水稳砂砾沥青路面冷再生材料温缩和抗冻性能试验研究

水泥稳定冷再生材料属于半刚性材料,其以强度高、刚度大、路用性能好等优点,在实际工程中得到广泛的应用。但是半刚性基层材料也存在着如抗裂性能和抗冻性能差等缺陷。因此抗裂性能和抗冻性能是半刚性基层亟待解决的问题。本文以不同的水泥剂量、沥青面层与半刚性基层厚度比,以及不同新骨料掺加量的冷再生材料进行温度收缩系数试验和抗冻性能试验研究,得到不同配合比例与水泥稳定冷再生材料不同龄期的温度收缩系数和耐冻系数之间的关系。     

Marker trait association for autumn cold acclimation and growth rhythm in pinus sylvestris

The main objective of this study was to identify quantitative trait loci (QTLs) involved in the genetic control of growth rhythm and autumn cold acclimation in Pinus sylvestris L. Eighteen full‐sib families of P. sylvestris with parental origins between latitudes 62 and 67° N in Sweden were assessed for autumn cold acclimation (frost injury measured from artificial freeze testing) and growth rhythm during the first two growing seasons. One family north × south with 108 individuals was used for the construction of one linkage map for the male and one for the female parent using 286 markers from random amplification of polymorphic DNA. Marker trait associations (QTLs) for shoot elongation, growth cessation and cold acclimation were found on both maps. Some QTLs were verified in two additional north × south families. Proportions of the additive genetic variance explained by the markers (R ²/_G) indicated that genetic factors of large effect were involved in all investigated traits. Single or multiple markers accounted for between 16 and 47% of the additive variance in annual shoot elongation, between 42 and 79% of the additive variance in growth termination, and between 7 and 31% of the additive variation in autumn cold acclimation. The study confirms that there are major QTL regions on different linkage groups controlling a large part of the variation for growth rhythm and autumn cold acclimation in P. sylvestris.     

Growing fruit trees in highly alkali soils—a case study

The performance of 10 fruit species, namely pomegranate (Punica granatum), guava (Psidium guajava), sapota (Achras japota), baelpather (Aegle marmelos), amla (Emblica officinalis), ber (Zizyphus mauritiana), karaunda (Carissa carandas), date palm (Phoenix dactyleform), jamun (Syzygium cuminii) and imli (Tamarindus indica), as affected by site preparation and amendment use, was evaluated in a replicated field trial established in 1992 in a highly alkali soil (pH 10·5) at the Bichhian experimental farm of the Central Soil Salinity Research Institute, Karnal. The treatments involved two site preparation methods: (1) augerholes of 20–25 cm diameter and 160–180 cm deep made in the centre of 45 cm×45 cm pits in the main plot and (2) pits of 90 cm×90 cm×90 cm; variable amendments composition in the subplot and fruit species in the sub-subplots. Growth observations recorded 26 months after planting showed that survival, height and girth of all species remained unaffected owing to site preparation techniques and amendment use. Irrespective of planting techniques and amendment use, jamun, guava, ber and imli performed best. Date palm and baelpather performed poorly. Initial growth of sapota was satisfactory, but it was found highly sensitive to frost. Similarly, pomegranate which was performing exceedingly well was found very sensitive to prolonged water stagnation. This 3-year study indicated that out of 10 species tried, about half a dozen fruit plants can be established in alkali soils after following appropriate site preparation methods and better management practices. Established species came to bearing between 18 and 24 months after planting, but the fruits were damaged by prolonged water stagnation during the monsoon season and chilling temperatures of the 1994–95 winter. This study further indicated that the augerhole method of root bed preparation, is an economical, less laborious and faster way of planting fruit trees than is the pit method. The experiment will be continued to study treatment effects on fruit production and quality before making final recommendations. © 1997 John Wiley & Sons, Ltd.     

Breeding intensive winter bread wheat varieties for Southern Ukraine

Winter wheats with high grain quality for bread making are produced in southern Ukraine. Wheat breeding began more then 80 years ago. Over this time, seven wheat variety changes were made and yield potential increased from 2.73 t ha^-1 to 6.74 t ha^-1. This increase was due to a decrease in photoperiodic sensitivity and the introduction of semidwarf genes. Genes for photoperiodic sensitivity (Ppd) and vernalisation requirement (Vrn) were combined, and the effect of these genes on grain yield, frost and drought resistance, and growth and development rate of plants in autumn and early spring were studied. Breeding was carried out, utilising traditional and non-traditional methods such as anther culture, biochemical and molecular markers, and screening in artificial environments using phytotrons. This approach resulted in the release of several winter wheat varieties with high yield potentials and well expressed adaptation features by the Plant Breeding and Genetics Institute (Odessa). This revised version was published online in August 2006 with corrections to the Cover Date.     

