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不同矿化度咸水造墒灌溉对棉花生长发育和产量的影响 总被引:3,自引:1,他引:2
采用裂区设计, 灌溉量作为主处理, 灌溉水的矿化度作为副处理, 研究了播前不同灌溉量下不同矿化度咸水对棉花生长发育及产量的影响。研究结果表明, 不同矿化度咸水灌溉对棉花出苗时间和出苗率的影响差异较大, 随灌溉水矿化度的增大, 棉花出苗速度变缓, 出苗率降低, 其中4 g·L-1 以下的咸水灌溉处理棉花出苗率在90%以上, 6 g·L-1 矿化度处理平均出苗率仍可达85%左右, 但出苗时间推迟。播种前咸水灌溉量以22.5~34.0 mm 为宜。灌溉水矿化度对棉花生长发育的影响程度前期大于后期, 前期大于4 g·L-1 矿化度处理表现出明显的抑制生长作用, 后期大于6 g·L-1 矿化度处理才表现出明显的抑制生长作用。从产量上看, 棉花的咸水矿化度计算阈值为3.38 g·L-1, 即在矿化度小于3.38 g·L-1 时, 咸水灌溉的棉花产量与淡水灌溉产量差异不明显, 高于此矿化度阈值时, 棉花产量呈直线下降趋势; 但低于8 g·L-1 咸水灌溉的棉花产量均显著高于纯旱地的棉花产量。 相似文献
996.
长期施肥和耕作管理对华北平原土壤肥力的影响 总被引:16,自引:0,他引:16
In the North China Plain, fertilizer management and tillage practices have been changing rapidly during the last three decades; however, the influences of long-term fertilizer applications and tillage systems on fertility of salt-affected soils have not been well understood under a winter wheat (Triticum aestivum L.)-maize (Zea mays L.) annual double cropping system. A field experiment was established in 1985 on a Cambosol at the Quzhou Experimental Station, China Agricultural University, to investigate the responses of soil fertility to fertilizer and tillage practices. The experiment was established as an orthogonal design with nine treatments of different tillage methods and/or fertilizer applications. In October 2001, composite soil samples were collected from the 0–20 and 20–40 cm layers and analyzed for soil fertility indices. The results showed that after 17 years of nitrogen (N) and phosphorous (P) fertilizer and straw applications, soil organic matter (SOM) in the top layer was increased significantly from 7.00 to 9.30–13.14 g kg-1 in the 0–20 cm layer and from 4.00 to 5.48–7.75 g kg-1 in the 20–40 cm layer. Soil total N (TN) was increased significantly from 0.37 and 0.22 to 0.79–1.11 and 0.61–0.73 g N kg-1 in the 0–20 and 20–40 cm layers, respectively, with N fertilizer application; however, there was no apparent effect of straw application on TN content. The amounts of soil total P (TP) and rapidly available P (RP) were increased significantly from 0.60 to 0.67–1.31 g kg-1 in the 0–20 cm layer and from 0.52 to 0.60–0.73 g kg-1 in the 20–40 cm layer with P fertilizer application, but were decreased with combined N and P fertilizer applications. The applications of N and P fertilizers significantly increased the crop yields, but decreased the rapidly available potassium (RK) in the soil. Straw return could only meet part of the crop potassium requirements. Our results also suggested that though some soil fertility parameters were maintained or enhanced under the long-term fertilizer and straw applications, careful soil quality monitoring was necessary as other nutrients could be depleted. Spreading straw on soil surface before tillage and leaving straw at soil surface without tillage were two advantageous practices to increase SOM accumulation in the surface layer. Plowing the soil broke aggregates and increased aeration of the soil, which led to enhanced organic matter mineralization. 相似文献
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为研究甘南地区欧拉羊杂交改良山谷型藏羊效果,对欧拉羊与山谷型藏羊杂交试验组和山谷型藏羊本交对照组所产后代的初生、3月龄、6月龄、12月龄、18月龄的体尺、体重进行了跟踪测定,并对不同年龄段杂交后代与对照组后代进行了对比分析和差异显著性检验。结果表明:杂交F1代初生、3月龄、6月龄、12月龄、18月龄的体尺、体重极显著的高于对照组(P〈0.01),初生、18月龄管围差异显著,3月龄、6月龄、12月龄管围差异不显著(P〉0.05)。 相似文献
999.
以国家退耕还林政策的实施为背景,结合三峡库区护岸林建设,通过对栽植于重庆涪陵南沱镇连丰村的笋用竹撑绿杂交竹3号护岸林的调查,测定了撑绿竹杂交3号在不同立地条件下的竹丛秆数、胸径、生长宽和竹高等生长因子,并分析了这些因子和立地条件的关系,采用F检验、SSR法多重比较,结果表明:坡向对竹高有极显著影响,阳坡竹子比阴坡竹子平均高1.30 m;土壤厚度对生长宽和竹高有显著影响,在40~60 cm厚的土层上竹子的生长宽比在20~40 cm厚的土层上的竹子生长宽平均宽0.20 m,竹高平均要高0.82 m;不同立地因子组合对竹高有极显著影响,平均竹高变化范围在7.47~9.54 m之间. 相似文献
1000.
Hongyu NIU Jie ZHANG Zhiyong WANG Guangchuan HUANG Chao PENG Hongmao ZHANG 《Integrative zoology》2020,15(2):115-126
Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals. However, exactly how the subordinate species coexists with superior species is unknown. In the forests west of Beijing City, intense asymmetrical interactions of food competition exist among granivorous rodents (e.g. Apodemus peninsulae, Niviventer confucianus, Sciurotamias davidianus and Tscherskia triton) that have broadly overlapping habitats and diets but have varied body size (range 15–300 g), hoarding habits (scatter vs larder) and/or daily rhythm (diurnal vs nocturnal). The smallest rodent, A. peninsulae, which typically faces high competitive pressure from larger rodents, is an ideal model to explore how subordinate species coexist with superior species. Under semi‐natural enclosure conditions, we tested responses of seed‐hoarding behavior in A. peninsulae to intraspecific and interspecific competitors in the situations of pre‐competition (without competitor), competition (with competitor) and post‐competition (competitor removed). The results showed that for A. peninsulae, the intensity of larder‐hoarding increased and the intensity of scatter‐hoarding declined in the presence of intraspecifics and S. davidianus, whereas A. peninsulae ceased foraging and hoarding in the presence of N. confucianus and T. triton. A. peninsulae reduced intensity of hoarding outside the nest and moved more seeds into the nest for larder‐hoarding under competition from intraspecific individuals and S. davidianus. In most cases, the experimental animals could recover to their original state of pre‐competition when competitors were removed. These results suggest that subordinate species contextually regulate their food‐hoarding strategies according to different competitors, promoting species coexistence among sympatric animals that have asymmetrical food competition. 相似文献