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Responses of shoot growth and survival to water stress gradient in diploid and tetraploid populations of Lolium multiflorum and L. perenne
Author(s) -
Sugiyama Shuichi
Publication year - 2006
Publication title -
grassland science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.388
H-Index - 19
eISSN - 1744-697X
pISSN - 1744-6961
DOI - 10.1111/j.1744-697x.2006.00062.x
Subject(s) - lolium perenne , shoot , perennial plant , lolium multiflorum , dehydration , biology , cultivar , agronomy , ploidy , horticulture , peg ratio , biomass (ecology) , botany , biochemistry , gene , finance , economics
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.