A WWW Based CAI Environment

A CAI environment based on WWW is described and its advantages and feasibility are discussed. Also a set of functions of this CAI system and a set of tools of courseware authoring and system supervising are designed.     

城市木材工业走在可持续发展道路中

城市木材工业是城市林业的组成部分。在发展城市林业的木材工业生产时,要遵守森林资源的综合利用与环境保护相协调,要特森林资源节约放在首位。因此,在发展城市木材工业生产过程中,推行减量化、回收利用、再循环、重组合、代用品、重现性、重整修、再生产等一系列措施,使城市木材工业稳步地可持续发展。     

Heterosis in inter and intrasubspecific crosses over three-environments in rice

Moderate to high heterosis for yield and ten related characters was studied in 45 crosses involving six indica (I) and four tropical japonica (J) varieties of rice under three (E₁-optimum sowing and high fertility, E₂-both optimum sowing and fertility and E₃- late sowing and high fertility) environments. Trends of magnitude of heterosis for grain yield and plant height were I/J > I/I > J/J and for days to 50% flowering I/J > J/J > I/I hybrids. Estimates of standard heterosis (%) for grain yield were –64.5 to 146.1 in E₁, –70.4 to 82.2 in E₂ and –67.2 to 63.8 in E₃. Environment E₁ seemed to be more favorable for higher heterosis expression than others. Higher heterosis in yield also accompanied heterosis in panicle number, dry matter and spikelet and grain number per panicle. Most estimates for days to flower were negative. Heterotic I/J hybrids also recorded maximum heterosis for earliness. Moderate to low standard heterosis for plant height across environments (2.0 to 13.7%) was recorded. Hybrids were identified in specific environments for direct exploitation in hybrid breeding. Hybrids B4116 / Sarjoo 52, B4122 / Pant Dhan 4 and B4122 / Narendera 359 were more stable than others over three environments. This revised version was published online in July 2006 with corrections to the Cover Date.     

A mixed model analysis of 10 years of oat evaluation data: use of agronomic information to explain genotype by environment interaction

The versatility of mixed model procedures in investigating large, unbalanced sets of genotype by environment data is illustrated on an historic set of yields from a South Australian oat evaluation program. Information on specific genotypic traits is included in the analysis in order to isolate unexplained genotype by environment interaction.     

Repeatability of different stability parameters for grain yield in chickpea

The presence of genotype × environment (GE) interactions in plant breeding experiments has led to the development of several stability parameters in the past few decades. The present study investigated the repeatability of these parameters for 16 chickpea (Cicer arietinum L.) genotypes by correlating their estimates obtained from extreme subsets of environments within a year and also over years. Based on the estimates of response and stability parameters within each trial, the ranking of genotypes in the low-yielding subset differed from that in the high-yielding subset. This indicates poor repeatability for response and stability parameters over the extreme environmental subsets. The estimates of mean yield and stability parameters represented by ecovalence, W²_i, were consistent over years, whereas those of response parameters (b_i, and S²_i) showed poor repeatability. Our results suggest that single-year results for yield and stability can be used effectively for selecting cultivars with stable grain yield if tested in a wider range of environments.     

森林覆盖与生态环境

森林与人类生存息息相关。发展林业,是我国的一项基本国策。发达的林业是国家富强、民族繁荣、社会文明进步的重要标志之一,是发展国民经济、保障农业生产、防止自然灾害、美化环境。增进人们健康,功在千秋的一件大事。     

纸坊沟流域人工刺槐林生长状况与土壤水分条件研究

本文对安塞纸坊沟小流域不同土地类型刺槐林生长状况进行了分析、并且分析了林地水分生态环境对刺槐生长的影响。分析结果认为,该流域水土流失严重,刺槐应营造水土保持林为主,但在水分条件较好的沟谷地和沟坡地可营造部分用材林,以解决当地木林短缺的矛盾;同时,应加强林地的管理,提高土壤水分的利用率。     

神府─东胜煤田开发区建设对植被影响的调查

文中论述了神府一东胜矿区植被现状及其开矿过程中引起的环境因素变化对植被的影响作用,通过资料分析,认为近期内不会导致植被大面积死亡,而使土地沙化.但是,确实存在着由于植被破坏而引起土地沙化的潜在威胁,应当引起人们的密切关注,作者建议应在神府东胜矿区进一步开展植被建造的系统研究及其演变的系统研究.     

骊山风景区旅游环境资源分析

本文评述了骊山风景区旅游环境资源的现状及其特点,分析影响旅游环境质量的各种因素,提出了保护骊山风景区旅游环境资源的措施     

扁蓿豆光合生态特性的研究

本文在不同天气条件下研究扁蓿豆(Melilotoides ruthenica)的光合-光,光合-温和光合-湿的关系,种群光合的日变化以及灌水对种群光合生态特性的影响。结果如下:1.在一般天气条件下,扁蓿豆种群光合的日变化属于中午降低类型。下午的高峰值比上午低64%。在不同天气条件下日变化类型有所变化。在阴天或晴天灌水后,种群光合速率则无中午降低现象。2.在上午高峰值以前和下午高峰值以后,种群光合速率主受光照强度和温度的影响,随着光强和温度的升降而增减。而在中午前后虽然光照强度和温度较高,但光合速率反而下降,其主要原因是湿度减小所致。在不同天气条件下,种群光合速率的变化幅度有所区别,以阴天的斜率较大。3.扁蓿豆种群的光饱和点较低。阴天的比晴天高40%左右。上午的光合量比下午高105%。4.灌水可提高种群目光合量的56.52%,使光合日变化类型由双峰变为单峰曲线。根据以上光合生态特性,可以认为扁信是属于C₃阴性植物,并为其作为优良的野生混植材料提供可靠的依据。