黄土高原沟壑区林地土壤水分特征的研究（I）——土壤水分的垂直变化和季节变化特征

对黄土高原沟壑区南缘的油松(Pinus tabulaeformis)、刺槐(Robinia psedudoacacia)人工林及荒坡的土壤水分动态的研究分析，认为林地土壤水分的垂直变化可以分为：土壤水分微弱利用层、土壤水分利用层、土壤水分调节层和土壤水分微弱调节层，荒坡土壤水分的垂直变化可分为：速变层、活跃层、次活跃层和相对稳定层。各立地土壤水分的季节变化可以分为：土壤水分积累期、土壤水分消退期、土壤水分恢复期、土壤水分稳定期和土壤水分消耗期。     

斜纹夜蛾种群空间动态

利用频次分布法和分布型指数研究了斜纹夜蛾低中龄幼虫在菜芯Ｂｒａｓｓｉｃａ ｐａｒａｃｈｉｎｅｎｓｉｓ Ｂａｉｌｅｙ地内和种群空间分布图式,并研究了各龄幼虫在菜株上的垂直分布。结果表明：斜纹夜蛾 龄幼虫在菜株上呈聚集颁上,频次分布拟事的结果大部分样本符合负二项分布,半产本符合奈曼分布,而不符合泊松分布,频次分布拟事的结果大部样本符合负二项分布,半数样本符合奈曼分布,而不符合泊松分布,幼虫在菜株上的分     

Frequencies of Vertical Resistances and Virulences in the Rye-Powdery Mildew Pathosystem*

Nine populations of rye (Secale cereale L.; the cultivars ‘Kustro’, ‘Danko’ and ‘Carokurz’. a breeding population PA 14/75 and five Iranian primitive ryes) were tested with three or two pathotypes of powder)’ mildew (Erysiphe graminis DC. f. sp. secalis Marchal) to determine the frequencies of vertical resistances. Similarly, three populations of powder)’ mildew isolated from the above eultivars were tested with two rye pathodemes to estimate the frequencies of vertical virulences. Tests were carried out on leaf segments cultivated in vitro. To explain the pattern of the host-parasite interaction, a model with at least four resistance and virulence genes was required. In the rye populations the genotypes of most plants could be determined unambiguously whereas in the powdery mildew populations no unique classification of one-postule isolates was possible due to the limited number of rye differentials. Both the host and the pathogen populations were polymorphic for resistance and virulence, respectively. In all lye populations except PA 14/75 the resistance frequencies were low. In the mildew populations the virulence frequencies were high and complex races occurred rather frequently. The virulence frequencies were related to the resistance frequencies of the respective host population. Results were compared with mathematical host-parasite models accounting for gene-for-gene interaction and balancing natural selection. Observations agree well with theory.     

山区小流域自然资源垂直分异特征及其治理模式研究—以开县石碗溪流域为例

以开县石碗溪流域为例,论述了山区小流域自然资源的垂直分异特性,并在垂直分异的基础上,对该流域进行了综合分区,同时,结合成都山地灾害研究所在该地实施的生态项目,提出了垂直分异综合分区治理模式。     

黄土高原地区黄土裂隙发育特征及其规律研究

黄土中存在大量不同规模、不同成因、不同性质和不同时期的裂隙，不同裂隙之间的互相穿插、切割形成立体的网络裂隙系统。这些裂隙是分割黄土的结构面，是侵蚀土壤、洞穴的优势面，是孕育地质灾害的控制和分离面，是地下水的运移通道和储存场所，对其进行研究具有重要的科学和工程实践意义。本文对黄土裂隙进行了综合分类，系统总结了黄土高原地区自然营力作用下不同黄土裂隙的基本特征和发育规律，认为通常意义的黄土垂直节理主要是由黄土中的一部分不同成因的原生和次后期的垂向裂隙在黄土堆积过程中逐渐“生长”而成的。     

利用染色分析法确定农田土壤中硝态氮垂直运移的研究

利用农田土壤剖面染色并结合田间硝态氮示踪的方法,研究了太湖地区典型的水稻土—白土剖面中优势流和硝态氮在土壤剖面中的运移规律。结果表明:染色法可以分析土壤剖面中大孔隙的分布状况和优势流的路径;染色面积越大的土层,表明该土层的大孔隙含量就越高。在白土剖面上,表层的大孔隙含量最高,20~30 cm和55~100 cm土层以下大孔隙含量都很低。在田间条件下,优势流是影响硝态氮迁移的主要因素;白土剖面中优势流直接影响的最大深度为78 cm,对地下水的影响很大。本试验中地下水的硝态氮含量比未试验前增加了10多倍,这对环境安全影响极大。     

