Classification of Erythrina provenances by rumen degradation characteristics of dry matter and nitrogen

Some species of the genus Erythrina have considerable potential as forage, but information on their nutritional value is scanty. The objective of the study was to define groups of Erythrina provenances based on rumen degradation parameters for dry matter and nitrogen which would be useful in the selection of provenances for detailed nutritional or tree improvement studies. Degradation parameters (i.e. soluble fraction (a), slowly degradable fraction (b), rate of degradation (c) and extent of degradation (a + b) were estimated for twenty Erythrina provenances belonging to seven species (E. abyssinica, E. bentipoeme, E. brucei, E. burana, E. melanacantha, E. poeppigiana and E. variegata)). The data were subjected to principal component and cluster analyses for grouping, and the 20 provenances were placed into four distinct cluster groups. Provenances of E. brucei and E. abyssinica belonged to three clusters, whereas provenances of E. burana and E. variegata were confined to one cluster. Using extent of dry matter and nitrogen degradation values of 71 and 86% respectively, as a forage quality index, members of clusters 1 and 2 (i.e. E. abyssinica, ILCA 10606; E. brucei, ILCA 10579, 10625, 10628, 10637, 10643; E. burana 10575, 10641, 12157; E. melanacantha ILCA 10574 and E. variegata ILCA 14991 and 14994), appeared to be superior in quality to their counterparts in clusters 3 and 4. The results suggested existence of intra and inter-species variation in rumen degradation characteristics for dry matter and nitrogen within the genus Erythrina.     

皇藏峪国家自然保护区青檀种群年龄结构及种内、种间竞争

青檀(Pteroceltis tatarinowii)是一种具有重要经济和保护价值的树种。本文研究了安徽省皇藏峪国家级自然保护区青檀种群的年龄结构,并利用Hegyi单木竞争指数模型研究该地区青檀的种内、种间关系。结果表明:皇藏峪自然保护区青檀种内、种间竞争关系最合适的样圆半径为8m。保护区青檀种间竞争指数占青檀所受总竞争指数的71.79%,种内竞争指数占28.21%,该地区青檀所受的竞争压力主要来自于种间;不同竞争木的竞争指数表明:使青檀受压的主要植物是栓皮栎和黄连木。受压最大的青檀是胸径在2～5cm的小树,而随着青檀径级的增大,植株所受竞争强度逐渐减小,竞争强度与胸径的关系服从幂函数关系。根据幂函数模型预测,在青檀胸径达15cm之前,受到的竞争压力较大,此后,竞争压力变小。     

落叶松种间及种内和种间杂种家系间的物候变异与早期选择

对造林后1～3年生7种(变种)落叶松和7个种内和种间杂种家系的9个物候期进行连续定株观察及生长量调查,利用方差分析方法研究落叶松种间、家系间物候期的变异,利用主成分分析方法划分落叶松种(家系)的物候群,利用典型相关分析方法确定物候期与幼林生长量之间的关系.结果表明:除侧枝芽膨大外,落叶松种间、家系间各物候期的变异均达极显著水平.同样,种内个体间、家系内个体间也存在一定的物候期变异,但同种家系内个体间的变异明显小于杂种家系内个体间的变异.兴安落叶松顶芽展叶、抽新梢时间明显早于其他种,封顶也最早;其次是长白落叶松和华北落叶松;朝鲜落叶松和欧洲落叶松的封顶时间比长白和华北落叶松还要迟半个月;日本落叶松顶芽膨大和展叶时间最晚,封顶时间也明显迟于其他种.以日本落叶松为母本的各种间杂种,在物候上多数表现出中间偏母本的特性,而在抗病能力方面较父本有所改善,在抗寒性方面却明显优于母本.日本落叶松生长最快,其次是长白和朝鲜落叶松,而日×长、日×兴杂种生长量超过母本,表现出超亲杂种优势,表明在东北地区落叶松杂种利用潜力巨大.根据主成分聚类结果,可将14份遗传材料分为4个物候型.除侧枝芽开始展叶、完全展叶和抽新梢以外的其他物候因子与生长量之间相关紧密.物候因子对生长量有相当好的预测能力,即顶芽萌动、展叶越早,封顶越迟,生长期越长,对树木的生长越有利.     

基于SRAP标记研究石竹属植物遗传多样性

石竹属花卉植物花色艳丽，有较高观赏价值，且具有较强耐逆性，是极为宝贵的基因资源。为从分子水平探究石竹属花卉种质的遗传多样性，利用SRAP分子标记构建了44份石竹属花卉种质的指纹图谱。经遗传多样性分析，44份石竹属花卉被划分为五大类群，与物种分类结果一致；种内分类结果也与花色、株型等指标分类结果相符。物种差异是石竹属植物类群划分的主要因素，种内划分则以花色、株型等指标为主。通过SRAP分子标记可以有效地区分石竹属花卉种质，为石竹属花卉种质资源鉴定与保护、育种应用和分子机理研究提供了技术支撑和理论基础。