Analysis of Phosphorus Nutrition Efficiency of Soybean Genotypes with Different Phosphorus Efficiency at Blooming Stage under Low Phosphorus Stress

[Objective] This study aimed to investigate the phosphorus nutrition effi- ciency of different soybean genotypes at blooming stage under low phosphorus stress. [Method] By using four ＂low phosphorus efficiency＂ soybean genotypes （D03, D05, D17 and D18） and four ＂high phosphorus efficiency＂ soybean genotypes （D31, D34, D37 and D38） as experimental materials, soil culture experiment was conduct- ed with two treatments of high phosphorus （＋P） and low phosphorus （-P）, to analyze the relationship between phosphorus content, phosphorus uptake, phosphorus use efficiency and phosphorus efficiency of soybean genotypes with different phos- phorus efficiency. [Result] Under low phosphorus conditions, four soybean genotypes with high phosphorus efficiency showed significant advantage in phosphorus uptake at seedling stage, to be specific, D34 showed relatively high phosphorus absorption capacity but no advantage in adaptability of phosphorus use efficiency, while only D37 showed relatively high phosphorus absorption capacity and phosphorus use ca- pacity. Correlation analysis and path analysis showed that the level of phosphorus efficiency of soybean at blooming stage under （-P） and （＋P） treatments was mainly determined by phosphorus absorption capacity, and that under （-P） treatment was significantly greater than （＋P） treatment. Phosphorus uptake and phosphorus use ef- ficiency under （-P） and （＋P） treatments both showed great direct effects on phos- phorus efficiency, and phosphorus uptake made greater contribution; however, the indirect effects were relatively low, Under low phosphorus stress, the mechanisms for various soybean genotypes with high phosphorus efficiency to adapt to low phospho- rus stress were different, and phosphorus absorption efficiency （phosphorus uptake） was the main variation source of the phosphorus efficiency of various soybean genotypes at blooming stage. [Conclusion] This study revealed the contribution made by phosphorus absorption efficiency and phosphorus use efficiency to phosphorus efficiency of soybean.

温室大棚用电动微耕机研制

根据设施农业环境特点,设计了电动微耕机结构形式及传动系参数,开发了温室大棚用供取电系统及单输入三输出变频调速系统,并对电动机及变频调速系统进行了试验研究,研制了一种温室大棚用电动微耕机系统。研究结果表明:在变频调速系统控制下的电动机具有低速恒转矩、高速恒功率的输出特性,能够较好地满足温室大棚作业工况需求;随着转速增大电动机输出效率增大,当转速达到1 500 r/min时,最高效率达到84.6%;当输出转速降至1 200 r/min时,电动机效率仍能够达到81.7%,具有较宽的高效调速范围;所研制电动微耕机安全性能等指标符合相关标准规定,且具有低噪声、零污染的特点;其单位小时的耕作效率约为2.29亩,略高于同功率汽油微耕机;每亩耗电量约为0.46kW.h,其经济性能远高于同功率的汽油微耕机。

论我国农地制度的变迁模式与绩效——基于农村与国有农场两类经验的比较

制度创新是改善经济绩效的重要手段,农地制度改革的目标是优化土地资源配置,以提高农业经营效率。我国农地制度改革主要通过国家政策调整的方式实现。以第二轮土地承包为契机,国家政策干预从基本经营体制方面,深入到农村集体内部的地权配置上,打破土地集体所有制基础上的土地承包自主合约关系,走上了强制性制度变革模式。在较少的政策干预下,国有农场自经营体制变革以来,一直保持农地制度诱致性变迁模式,农场内部的资源配置通过自由协商完成。国有农场基于自主合约完成的地权配置,在农业生产和资源配置方面皆具有优势。国有农场的土地制度安排,构成了农村土地制度改革的经验参照。

华北平原种养一体规模化农场氮素流动特征及利用效率——以河北津龙循环农业园区为例

种养一体规模化、集约化是华北平原农业发展的必然趋势,而氮素是连接种植养殖的主要养分资源,以河北津龙循环农业园区为例,采用文献资料、实地调查方法分析农场水平氮素流动特征及利用率,并通过情景分析方法提出农场氮素管理措施,为实现农场水平氮养分资源高效利用、提高农场生产系统生产力和改善华北平原循环农业模式提供技术支撑和科学依据.结果表明:在农场水平下,化肥和有机肥输入氮量674.6 kg·hm^(-2)·a^(-1),占总输入氮量的88.3%,氮利用率为41.5%,种植系统氮盈余量190.7 kg·hm^(-2)·a^(-1),施氮量过多是造成种植系统氮利用率低和氮素盈余量高的主要原因.养殖系统中外购饲料提供氮量占饲料总输入氮量的83.2%,粪尿排氮量为776.6 t·a^(-1),而还田比例仅为36.3%,氮利用率19.7%.农场水平氮总利用率为40.7%.情景分析表明,农田减少化肥施氮量50%(情景1)、增加来自农场内部玉米籽粒产量(情景2)措施,可分别使种植系统氮利用率提高34.6%和15.6%,同时农场水平氮总利用率分别提高18.7%和9.8%;另外,优化养殖系统饲料结构(情景3),可使氮总利用率提高19.1%.因此,减少化肥氮施用量、调整作物种植结构、优化饲料结构等,是提高农场氮生产力和实现环境友好双赢效果的措施和途径.