Responses of shoot growth and survival to water stress gradient in diploid and tetraploid populations of Lolium multiflorum and L. perenne
Responses of shoot growth and survival to water stress gradient in diploid and tetraploid populations of Lolium multiflorum and L. perenne
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DOI：
10.1111/j.1744-697x.2006.00062.x
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发表时间：
2006-12
影响因子：
1.3
通讯作者：
S. Sugiyama
中科院分区：
文献类型：
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作者：
S. Sugiyama
干旱胁迫是决定牧草生长和生存的关键环境因子之一。以意大利黑麦草（Lolium multiflorum）和多年生黑麦草（L. perenne）二倍体和四倍体品种为研究材料，采用含不同浓度聚乙二醇（PEG）的水培体系，研究了不同浓度（0 Mpa、- 0.6 Mpa、- 1.2 Mpa和- 1.8 Mpa）胁迫对植物芽部的响应。由于冻伤是由细胞脱水引起的，因此还研究了两种物种在6种零度以下温度（- 11、- 12、- 14、- 16、- 18和- 20°C）下的冷冻耐受性。在所有胁迫强度下，何首乌草的茎部生物量均大于多年生草，而在严重水分胁迫和冰冻胁迫条件下，何首乌草的存活率均低于多年生草。因此，两种植物的二倍体和四倍体栽培品种在无胁迫条件下的生长潜力与在严重胁迫条件下的存活率之间存在权衡（负相关）关系。这种权衡是由组织含水量介导的。高含水量通过增加比叶面积导致高生长率，而低含水量导致高组织渗透电位，可以赋予高细胞脱水耐受性。
Drought stress is one of the critical environmental factors in determining growth and survival of herbage grasses. In this study, by using a hydroponic culture system including different amounts of polyethylene glycol (PEG), responses of plant shoots to water stress in four different intensities (0 Mpa, −0.6 Mpa, −1.2 Mpa and −1.8 Mpa) were examined in diploid and tetraploid cultivars of Italian ryegrass (Lolium multiflorum) and perennial ryegrass (L. perenne). Since freezing injury is caused by cell dehydration, freezing tolerance was also examined for six subzero temperatures (−11, −12, −14, −16, −18 and −20°C) in both species. L. multiflorum had a larger shoot biomass at all stress intensities and a lower survival rate under severe water stress and freezing stress conditions than L. perenne. Thus, there was a trade-off (negative correlation) between potential growth under a stress-free condition and survival under a severe stress condition in diploid and tetraploid cultivars of both species. This trade-off was mediated by tissue water content. High water content led to a high growth rate through increasing specific leaf area, while low water content resulted in a high tissue osmotic potential that could confer high cell dehydration tolerance.