氮在水稻中的行为及其品种间的差别

目前氮肥的利用效率很低，很多研究重点放在氮肥在土壤过程中的损失，对植物本身的氮素损失较少注意。作者利用^15NH4^ 和^15NO3^-双标记，对Indica和Japonica水稻亚种进行水培，在分蘖期、幼穗分化期、开花期施用，将培养液ρ(N)20mg／L的NH4NO3换成相同质量浓度的^15NH4^ NO3或NH^15NO3^；部分水稻在一周后收获，其他分别在分蘖期、幼穗分化期、开花期、成熟期收获。植株分成根系、地上部和穗部，对各自的全氮、^15N进行测定，计算植物的总吸收量。从施用量、植株总吸收量以及三部分总和的植株氮残存量的比较来研究氮素在两种水稻亚种中的行为。研究结果表明，两种植物都近100％吸收了所施用的^15NH4NO3或NH4^15NO3，但^15NH4^ 和^15NO3^-在Japonica的残存量要比Indica多，损失的部分可能往大气中散失了，意味着两种水稻亚种有着明显不同的氮素利用率。比较^15NH4^ 和^15NO3^-的残存量，结果表明^15NH4^ 留在植株体内要比^15NO3^-多，尤其在抽穗期施用的情况下，植物体在后期对^15NO3^-的转化能力大大减弱，但这部分的氮如何损失掉尚不清楚。比较植株体内各部分的氮素含量，发现Japonica的穗部比Indica含有更多的氮素，表明氮在前者的体内转化效率和利用效率高。试验结果表明，不同水稻亚种对氮素的利用以及不同氮素形态在其体内的行为不同。     

磁性肥料及其对水稻生长的影响研究

磁性肥料能明显促进水稻的生长和提高生物产量，在以广州发电厂的粉煤灰为主要磁性物质时，对赤红壤和水稻来说，其磁性肥料磁处理的最佳磁感应强度是０．２２Ｔ．     

Durability of conventional concretes containing black rice husk ash

In this study, black rice husk ash (BRHA) from a rice mill in Thailand was ground and used as a partial cement replacement. The durability of conventional concretes with high water–binder ratios was investigated including drying shrinkage, autogenous shrinkage, depth of carbonation, and weight loss of concretes exposed to hydrochloric (HCl) and sulfuric (H₂SO₄) acid attacks. Two different replacement percentages of cement by BRHA, 20% and 40%, and three different water–binder ratios (0.6, 0.7 and 0.8) were used. The ratios of paste volume to void content of the compacted aggregate (γ) were 1.2, 1.4, and 1.6. As a result, when increasing the percentage replacement of BRHA, the drying shrinkage and depth of carbonation reaction of concretes increased. However, the BRHA provides a positive effect on the autogenous shrinkage and weight loss of concretes exposed to hydrochloric and sulfuric acid attacks. In addition, the resistance to acid attack was directly varied with the (SiO₂ + Al₂O₃ + Fe₂O₃)/CaO ratio. Results show that ground BRHA can be applied as a pozzolanic material and also improve the durability of concrete.     

四川不同海拔稻田生态条件与杂交水稻生长发育及其应用研究

对φ（Ｎ）３２°１４′～３２°５６′,λ（Ｅ）１０４°３６′～１０４°５１′范围内４００～１４００ｍ稻田小气候进行了观测,发现海拔（ｈａｌｔ）不同,稻田生态环境相差很大：ｈａｌｔ每升高１００ｍ,平均气温（θａｒ）递减０．７２℃,年降雨量递增６３．０ｍｍ（４００～６００ｍ）～１０６．８ｍｍ（８００～１４００ｍ）,相对湿度递增１％,日照时数呈抛物线上升变化．ｈａｌｔ４００ｍ日均温稳定通过１２．０℃的初期为３月中旬,ｈａｌｔ每升高１００ｍ,该时间延迟５～７ｄ．不同ｈａｌｔ＞１２℃的有效积温分别为３６２１．２℃（４００ｍ）、３２４５．０℃（６００ｍ）、３１４９．９℃（８００ｍ）、２８０４．８℃（１０００ｍ）、２０８２．１℃（１２００ｍ）、１９５０．１℃（１４００ｍ）．在相对较高的ｈａｌｔ,存在明显的逆温和南北坡效应,相应存在杂交水稻局部高产区．本研究结果为四川不同海拔区杂交水稻品种合理布局和应用高产优质栽培技术提供了基础理论依据     

广州市不同区域水稻质量状况及其污染源探讨

根据1999年度对部分水稻质量监测结果,认为产品质量为重污染级这一问题,于2001年再选择一些监测点开展水稻质量、生产环境质量监测和评价。结果表明,2001年度水稻质量仍存在受污染问题,污染因子为氟化物、铅、镉和汞,大气污染为主要原因,其次为水质污染。     

长江中下游地区高温热害对水稻的影响

以长江中下游地区的气象资料和水稻生长发育观测资料为基础,应用WOFOST作物模型模拟了不同发育时段高温热害对早稻和中稻生长发育及产量的影响,评估了长江中下游地区高温热害对水稻的影响程度.研究表明:高温主要影响早稻和中稻的孕穗、开花和灌浆,受高温影响减产程度依次为灌浆期最大,开花期次之,孕穗期最小;当高温强度和持续日数增...     