核桃新品种‘晋黎’

核桃新品种‘晋黎’来源于山西省黎城县核桃园中发现的优良单株。平均单果质量17.2 g,壳厚1.26 mm,出仁率59.7%。嫁接第2年挂果,盛果期平均株产坚果12 ~ 15 kg。遭遇晚霜危害后副芽萌发形成新梢,仍能正常开花结实。     

白于山山区大扁杏生产中的问题分析

陕北白于山山区以大扁杏为主开展了仁用杏基地建设,但大扁杏开花不结果,经济效益差.通过多年的调查和监测认为该区大扁杏生产中存在的主要问题是花期、幼果期霜冻频繁且强度较重,易冻花冻果;选择的主栽品种为龙王帽,树体生长量小,开花早且花期短,不抗霜冻;大多数杏园建立在南坡坡地上,培育的树形以开心形为主,树体的结果部位较低,选留的结果枝为花束状果枝和短果枝,开花早、花期短且集中,不易躲避霜冻等.建议该区积极选育开花晚、抗霜冻的大扁杏品种,加强栽培管理,同时建立以山杏为主的仁用杏生产基地.     

杨树苗圃冬灌防寒效果研究

本研究用对比实验的方法,测试苗圃地冬灌后的苗木枯梢率、苗木含水率、土壤含水率、苗木相对电导率,以检测杨树苗圃冬灌防寒效果。结果表明:冬灌对一年生沙兰杨苗木越冬含水率变化没有影响;对一年生辽宁杨苗木含水率有所提高;对一年生3016杨苗木含水率没有影响;冬灌能有效提高苗圃地内土壤含水率;冬灌能够明显降低苗圃地内苗木越冬时期的相对电导率,能够在一定程度上提高苗木的抗冻性。     

森林低温霜冻灾害干扰研究综述

在全球变暖的背景下,森林低温霜冻灾害的发生并没有减少趋势,低温霜冻灾害的发生可能对林木的组织或整个幼树、幼苗产生致命伤害,进而成为林木生长发育,天然或人工更新的一个主要限制因子.森林低温霜冻灾害的发生和危害程度取决于林木生长复杂多变的物理环境和树木的耐冻性,前者又受大尺度环流形势及局地尺度小气候特征的影响.借助于3S技术建立复杂地形下低温和光照的空间分布模型,并结合林木的耐冻性,构建低温霜冻危害评估的概率模型,将有助于提高霜冻灾害的监测和危害评估水平.森林低温霜冻的防御应考虑将物理与生物防霜方法相结合,前者通过建防护林和采取合适的采伐措施,来改善林内地表的辐射平衡;后者则通过生物技术手段来增强林木的耐冻性.需结合霜冻灾害的监测和危害评估模型,对各种不同防霜措施的防霜效果进行定量评估.     

宁夏2014年苹果晚霜冻害调查分析

苹果是易受霜冻影响的经济林果之一,2014年春季宁夏冷空气频发,出现多次霜冻天气过程,为了了解2014年晚霜冻对宁夏苹果的综合影响,文章运用调查和统计方法,分析了宁夏苹果遭受晚霜冻危害情况。结果表明,2014年宁夏苹果花期和幼果期均遭受霜冻危害,平均综合危害程度在30%~35%;综合晚霜冻危害受日最低气温出现次数和阶段内极端日最低气温影响较大;各地差异明显,从有限调查点来看,中宁轿子山林场受冻较为严重;不同品种之间,富士受冻最严重。文章的调查分析结果有助于进一步把握宁夏苹果产业受霜冻危害的潜在危险性。     

冰核活性细菌的分子生物学及防霜技术的研究进展

 从冰核活性细菌的分子生物学基础上,研究冰核细菌的基因遗传背景。并提出了冰核细菌的研究方法,防霜新技术的开发应用及冰核细菌在不同领域的应用等方面阐述冰核活性细菌的研究进展。