重枯水时,果皮细胞还具细胞核、线粒体、有色体等超微结构,未枯水果实细胞分裂少见.经预贮后贮藏的果实,由于中断了果皮组织与维管束的联系,果皮细胞生长受抑制,果肉水分、养分消耗少,枯水率最低,     

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。     

5个草地型草地牧草的生长速率和养分动态研究

在牧草生长季节(5~9月)对小哨牧场放牧演替形成的5个草地型草地的牧草进行生长速率、牧草产量及养分的逐月观测,生长速率测定显示,白三叶+东非狼尾草和东非狼尾草+非洲狗尾草两个草地型草地均出现两个生长峰值,分别在6月和9月,其余3个草地型草地只有一个生长高峰。干物质产量和牧草养分测定结果表明,白三叶+东非狼尾草和白三叶+非洲狗尾草+画眉草两种草地型草地表现最好,可以在气候环境条件类似的地区推广种植利用;白三叶+画眉草和白三叶+非洲狗尾草两种草地型草地表现优良,可以在草地改良中,根据当地实际情况选择性地加以种植;东非狼尾草+非洲狗尾草型草地表现较差,不提倡种植。     

草地土壤肥力及其营养管理的必要性

介绍了草地土壤肥力的来源,土壤基本养分对草地生产的作用,草地植物与动物对养分的需求量及缺乏症状,说明了加强草地营养管理以及维持草地生态系统营养平衡的重要性,指出增强对土壤肥力和营养管理是提高草地生产能力、保证草地生态系统平衡、保障草地可持续利用的关键技术措施。     

Stereoselective degradation of ethofumesate in turfgrass and soil

The stereoselective degradation of ethofumesate in turfgrasses and several agricultural soils was investigated to provide details of the fate of this chiral herbicide. Racemic ethofumesate was either foliar applied to two species of turfgrass or fortified into four types of agricultural soils. (+)- and (−)-Enantiomers were extracted and analyzed by a validated chiral HPLC method which involved extraction of samples with organic solvent followed by separation on cellulose-Tris-(3,5-dimethylphenylcarbamate)-based chiral column and quantification by UV absorbance at 230 nm. Mean recoveries of each enantiomer fortified at 0.5, 5, and 10 μg g⁻¹ ranged from 82.3 ± 5.84 to 92.5 ± 2.87% in turfgrasses and from 86.0 ± 5.09 to 98.1 ± 2.51% in soil. As a measure of this composition, the enantiomeric ratio (ER) was used, defined as the concentration ratio of (+)/(−)-enantiomer. Similarly, preferential degradation of the (−)-enantiomer was observed in both grass species with the largest ER of about 3 and in one of the test soil with ER = 1.65, resulting in residues enriched with (+)-enantiomer. This stereoselective degradation in this soil led to significant difference on half-lives between the two enantiomers. No stereoselective degradation was observed in other soils.