不同温湿度及光照强度对烟蚜繁殖的影响

[目的]明确不同温湿度及光照强度对烟蚜繁殖的影响,提高烟蚜的繁殖效果.[方法]在不同温湿度和光照强度下培养烟蚜,对烟蚜的种群年龄结构、繁殖效果进行分析.[结果]不同温湿度和光照强度对烟蚜繁殖影响较大,在相对湿度较低、光照充足条件下有利于烟蚜生长发育,病害发生较低,繁殖效果较好.[结论]试验结果为毕节市烟蚜茧蜂防治烟蚜提供了理论依据.     

Interannual and interdecadal variability in juvenile coho salmon (Oncorhynchus kisutch) diets in relation to environmental changes in the northern California Current

The feeding habits of juvenile coho salmon, Oncorhynchus kisutch, in the northern California Current were examined using samples from two different time periods (1980–85 and 1998–2003) of highly contrasting oceanographic conditions. The goal was to test the influence of interannual and interdecadal changes in taxonomic composition of prey, feeding intensity, and size spectra of teleost prey. Analyses were done for samples taken both early in the summer (June) shortly after the salmon enter the ocean, and also in late summer (September) following some ocean residency. Fish prey dominated coho salmon diets by weight during most years, but this trend was more pronounced during the 1980–85 sampling period. In terms of numerical composition, the diets were more variable on an interannual basis, but decapod larvae and euphausiids were important prey in most years. Pteropods and copepods were important prey during weak upwelling or El Niño years, whereas euphausiids were important during strong upwelling or otherwise highly productive years. Hyperiid amphipods comprised a substantial proportion of the diets only in 2000. Coho salmon showed highly significant differences in prey composition among years or between decades both in weight and numerical composition. The percentage of empty stomachs was highly variable by year in both June and September, but was significantly different only for September between decades. In contrast, an index of feeding intensity did not show many significant changes in either comparison. However, the relative size ratios for fish prey consumed were highly variable by year, and larger than average fish prey were consumed during 1998, leading to the highest feeding intensity observed.     

Comparisons of Various Chemical Extracts as Quantity Factors to Determine Metal-Buffering Capacity of Soils

Applicability of various chemical extracts was investigated as quantity (Q) factors to determine cadmium (Cd), zinc (Zn), and copper (Cu) desorption quantity–intensity (Q/I) relationships in soils. The metal extracts were sums of sequential metal fractions (except the residual fraction) using Tessier's (TSE) and Community Bureau of Reference (BCR) procedures and various single chemical extracts: 1.0 M potassium nitrate (KNO₃), 1.0 M magnesium nitrate [Mg(NO₃)₂], 1.0 M magnesium chloride (MgCl₂), and 0.11 M acetic acid (CH₃COOH) solutions. Water-extractable metal was applied as a fixed intensity (I) factor. The TSE or BCR metal fractions were significantly correlated with diethylenetriaminepentaacetic acid (DTPA)–extractable metals, and all the metal desorption Q/I curves were linearly fitted. However, most of metal BC values estimated by using the single chemical extracts were very low and did not have consistent trends for target metals. Only 0.11 M CH₃COOH-extractable metals might be reliable. Therefore, TSE and BCR metal fractions can be applicable to replace DTPA-extractable metals, and 0.11 M CH₃COOH-extractable metals might also be useful.     

Influence of Light Intensity on the Yield and Quality of Houttuynia cordata

Abstract

The contents of major nutrient components, and the composition and contents of medicinal substances were examined in Houttuynia cordata cultivated under field conditions and treated with natural light at full intensity, 40% intensity, and 20% intensity from sprouting to harvesting. The results indicated that the yield of the aboveground portion per unit area was highest at a 40% intensity and lowest at 20% intensity. The yield of the underground portion per unit area was highest under full intensity and lowest at a 20% intensity. As light intensity was reduced, protein and water content increased, while the contents of soluble sugar and fat, the contents of volatile oils both the aboveground and underground portion decreased. The total flavonoid content in both the aboveground and underground portions decreased with diminishing light intensity, but the composition of these flavonoids was hardly affected. In summary, although proper shading can increase the yield and the contents of some nutrients in H. cordata, this treatment reduces the net contents of medicinal components such as volatile oils and flavonoids, as well as the contents of active components. Therefore, it is necessary to provide sufficient light when growing H. cordata for medicinal and functional food purposes, but the crop may be treated with appropriate shading or intercropped when grown as food.     

