Effect of Heat Stress on Grain Growth, Starch Synthesis and Protein Synthesis in Grains of Wheat (Triticum aestivum L.) Varieties Differing in Grain Weight Stability

The effect of heat stress on the components of grain weight was analysed in wheat ( Triticum aestivum L.) varieties differing in grain weight stability. The wheat varieties PBW154, Sonalika and Hindi62 were raised in the field (New Delhi, India; 77°12' E, 28°40' N, 228.6 m a.s.l.) at three dates of sowing: 19 November 1992 (DOS I), 14 December 1992 (DOS II) and 18 January 1993 (DOS III). The late-sown crop (DOS III) experienced 6–8 °C warmer temperatures during grain development than the crop sown at the normal time (DOS I). The heat susceptibility index (S) revealed that grain weight was less susceptible to heat in Sonalika and PBW154 than in Hindi62. Heat stress reduced both the grain growth duration (GGD) and the grain growth rate (GGR). The grain weight reduction in PBW154 and Sonalika was mainly due to a reduction in GGR, while that of Hindi62 was due to a reduction in GGD. In vivo studies on starch and protein synthesis in excised endosperm at 15, 25 and 35 °C revealed that both processes were more thermotolerant in Hindi62 than in PBW154. The grain starch content was stable in Hindi62 while that in PBW154 was significantly reduced under heat stress. The grain nitrogen content at maturity increased in both varieties under heat stress. It was concluded that the heat susceptibility of grain weight in Hindi62 was mainly due to a reduction in GGD, although GGR, starch and protein synthesis were more thermotolerant in developing grains of Hindi62 than in those of PBW154.     

樟子松枯梢病的防治研究

樟子松移植苗枯梢病Sphaeropsis sapinea可以通过药剂有效地进行防治。移植前以50％多菌灵wp500倍液浸苗；在人工林中，内吸性杀菌剂－甲基托布津、多菌灵为首选药剂；在树木新梢生长停止期和展叶中期（辽西北为6月初和6月中旬），70％甲基托布津wp 1000倍液或50％多菌灵wp 500倍液防治2次。保护性杀菌剂－百菌清效果不佳。适时的卫生伐对该病有明显的抑制作用。     

白浆土的氮素分布特征

本文以黑龙江省三江平原耕地白浆土为主要研究对象,并以复区内存在的草甸土和暗棕壤作比较,研究了土壤各种理化性质与不同形态氮素之间的相关关系:白浆土中 HA 和 FA 的主要差别,在于前者含有较多的碱性氨基酸,而后者则含有较多的酸性氨基酸;各种不同形状 N素与土壤 pH 值,质地等相关性不显著,而与土壤有机质、全 N 和 C/N 比值等的相关性极为显著。     

Neurotrophins and the Thymus: Morphological Analysis of Mice Carrying a Non-functional Mutation on the Trka and Trkb Genes

Veterinary Research Communications -     

黄皮的生物学特性研究

通过本试验观察表明:黄皮[Clausena Lansium (Lour.)Skeels]的开花与温度有密切关系,温度高,开花过程短;温度低,开花过程长。花穗中的花轴增长速度也随温度升高而加快,花轴增长快,则花轴长,花穗大;反之,花轴增长速度慢,花轴短,花穗小。黄皮开花的顺序是从花穗基部第1—4个分枝开始,每个分枝则先从基部1—8个二次分枝首先开放。31℃是黄皮花粉萌发最适宜温度。在培养基中加入15—20％蔗糖或2.4—D,三十烷醇等生长调节物质,明显可提高黄皮花粉的萌发力。本试验对黄皮的物候期及植物学特性同时进行了研究。     

论城中村农民的现代化改造

针对当前我国城中村改造中存在的一些问题,以系统论为基础,对城中村改造工作的方向和改造工作应遵循的基本原则予以一定的分析,提出城中村改造工作的重点和关键所在是对城中村农民的现代化改造。进一步阐述了城中村农民的现代化改造对于推进城中村改造的重要意义。     

微量元素相对生物学利用率的研究方法

有机微量元素具有多种优点,本文阐述了有关外源微量元素生物学利用率,回顾了微量元素不同添加方法的研究成果并进行比较。1影响动物对微量元素吸收的因素微量元素的吸收水平直接影响动物机体对微量元素的利用。如果饲喂量超过机体的代谢量,微量元素的吸收下降;如果饲喂量不足,机体则会提高对微量元素的吸收,这就说明机体自我平衡作用可以调节营养素的吸收。日粮总体消化率及各营养素间的相互作用均会影响矿物质吸收,这种相互作用包括协同作用(如铁和维生素C)和拮抗作用(如钙和锌,铜和钼、硫)。动物种类、品种、年龄、性别等也会影响微量元…     

小麦品种鄂恩一号和7023生期规律的对比观察与分析

通过对豫南小麦当家品种鄂恩一号和种植多年的7023的对比观察,找出二者在生育规律上的差异,进而分析在栽培措施上的异同。与7023相比,鄂恩一号出叶速度快,容易形成壮苗;抽穗后绿叶保持时间较长,有利后期光合作用;年前分蘖数比例大,总分蘖及成穗数没有7023多;幼穗分化开始早,进程快,小穗数及穗粒数比较少;开花早,灌浆时间长,灌浆强度大,子粒大,千粒重高。基于这些特点,提出了十月下旬播种,三叶期、药隔形成期追肥,四分子期根外喷肥,加强后期管理等针对该品种特性的栽培措施。