盐胁迫下耐盐与盐敏感水稻的RAPD和POD同工酶检测

对耐盐、一般耐盐和盐敏感３种水稻材料进行了ＲＡＰＤ和同工酶检测,结果发现：３３个引物（Ｎ－１－Ｎ－１２,Ｓ４５０－Ｓ４７０）中,２７个引物具有拉增产物,拉增片段大小分布在０．２－３．４ｋｂ之间,说明在一定程度上反映了３种对盐具有不同耐盐性水稻在基因组ＤＮＡ分子水平上的差异,以Ｓ４５０为引物,在强耐盐的７７９中扩增出１个１．１ｋｂ的特异ＤＮＡ片段（Ｓ４５０１１００）,而在对盐敏感的早花２号中,以Ｎ－     

土壤施硅对水稻吸收砷的影响

通过盆栽试验研究在2种砷污染土壤中施加硅对水稻幼苗吸收砷的影响.结果表明,施加外源硅没有显著提高幼苗期水稻植株地上部和地下部生物量,也没有显著影响低砷土壤中水稻植株地上部和地下部的磷浓度,却使高砷土壤中水稻植株地上部磷浓度增加18%～39%,但对地下部磷浓度影响不大.同时与不施硅相比,无论是否调节硅酸钾溶液的pH值,施加2种浓度的外源硅均显著降低水稻植株地上部和地下部砷浓度.在低砷土壤中施加2种浓度的外源硅使水稻植株地上部砷浓度降低36%～59%,地下部砷浓度降低15%～37%.在高砷土壤中加硅,地上部砷浓度降低42%～58%,地下部砷浓度降低70%～82%.此结果与水培试验结果相一致,并对可能的机理进行了解释.     

我国近地层臭氧污染对水稻和冬小麦产量的影响概述

地表监测数据表明,我国近地层O3污染日趋严重,已对水稻和冬小麦的生长造成严重威胁。为评估O3污染对我国农业生产的风险,综合已有剂量反应实验结果,对我国南北五个地区(北京、定兴、江都、嘉兴、东莞)水稻和冬小麦的O3敏感性进行了比较分析。研究发现:(1)随着实验地区和实验品种的变化,两种作物的O3敏感性存在明显差异,其中,水稻对O3的敏感程度由北到南逐渐增加;(2)两种作物的产量均随O3剂量的增加而降低,且冬小麦的减产程度高于水稻;(3)基于FACE实验得到的作物O3敏感性高于基于OTC实验的研究结果。利用上述研究得到的O3剂量反应方程和O3浓度预测数据,对未来我国水稻和冬小麦的产量损失进行了评估。预计到2020年,我国五个主要作物产地水稻和冬小麦的产量损失范围分别为3.2~28.8%和7.8~36.9%。上述结果表明,O3污染已对我国主要粮食作物的生长造成巨大威胁,且作物品种间存在明显的O3抗性差异,有必要采取有效措施缓解O3浓度的上升,同时,需要利用更科学的实验方法进行O3抗性品种的选育,这对降低O3的农业风险具有重要意义。     

Determination of Cd,Cr, Cu,Pb and Zn from various water samples with use of FAAS techniques after the solid phase extraction on rice bran

A facile and novel method has been developed for the determination of cadmium, chromium, copper, lead, and zinc from various water samples using FAAS. In the present investigation, a syringe was loaded with sorbent (rice bran) for the separation and enrichment of cadmium, chromium, copper, lead, and zinc, prior to their analysis by flame atomic absorption spectrometry which was described to substitute the batch and column techniques. The syringe was loaded with 2.0 g of sorbent in order to retain the analyte elements. Six milliliter of sample solution (pH 8.0 ± 0.2) was drawn into the syringe in 15 s and discharged over a period of 15 s. Then, 2.0 M HCl eluent was drawn into the syringe and ejected back to desorb the analyte elements. At the optimum conditions, the percentage recoveries of Cd, Cr, Cu, Pb, and Zn was in the range of 95.5–99.4% with SD of 0.10%. The elements could be concentrated by drawing and discharging several portions of sample successively. The detailed study of various interferences made the confirmation of the method highly selective. The risk of contamination is less than that with the column technique. The method was successfully applied for the determination of Cd, Cr, Cu, Pb, and Zn in spiked and natural water samples. The results obtained are in good agreement with the reported methods at the 95% confidence level.