权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Effects of drought stress on xylem permeability and transpiration control

干旱胁迫对木质部通透性和蒸腾控制的影响

基本信息

批准号：
16580122
负责人：
YOSHIKAWA Ken
金额：
$ 2.24万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Dieback is observed in drought conditions for many tree species. Xylem structure and hydraulic conductivities were compared between tree species with different dieback incidences, using seedlings of Chamaecyparis obtusa and Juniperus chinensis growing under drought conditions. Leaf specific hydraulic conductivities were constant from the base to the top of the shoots in C. obtusa, whereas those of J. chinensis were higher in the top of the shoots than in the base. It is probable that these species specific hydraulic conductivities cause the differences of dieback incidencesMost of Cupressaceae species have needle leaves and scale leaves in an individual. We investigated the relations between these heterophylly and growing conditions for Cupressaceae species, Sabina vulgaris, growing in semi-arid areas of China, to demonstrate the relations of heterophylly to the stress tolerance. Ratios of needle leaves were much higher than those of scale leaves in the seedlings, which can grow in the moist and shade conditions under the canopies of nurse plants, whereas ratios of scale leaves were greatly higher than those of needle leaves in the large-sized individuals growing under the drought and open sites. It is likely that leaf form varies with the light and soil moisture conditions and the heterophylly permit S. vulgaris to maintain the population in semi-arid areas.We performed a comparison of water balance o ftwo tree species under the different light conditions, with seedlings of Quercus glauca and Eurya japonica. It was observed that water balance significantly varies with the species in the high light intensity, which induces an increase of transpiration rates. It is likely that Q. glauca reduces water loss by low stomatal conductance and small vessel diameters for reduction of cavitation. E. japonica probably reduces the water loss by low stomatal conductance and small amounts of total leaf area

许多树种在干旱条件下都能观察到枯萎。以干旱条件下生长的钝顶杜鹃和杜柏幼苗为材料，比较了不同枯萎发生率树种的木质部结构和导水率。黄连木的叶片比导水率从地上部到地上部基本不变，而地上部的导水率则高于地上部。这可能是由于这些树种的比导水率不同造成的。大多数柏科树种的个体都有针叶和鳞叶。我们研究了生长在中国半干旱地区的柏科植物臭柏的异叶性与生长条件的关系，以论证异叶性与抗逆性的关系。苗木针叶所占比例远高于鳞片，可在苗木冠层下潮湿和阴凉条件下生长，而在干旱和露地条件下生长的大型个体，鳞片所占比例远高于针叶。叶形可能因光照和土壤水分条件的不同而不同，这可能是异叶性使普通落叶松在半干旱地区维持种群的原因之一。我们以青栎和榆树幼苗为材料，比较了两种树种在不同光照条件下的水分平衡。结果表明，在强光强下，不同树种的水分平衡存在显著差异，导致蒸腾速率增加。青冈可能通过降低气孔导度和减少气蚀的导管直径来减少水分损失。结缕草可能通过降低气孔导度和少量的总叶面积减少失水。