Leaf K/Na ratio predicts salinity induced yield loss in irrigated rice

Salinity is a major constraint to irrigated rice production, particularly in semi-arid and arid climates. Irrigated rice is a well suited crop to controlling and even decreasing soil salinity, but rice is a salt-susceptible crop and yield losses due to salinity can be substantial. The objective of this study was to develop a highly predictive screening tool for the vegetative growth stage of rice to estimate salinity-induced yield losses. Twenty-one rice genotypes were grown over seven seasons in a field trials in Ndiaye, Senegal, between 1991 and 1995 and were subjected to irrigation with moderately saline water (3.5 mS cm^-1, electrical conductivity) or irrigation with fresh water. Potassium/sodium ratios of the youngest three leaves (K/Na_Leaves) were determined by flame photometry at the late vegetative stage. Grain yield was determined at maturity. All cultivars showed strong log-linear correlations between K/Na_Leaves and grain yield, but intercept and slope of those correlations differed between seasons for a given genotype and between genotypes. The K/Na_Leaves under salinity was related to grain yield under salinity relative to freshwater controls. There was a highly significant correlation (p < 0.001) between K/Na_Leaves and salinity-induced grain yield reduction: the most susceptible cultivars had lowest K/Na_Leaves and the strongest yield reductions. Although there were major differences in the effects of salinity on crops in both the hot dry season (HDS) and the wet season, the correlation was equally significant across cropping seasons. The earliest possible time to establish the relationship between K/Na_Leaves under salinity and grain yield reduction due to salinity was investigated in an additional trial in the HDS 1998. About 60 days after sowing, salinity-induced yield loss could be predicted through K/Na_Leaves with a high degree of confidence (p < 0.01). A screening system for salinity resistance of rice, particularly in arid and semi-arid climates, is proposed based on the correlation between K/Na_Leaves under salinity and salinity-induced yield losses. This revised version was published online in July 2006 with corrections to the Cover Date.     

栽培管理对农田土壤呼吸的影响及减排途径

在全球变化加剧背景下,农田碳排放问题越来越引起人们的关注.结合国内外已有的相关报道,系统综述了栽培管理措施对农田土壤呼吸影响的差异,探讨栽培管理措施影响土壤呼吸速率的可能机制,并提出了农田土壤碳减排可行的管理措施,展望了未来该领域应加强的研究方面,旨在为农田生态系统在全球变化背景下碳汇功能的发挥提高理论依据和技术指导.     

减氮配施微生物菌剂对烤烟产量和品质的影响

为探究减氮条件(比传统施肥减氮21.49%)下配施微生物菌剂对烤烟产量和品质的影响,采用施肥模式(传统施肥和减氮21.49%)微生物菌剂(根茎康微生物菌剂)的双因素试验,比较不同处理烤烟的生长性状、化学成分、感官质量和经济效果差异,采用效应值(η2)分析施肥模式、微生物菌剂及其互作对烤烟产量和品质的贡献率。结果表明：减氮配施微生物菌剂可改善中、上部烟叶物理特性,上、中、下部烟叶的总糖含量和上部叶钾含量分别提高了15.47%、9.03%、81.41%、16.28%,上、中、下部烟叶感官质量分别提高了5.92%、6.93%、7.36%,正组烟比例提高了10.75%,青杂烟比例降低了55.35%;氮肥偏生产力和氮肥偏生产效率分别提高了20.31%、32.95%;施肥模式、微生物菌剂及其互作对烤烟生长性状贡献率分别为37.25%、38.83%、23.92%,对烟叶化学成分贡献率分别为39.04%、31.64%、29.32%,对烟叶感官质量贡献率分别为54.48%、39.26%、6.26%,对烟叶经济效果贡献率分别为37.57%、32.52%、29.91%。     

施氮对不同小麦品种光合荧光特性及产量的影响

[目的]研究减氮处理对不同小麦品种光合特性、叶绿素荧光及产量的影响,为氮高效利用型小麦品种资源的选择提供理论基础.[方法]大田滴灌条件下,以冬小麦品种(品系)新冬20号、新冬40号、新冬57号、新冬60号、新粮801、新粮802和新粮803为材料,分析不施氮肥(N0)和正常施氮(N1)处理,对不同小麦品种叶绿素相对含量...     

