Responses of Lowland,Upland and Aerobic Rice Genotypes to Water Limitation During Different Phases

Rice yield reduction due to water limitation depends on its severity and duration and on the phenological stage of its occurrence. We exposed three contrasting rice genotypes, IR64, UPLRi7 and Apo (adapted to lowland, upland and aerobic conditions, respectively), to three water regimes (puddle, 100% and 60% field capacity) in pots during the vegetative (GSI), flowering (GSII) and grain filling (GSIII) stages. Stress at all the three stages significantly reduced yield especially in lowland genotype IR64. Effect of water limitation was more severe at GSII than at the other two stages. Stress at GSI stage reduced both source activity (leaf area and photosynthetic rate) and sink capacity (tiller number or panicle number per pot). When stress was imposed at GSII, spikelet fertility was most affected in all the three genotypes. In both GSII and GSIII, although leaf area was constant in all the three water regimes, estimated relative whole-plant photosynthesis was strongly associated with yield reduction. Reduced photosynthesis due to stress at any given stage was found to have direct impact on yield. Compared to the other genotypes, Apo had deeper roots and maintained a better water relation, thus, higher carbon gain and spikelet viability, and ultimately, higher biomass and productivity under water-limited conditions. Therefore, screening for these stage-dependent adaptive mechanisms is crucial in breeding for sustained rice production under water limitation.     

鄱阳湖水位特征与湿地生态保护

从分析江湖关系入手，研究鄱阳湖的水位及湿地生态特征，并提出人工控湖等加强湿地生态保护的对策建议。     

施用磷肥对环境的影响探讨

磷肥的施用与环境质量密切相关。本文讨论了过量施用磷肥加剧了农业非点源污染,农业非点源磷的累积增加了水体富营养化的风险,同时,磷肥中的重金属随磷肥的施用进入土壤环境,对土壤环境质量和农产品品质以及人体健康也有一定的影响。     

Effect of aggregate size and soil water content on emergence of soybean (Glycine max, L. Merr.) and maize (Zea mays, L.)

Rapid wetting of irrigated soils often leads to slaking and slumping, and on drying a surface crust and hard-set conditions may occur. This results in reduced crop emergence unless the surface is kept moist. The effect of aggregate size and water content on the emergence of soybean and maize from an Entic chromustert (heavy cracking clay) was determined using pots of sieved aggregates with size ranges less than 1, 1–2, 2–5 and 5–15 mm at soil water contents of 15, 20 and 25 g (100 g)⁻¹. Unsieved soil was used as a control. Greatest emergence tended to occur from fine (1–2 mm) seedbeds compared with coarse (5–15 mm) seedbeds for both crops. A covered treatment, simulating a stubble mulch, resulted in greater emergence than an uncovered treatment for all water contents and aggregate sizes. Earlier emergence occurred from finer (less than 1 mm and 1–2 mm) seedbeds than from coarse (5–15 mm) seedbeds, and at the greatest water content used. Soil strength, measured with a shear vane, decreased with increasing water content and tended to be less on fine (1–2 mm) seedbeds compared with very fine (less than 1 mm) or coarse (5–15 mm) seedbeds. It is recommended that, for good emergence from this Entic chromustert, seedbeds be brought to a water content of 25 g (100 g)⁻¹ by capillary wetting to prevent hardsetting and consist of 1–2 or 2–5 mm aggregates for soybean and maize, respectively, and have a stubble mulch on the surface. This corresponds to an equivalent depth of water of 15 mm and 9 mm for soybean and maize, respectively, in the top 50 mm of the profile.     

河北二季作区马铃薯节水灌溉研究初报

为研究河北二季作区马铃薯整个生育期不同灌水量对其生长发育的影响,以该地主栽品种为材料,根据不同生育期需水规律,设定5个不同水量梯度的滴灌处理和1个常规沟灌处理(CK);调查分析了不同处理间物候期、重要农艺性状、病害发生情况和产量等相关指标。结果表明,处理3(采用滴灌模式,水量为110 m3)与常规沟灌相比,马铃薯生长势、总产量和商品薯产量无显著差异,生育期提前,病害较轻,商品薯率提高7.2%,节水35.41%,综合表现优于其他处理,为试验地区最佳灌水量。     

新世纪首都水源区发展战略研究报告

作为首都郊区的密云县 ,应该自觉找准本县在首都经济中的战略地位 ,找到一条持续快速健康发展的道路。新世纪首都水源区的发展战略应该是 :着眼首都未来发展对水源和环境的高标准要求 ,切实履行高质量保护水源和环境的特殊职责 ;走环境立县、引进强县、科教兴县和依法治县之路 ;努力建设清洁优美的自然环境、先进完善的设施环境、高效规范的体制环境和健康和谐的人文环境 ;构建以高新技术工业、绿色农业、生态旅游业和环保节能型建筑建材房地产业为支柱的首都水源区经济体系 ;突出县工业开发区、密云卫星城与中心镇建设、旅游西线开发和畜牧业产业化四个战略重点 ,促进经济持续快速健康发展 ,实现强县富民的目标。     

磁处理水添食对家蚕若干数量性状影响的初步试验

研究了用不同强度磁处理水添食对家蚕生长及若干数量性状影响的生物效应。结果表明 ,从 3龄起连续添食磁处理水后与对照区比较 ,蚕体增长率提高 ,健康性和生命力有所增强 ,龄期经过缩短 1～ 2d ,茧质调查表明 ,全茧量、茧层量、茧层率等性状也都不同程度表现了正向效应 ,其中以场强为 2 0 0～ 30 0mT的磁处理水添食 ,作用效果较为显著     

月季切花真空预冷水分损失与补充的研究

以‘红衣主教’月季切花为试材进行了真空预冷中防止失水的研究。比较了三种不同预冷终温（１０、５、２℃）和两种不同补水方式（茎基吸水和叶面喷水）对月季花枝水分状况及瓶插寿命的影响。真空预冷过程中的鲜重损失以茎基吸水处理最小；叶面喷水次之；不给水处理最大。花朵水势测定结果表明，真空预冷后茎基吸水处理为－０．３～－０．４ｍＰａ，与处理前相近；叶面喷水则显著降低；不给水处理最低。不同处理的瓶插寿命，茎基吸水     

基于蒙特卡罗模拟的绿色建筑节水和中水回用的决策模型

通过对绿色建筑节水和中水回用项目的全寿命周期成本构成的分析,采用净现值衡量的指标形式,构建了绿色建筑全寿命周期经济决策模型,运用蒙特卡罗模拟的方法,以实际示范项目进行模拟应用,分别对绿色建筑和传统建筑的节水项目进行建模分析,实际验证了该模型和模拟方法的合理性和实用性,以期为绿色建筑项目的决策提供一种可借鉴、可操作的方法,以及为政府机构、决策部门和开发商的正确决策提供科学方法和理论依据.     

镧离子对苜蓿种子萌发活力、吸水量和膜透性的影响

20～700μg/ml的La(NO3)3处理的苜蓿种子吸水速率明显加快,膜的通透性增大,呼吸作用增强.其中,用500μg/ml La(NO3)3处理效果最佳,用1200～1500μg/ml La(NO3)3处理则抑制种子萌发.