Osmotic adjustment leads to anomalously low estimates of relative water content in wheat and barley

被引:86
作者
Boyer, John S. [1 ,2 ]
James, Richard A. [3 ]
Munns, Rana [3 ]
Condon, Tony A. G. [3 ]
Passioura, John B. [3 ]
机构
[1] Univ Delaware, Coll Marine & Earth Studies, Lewes, DE 19958 USA
[2] Univ Delaware, Coll Agr & Nat Resources, Lewes, DE 19958 USA
[3] CSIRO Plant Ind, Canberra, ACT 2061, Australia
关键词
drought; osmotic potential; relative turgidity; salinity; salt stress; water potential;
D O I
10.1071/FP08157
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
Relative water content (RWC) is used extensively to determine the water status of plants relative to their fully turgid condition. However, plants often adjust osmotically to salinity or water deficit, which maintains turgor pressure and obscures the definition of 'full turgidity'. To explore this problem, turgor was measured by isopiestic psychrometry in mature leaf blades of barley (Hordeum vulgare) and durum wheat (Triticum turgidum ssp. durum) salinised to 150 mM NaCl, or bread wheat (Triticum aestivum) grown in soil dehydrated to varying degrees. Osmotic adjustment maintained turgor in all the plants but despite full maintenance in some of the salinised plants, their leaf RWC decreased substantially. This occurred because excess water was absorbed while the samples were floated on water as part of the RWC measurement. The absorption falsely increased the weight of the 'fully turgid' condition, causing RWC to be anomalously low by 10-15%. Cell solution was secreted into intercellular spaces and was seen under a microscope, which is a test encouraged for all RWC measurements. Several alternate methods are suggested for rehydrating tissues while minimising excess water absorption, but no simple definition of 'full turgidity' seems possible. In general, direct measurements of osmotic adjustment and turgor are preferred.
引用
收藏
页码:1172 / 1182
页数:11
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