Influence of reward level on vertical distribution and growthof rainbow trout Oncorhynchus mykiss fed on demand with self-feeders

ABSTRACT:   The influence of reward level on vertical distribution and growthwas examined in rainbow trout fed on demand with self-feeders. Groupsof 15 trout with initial body weight of 140 g were maintainedat 14°C and feed access was restricted to a 12-h photophase.The trout received three reward levels with triplicates: 0.051 (low),0.089 (medium) and 0.267 g/kg fish/triggeractuation (high). Vertical distribution in the higher reward groupswas generally more even than that in the lower-reward groups, butthe behavioral characteristics of some individuals in a group couldplay an important role in determining vertical distribution. Moreover,no fish including the individuals responsible for trigger actuation,occupied the vicinity of a trigger. The small groups of 15 troutreceiving the medium-reward level obtained as much feed and grewas fast as the high-reward groups, but this was not the case forthe low-reward groups.     

秸秆压块机辊口式环模耐磨机理分析与试验

环模秸秆压块机成型过程中,由于秸秆颗粒与环模之间的滑动摩擦,环模模孔磨损十分严重,导致环模使用寿命缩短。以工字型模块组成的立式环模为研究对象,提出在工字型模块喂料端设置辊口式结构,即在工字型腰部上下两翼加工圆孔,孔中装配轴承和插入圆辊。通过相邻圆辊间所构成的辊口压入秸秆颗粒,从而将物料与原模块间因数较大的滑动摩擦变为物料与圆辊间因数较小的滚动摩擦,达到减小模孔磨损的目的。利用有限元软件分析得到改进前和改进后模孔处的磨损率曲线,结果表明:改进前环模最大磨损率0.11μm/s,改进后辊口式环模最大磨损率0.01μm/s,远小于改进前磨损率。通过试验表明所设计的辊口式环模具有减小磨损和延长环模寿命的作用。     

长春地区大豆田蓟马种类鉴定及黄蓟马种群动态

为了在大豆生产中更好地防治蓟马类害虫,于2017年长春地区的大豆田中调查蓟马种类及消长动态。结果发现,大豆田有1亚目2科5属6种蓟马,横纹蓟马(Aeolothrips fasciatus)、黄蓟马(Thrips flavus)、豆喙蓟马(Mycterothrips glycines)、齿裂绢蓟马(Hydatothrips dentatus)、烟蓟马(Thrips tabaci)和花蓟马(Frankliniella intonsa)。根据成虫特征编写了本地区大豆田蓟马种类识别检索表。调查发现,黄蓟马是本地区的优势种,发生高峰期为盛花期至始粒期。初步明确了该虫在大豆植株上的垂直分布规律:即主要分布于大豆植株上层叶片的第1叶位到第5叶位,主要在叶背面活动,成虫、若虫在各个物候期虫口数量与大豆叶位之间的关系以逻辑斯蒂模型拟合度较佳。     

西北旱区不同覆膜和灌溉水平下的玉米冠层氮含量垂直分布及高光谱反演

为探究不同覆膜和灌溉水平下玉米叶片氮含量垂直分布特征及其遥感反演规律,2020年在甘肃省武威绿洲农业高效用水国家野外科学观测研究站进行大田试验,设置3种灌水量水平(春玉米灌溉需水量的100%(W₁₀₀)、70%(W₇₀)和40%(W₄₀))和3种覆膜处理(不覆膜(M₀)、普通塑料膜(M₁)和生物可降解膜(M₂)),测定春玉米在不同灌水量和覆膜条件下叶片氮含量垂直分布、冠层反射特征和反射率与叶片氮含量等指标,并采用随机森林法构建氮含量估测模型分析垂直分布的叶片氮含量。结果表明,相同灌水处理的玉米冠层叶片中氮含量由高到低为M₀>M₂>M₁,M₀比M₂的上、中、下部位叶片氮含量分别增加6.78%、5.11%、2.55%,M₂比M₁的上、中、下部位叶片氮含量分别增加7.14%、5.24%、5.39%。...