不同pH条件对连作土壤微生态及辣椒的影响

在连作辣椒4年、pH值分别为5．2（连作4年原始土）6、7和8的土壤中,同时接种相同数量的拮抗菌（对照不加）,栽培辣椒（湘研205）;研究其对土壤微生态及辣椒生长发育等的影响。研究结果表明,在不同DH值条件下,随着辣椒生长期改变,微生物发生变化;在辣椒开花初期和盛果期,细菌、拮抗菌、放线菌数量pH为8的土壤最大,pH为6的土壤最小;真菌则相反。其次,与对照相比,不同pH值处理条件下的辣椒均比对照好,其中,pH为8的辣椒根活性、总产量最高;同时,死亡率低、受连作土壤影响少。因此,适宜的pH在益生菌的作用下,有利于连作土壤辣椒的正常生长。     

Distribution of DTPA‐extractable Fe,Zn, and cu in soil particle‐size fractions

Abstract

To examine the distribution of DTPA‐extractable Fe, Zn, and Cu in clay, silt, and sand fractions; surface soils were collected from cultivated fields of North Dakota, South Dakota, West Virginia, Iowa, Ohio, and Illinois. Clay, silt, and sand fractions were separated after sonic dispersion of soil water suspension and analyzed for DTPA‐extractable Fe, Zn, and Cu. In general, clay had the highest and sand the lowest amount of DTPA‐extractable metals. Consequently, clay had the highest and sand the lowest intensity and capacity factors for these metals since DTPA micronutrient test measures both these factors.     

不同工艺制备的水产开口饵料溶失规律试验研究

为了比较不同工艺制备的水产开口饵料中不同成分的溶失规律,试验对挤出滚圆法、挤出滚圆-流化床包衣法及膨化破碎法制备的饵料进行了质量损失率、粗蛋白溶失率、游离氨基酸(FAA)溶失率的比较研究,结果表明:膨化破碎工艺制备的开口饵料质量损失率、粗蛋白的溶失率和游离氨基酸的溶失率均高于挤出滚圆工艺;包衣没有明显改善饵料的溶失情况;游离氨基酸的溶失速度非常快,入水初期几乎全部溶失(5 min内溶失率就达到53.54%～91.71%)。     

增施绿肥与降低氮肥对小麦产量和土壤肥力的影响

在甘肃河西绿洲灌区,通过田间试验研究了增施绿肥7500kg/hm^2后减施无机N肥施用量对小麦产量、经济性状、土壤肥力和土壤微生物数量的影响。结果表明,绿肥＋70%N处理比当地农民习惯施肥模式（FFP）增产829～1525kg/hm^2,增产率为10.7%～22.9%,且土壤碱解N、速效P、速效K和有机质含量均较高,能...     

鲶卵膜形成的显微和超微结构比较的研究

光学显微镜观察鲶卵膜形成的显微结构,第1时相卵母细胞外具1层质膜。第2时相卵母细胞外可见到滤泡膜,第3时相卵母细胞时,可见到放射膜。第4时相初滤泡层和放射膜较前期更加增厚。第5时相卵母细胞外的滤泡膜已脱去。第6时相放射膜逐渐消解。透射电镜观察鲶卵膜形成的超微结构,在第2时相时,不仅具滤泡层,而且有鞘细胞层、基板和刚发生的放射膜,第3时相基板加厚。第4时相基板逐渐消失。第5时相滤泡细胞解体,放射膜的外层已经消失。对鲶卵母细胞膜发生的显微和超微结构作了比较,对卵膜的划分及分期、滤泡层的来源和构成、放射膜生成的机制等作了描述和探讨。     

河南省农业微观组织的现状调查与创新对策

农业微观组织对农业战略性结构调整和农业现代化建设起重要支撑作用，现状表明，农民家庭经营组织、农业社区性合作经济组织和农业产业化经营组织等微观组织需要在稳定的基础上积极创新。     

Study with isolated cuticles of the behaviour of zinc applied to leaves

In order to obtain a better understanding of the behaviour, at the cuticular level of Zn deposited on leaves in natural conditions, the cuticular retention and penetration of this element were studied in vitro, using enzymatically isolated cuticles from pear leaves (Pirns communis L. cv. Passe Crassane). The cuticular retention of Zn, supplied as 0,1 mM ⁶⁵Zn Cl₂ was related to plant species, increasing in the following order: Prunus armeriaca < Pirus malus cv. Golden < Pirus communis L. cv. William with a ratio Zn in cuticles (nmol/g)/Zn in the solution (nmol/g) varying from 282 to 613; it depended on the date of sampling of leaves, the results were apparently not connected with their age. Zn retained by the cuticular discs was lost partially by washing with water, and almost entirely with exchange solutions. The exchangeable fraction could not be precisely determined because of the progressive removal of ⁶⁵Zn from cuticles, with water. This lability was between that observed with ⁵⁴fin and ⁶⁴Cu . Interactions with Cu and Ca were considered, the cuticular retention of 0.1 mM Zn was drastically reduced from 0.01 mM only with Cu suggesting a high cuticular selectivity of Cu over Zn. The cuticular retention of Zn was higher with dewaxed cuticles probably because of a better access of Zn to fixation sites on the cuticular matrix.

The cuticular penetration of Zn was very slow through carefully selected cuticles but was faster with diluted HCl or non radioactive ZnCl₂ rather than with pure water in the receiver unit. The validity of results obtained with isolated cuticles is discussed.     

我国滴灌创新发展综述

我国是农业大国,农业作为用水大户,迫切需要大力推广节水灌溉技术.滴灌技术及设备是我国节水灌溉的重要组成部分,也是较早引入我国的节水灌溉模式.我国滴灌技术及设备走过了引进消化、示范推广、自主创新的发展阶段,为我国节水农业的发展做出了重要贡献.回顾了我国滴灌事业的创新发展历程,提出了发展区划及建议.     

砒砂岩区水力侵蚀下坡面微地貌变化特征及过程研究

解决砒砂岩区坡面的产流产沙问题对黄河流域生态安全具有重要意义,选取砒砂岩裸露坡面为研究对象,在自然降雨条件下采用野外径流小区实测结合三维激光扫描技术,分析13次有效降雨过程砒砂岩坡面微地貌的变化过程及产流产沙特征.结果表明,径流小区内坡面土壤平均侵蚀深度为26 mm,侵蚀区占径流小区总面积的95.27％,单位面积上侵蚀...     

小面积果园节水灌溉技术研究

针对我国苹果生产现状、水资源现状、经济条件以及管理水平,总结研究了几种简易节灌措施:微孔射流管、膜片式多孔管、加海绵加套管.在不同孔径、不同水压力下测得孔口泄流量,通过回归分析,确定出不同孔径的水压力与单孔泄流量的关系,然后利用勃拉修斯公式计算出满足一定的流量偏差率情况下的允许毛管长度.并现场测试采用计算毛管长度时的均匀系数,结果表明,上述3种节水灌溉方式,技术简单、价格低廉,适宜在经济落后、水资源短缺且有微小水源的干旱区使用.