沙地毛白杨速生丰产林节水灌溉的研究

以提高灌溉水利用为核心，以植物生理学和生态学以及树木生长为依据，连续８年对毛白杨速生丰产林节水灌溉的理论与技术进行了较为系统的，结果表明，利用科学的灌溉阈值，抓住关键的灌溉时期，确定有效的灌溉范围和经济的灌溉量，就可以较少的水分投入获取较高的林木生长量，在春夏干旱季节（０５－０６月），以田间持水量的５０％作为阈值实施灌水，具有极显著的近期和后期水分补偿效应，与较高灌溉水平（阈值为７０％）相比，灌溉水利用率提高４６．８０％，灌水量减少２２．８１％，材积生长量增加１３．３０％，经济效益提高３１．２８％。     

农田野花带群落构建及其稳定性特征

为维持农田野花带稳定性和持久性,以充分发挥其生态系统服务功能并扩大其应用范围,对8个不同建植年限(2、4和6年)的农田野花带混播群落的建立过程,包括群落密度、物种多样性指数以及不同寿命的初始植物和侵入植物重要值的变化规律进行了调查和分析.结果表明:1)播种建立的农田野花带群落,存在2次植物消亡,分别是一二年生植物和短命...     

蒸发降温和高蛋白对乳牛夏季生产性能的影响

选取泌乳中期黑白花乳牛12头,配对分为三组,蒸发降温为第1组,对照为第2组,高蛋白为第3组。第1组与2、3组除风速不同外,温湿指数(THI)相似。三组牛的直肠温度、呼吸频率和青草采食量没有显著差异,各组牛的直肠温度和呼吸频率与干球温度和THI呈极显著的正相关,青草采食量与其呈极显著的负相关。三组牛的产乳量相差极为显著,第1、3组分别较对照组提高16.68％和8.55％,第1组又较第3组提高7.46％。包括维持在内的产乳饲料利用率,第1、3组分别较对照组高6.6和2.9％。结果表明,蒸发降温和高蛋白均能显著提高夏季乳牛的产乳量,高蛋白不需特殊的设备,饲料成本亦较低,很有推广价值。据经济效益分析,第1组除去电力消耗外,每日每牛净收入可增加0.3209元,第3组增加0.7034元。     

种植密度对甜玉米品种华珍的影响

研究了不同种植密度对甜玉米品种华珍产量和主要农艺性状的影响。结果表明：从鲜穗或籽粒产量角度考虑,华珍的最佳种植密度为60000株／hm2;而从鲜穗种植效益角度考虑时,最佳种植密度为52500株/hm2。     

萝卜气吸式精量播种机的研制

对于目前国内还没有适用于萝卜种子大小的精量播种机现状,为了实现大面积种植萝卜作物的精量播种以及降低大面积播种的劳动力投入,减轻耕作的劳动量,提高劳动效率,研制了一种适用于大面积种植萝卜的精量播种机。该装置结构简单,使用时调整方便,具有起垄、开沟、播种、覆土和整形镇压等功能,可一次性完成播种作业,适用于大田作业。经田间试验证明:整机结构设计合理,单粒精播率高,镇压整形后的垄形符合农艺要求且外形美观。     

2BLM-3型留茬免耕播种施肥机的研制

以垄作与保护性耕作相结合为特点,在总结国内外先进技术经验的基础上,结合东北地区的实际情况,研制2BLM-3型留茬免耕播种施肥机。介绍该机的应用意义、总体设计思路及重要部件的设计方法,分析使用该机的经济效益、社会效益和生态效益,为改善东北地区的土壤肥力提供参考。     

影响水稻种绳直播机覆土厚度的主要因素研究

覆土厚度是水稻种绳直播机工作质量的主要评价指标之一。为提高种绳直播机的性能,通过正交试验研究影响覆土厚度的主要因素。经试验分析,得出开沟深度的调节值和机体作业速度为主要影响因素。     

Yield and growth characteristics for cotton under various irrigation regimes on sandy soil

Over-watering cotton wastes a valuable and scarce resource; it can also lead to rank growth, nutrient leaching, and contaminated groundwater. Since under-watering can decrease yields, the question becomes one of finding the optimum application regime. An irrigation experiment was set up to apply water at six different application rates, ranging from 33% to 144% of normal, with hopes of identifying the regime that produces maximum yield. Two cultivars, Acala Maxxa and Acala PhytoGen-72 (Gossypium hirsutum L.), were planted on sandy soil and irrigated daily with a highly efficient subsurface drip irrigation system for four seasons. The results showed that on the average there was no significant difference in the yield of the two cultivars and there was no significant difference in the yield for the three wettest treatments. The driest of the three wettest treatments, treatment 4, was a critical point on the water production function curve. It represented the least amount of water applied that still produced essentially maximum yield, and it had the highest water use efficiency. This critical level of water application during mid-season was found to be, on the average, 95% of Class A pan evaporation; it corresponded to a total seasonal application of 654 mm of water. Any application less than this critical level decreased yields. Reducing the water application by 5% below the critical level caused about a 4.6% reduction in yield. The critical level produced a soil moisture level that remained nearly constant throughout the season. The final plant height was closely related to the depth of water applied, with the wettest treatment producing plant heights of 2.0 m, and the driest treatment producing plant heights of 0.6 m. At the extremes of the water application rates there were some small differences in the early-season growth rate of the plants, but the main cause of differences in final plant height was the date of cutout (cessation of main stem node production). The length of season for the driest treatment was about 4 weeks shorter than for the wettest treatment on both cultivars. Results showed that deficit irrigation of cotton on sandy soil can greatly reduce yield, and the practice should probably be avoided.     

微咸水造墒对棉花生长发育及产量的影响研究

采用小区对比试验方法,研究了河北低平原区旱地等雨播种（HD）、播前淡水造墒（S1）以及矿化度为2.2g/L（S2.2）和5g/L（S5）微咸水造墒等不同处理对棉花生长发育和产量的影响。结果表明,棉花生育期内HD处理0～100cm土壤含水率明显低于3种造墒处理;S5处理0～40cm土壤盐分含量最高,但降雨淋洗效果较为显著...     

外槽轮式播种机播量控制系统设计与试验

为提高外槽轮式排种器播量调节范围与控制精度,设计了一种外槽轮式播量自动控制系统,该系统通过采集机组行进速度信号,同时控制槽轮转速与槽轮长度,实现播量调节与控制。通过试验,建立了播量与槽轮转速、有效工作长度的数学模型,分析了槽轮转速、有效工作长度对播量变异系数与模型精度的影响。结果表明:模型最大误差小于5%,平均误差为3. 2%,满足精度要求;槽轮有效工作长度在14～30mm范围内、转速为40～60 r/min时,变异系数小于0. 5%。上述参数范围是所设计外槽轮式排种器播量自动控制系统适宜的控制范围。研究为外槽轮排种器的播量自动控制策略提供了理论依据。