设施蔬菜肥料施用现状调查分析及减施潜力估算

对赤峰市典型设施农业区20个种植户进行施肥情况调查。结果表明：赤峰市设施农业有机肥投入量偏高,化肥以基施为主。赤峰市设施蔬菜调查区氮、磷、钾养分总投入量平均分别达 2575、1266、2790 kg/hm _² ,土壤养分投入过大养分过量现象严重。每季黄瓜、番茄、辣椒 N∶P ₂ O ₅ ∶K ₂ O 平均为1:0.49:1.09,养分比例适中。施入土壤的养分总量远超过各自推荐施肥量,养分减施潜力较大。赤峰市设施蔬菜应大力推广测土配方施肥技术,实现资源节约型、环境友好型现代化高效农业。     

45℃人工加速老化对不同品种小麦种子生理生化特性的影响

以百农160、百农矮抗58和泛麦8号3个小麦品种为材料,人工老化处理时间分别为0、1、2 d,结果表明:发芽率随处理时间的变化不大、TTC还原强度随处理时间的增加逐渐降低、可溶性糖含量和丙二醛含量随着处理时间的延长逐渐升高,尤其百农矮抗58小麦的变化明显。     

节能减排视角下我国农村节能灯的推广研究

通过对湖南省部分农村地区节能灯使用现状的调查研究,分析了农村地区所出现的节能灯“不经济、不节电、不环保”等问题出现的原因,探讨了制约”白炽灯淘汰难、节能灯推广难”的障碍,提出了相应的解决策略。     

Physiological Changes and Cold Tolerance of Three Camphor Species During Natural Winter Temperature Fluctuations

The dynamic changes in the malondialdehyde（MDA）, superoxide dismutase（SOD）, soluble sugar, proline, and soluble protein contents, as well as the relative electrolyte conductivity and the corresponding cold resistance, of Cinnamomum bodinieri Level., C. camphora L., and C. caudiferum Kisterm were investigated during the winter months of October 2009 to April 2010. During the short period of temperature decline that lasted until mid-December, the changes in the relative electrolyte conductivity and MDA content with temperature were insignificant. In January, SOD activity continued to increase and then peaked as a result of rapid increases in soluble sugar, proline, soluble protein, as well as the inhibition of the relative electrolyte conductivity and decrease in MDA content. These physiological changes protected the camphor trees from cold damage during winter. From February to March, SOD activity and the soluble protein and proline contents increased with the increase in temperature. However, the relative electrolyte conductivity and MDA content decreased, indicating that the cell membrane damaged by low temperature was gradually being repaired. The cold dip in April led to slight increases in the relative electrolyte conductivity and MDA content. Using a fuzzy mathematics method, the cold resistance adaptability of the camphor trees was divided into three periods namely, the enhancement setting stage, the vigorous stage, and the reducing stage. The cold tolerance abilities were ranked as the following order： C. bodinieri Level〉C. camphora L.〉C. caudiferum Kisterm.     

气候变化背景下大兴安岭地区森林火灾减灾效益评价

森林火灾是一种重要的生态因子,会引起其他生态因子的重新分配,具有调节和调控森林生态系统的结构和功能、维护某些物种生存的作用。该文对大兴安岭地区森林减灾效益作出评价,提出科学的林火管理建议,希望在以后的大兴安岭森林防火实践中起到帮助作用。     

5种红豆杉的生态效益比较

在野外自然条件下,测定了中国红豆杉（Taxus chinensis）、云南红豆杉（T. yunnanensis）、东北红豆杉(T. cuspidata)、南方红豆杉（T. chinensis var. mairei）和曼地亚红豆杉（T. media cv Hicksii）等5种红豆杉植物的叶面积指数、光合与呼吸速率、蒸腾速率等指标,计算了释氧固碳量和降温增湿量,比较了它们之间的生态学效应。结果表明,不同种类红豆杉的生态效益存在差异,降温增湿和释氧固碳能力均以曼地亚红豆杉最强,南方红豆杉和云南红豆杉次之,东北红豆杉和中国红豆杉相对较弱。应加强红豆杉在城市园林绿化中的应用研究,以充分发挥红豆杉的生态效益。