几种生态因子对银纹夜蛾实验种群的影响

本文以主要质量指标对比了用人工半合成饲料与天然饲料饲养银纹夜蛾的结果，表明人工半合成饲料明显优于天然饲料。研究了幼虫饲养密度对存活的影响，四龄末幼虫存活率与一龄幼虫密度呈抛物线关系，化蛹率、蛹重与五幼虫密度呈直线下降关系，相对湿度、夜间光照强度、食物等对成虫生殖有显著影响。     

非灌溉条件下不同年龄梭梭蒸腾耗水比较

通过野外的实际观测,研究2龄、3龄和4龄植物群落区的土壤水分差异及其对梭梭(Haloxylon ammodendron)蒸腾耗水的影响.结果表明:(1) 种群年龄增加,土壤水分显著降低,裸地、2龄、3龄、4龄种群0～200 cm土层年平均土壤水分含量分别为74.40,66.08,52.71 mm和49.23 mm;(2) 生长初期,不同年龄间梭梭蒸腾速率差异不明显,盛夏,3龄梭梭蒸腾速率最大,生长后期,梭梭蒸腾速率随群落年龄增加而减小;(3) 种群年龄增加,梭梭长势停滞,水分消耗减少,2龄、3龄和4龄梭梭平均株高分别为71,132,75 cm,平均冠幅分别为54 cm×57 cm,80 cm×123 cm,58 cm×63 cm,年均蒸腾耗水分别为33 603.0,98 827.1,32 231.5 g.选择合理的密度配置方式,对维持人工植物群落与土壤水分的相对稳定具有十分重要的作用.     

遮光处理对容器育柑桔幼苗生长与微环境的影响

以德尔塔（Delta）甜检和中熟娜特（Midknight）甜橙两个品种为材料,探讨不同颜色遮光网、遮光强度与遮光时间对容器育柑桔幼苗生长、水分利用、叶片净CO2代谢速率以及幼苗生长微环境如土壤温度、大气湿度的影响。结果表明：与对照相比,所有遮光处理的幼苗较高,茎干较粗,德尔塔甜橙的试验结果比中熟娜特甜橙明显;遮光5个月比遮光12周的处理效果更明显;不遮光处理利用较多的水分．途光处理间无明显差别;不这光处理的土壤温度在14：00显著高于所有遮光处理;各处理间叶片净CO2代谢速率和大气湿度无差别。     

稻纹枯病预测法的研究

对稻纹枯病１６ａ流行资料的统计分析表明：稻纹枯病的流行强度，主要受发生前的１月上旬雨量，１月下旬、４月下旬相对湿度或发生期间的６月下旬温雨系数，７月中旬降雨积数以及８月中旬上候温湿系数所决定。根据这些因子进行列联表法和回归模型法预测稻纹枯病流行强度，回测符合率高，试报效果好。     

宁南山区不同放牧强度对天然草地土壤水分的影响

本文对位于宁夏南部黄土高原半干旱区过渡放牧区、中度放牧区和持续禁牧三种条件下的天然草地 0 - 9.9m土壤深度的水分含量进行了测定。三者土壤水分含量的主要差别在 0 - 4m以上土层。 0 - 4m土层的土壤湿度 ,核心保护区显著 ( p =0 .0 2 2 838)高于中度放牧区 ,极显著 ( p <0 .0 0 1 )高于过渡放牧区 ,中度放牧区也显著高于过渡放牧区 (p =0 .0 2 80 2 3)。平均土壤湿度 ,核心保护区分别是中度和过渡放牧区的 1 .2 5和 1 .5 6倍 ,中度放牧区是过渡放牧区的 1 .2 5倍。 4- 9.9m土壤湿度 ,核心保护区、中度放牧区和过渡放牧区没有显著差异 ,平均土壤湿度分别为 1 2 .3%、1 2 .7%、1 2 .7%。     

热激处理及贮藏温度对水蜜桃果实生理生化变化的影响

研究了热空气处理和贮藏温度对水蜜桃硬度，果皮色泽，色素含量，呼吸作用。乙烯释放，脂肪氧合酶（LOX）与过氧化物酶（POD）活性的影响。结果表明：40℃热空气处理24小时可保持果实的硬度，抑制果皮中叶绿素的降解，推迟了呼吸高峰的出现，保持了细胞膜的完整性，热处理抑制了乙烯的释放，降低了LOX和POD活性。