OSMOTIC ADJUSTMENT IN SORGHUM .1. MECHANISMS OF DIURNAL OSMOTIC POTENTIAL CHANGES

被引:87
作者
GIRMA, FS [1 ]
KRIEG, DR [1 ]
机构
[1] TEXAS TECH UNIV,DEPT AGRON HORT & ENTOMOL,LUBBOCK,TX 79409
关键词
D O I
10.1104/pp.99.2.577
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
Osmotic adjustment, defined as a lowering of osmotic potential (psi(pi)) due to net solute accumulation in response to water stress, has been considered to be a beneficial drought tolerance mechanism in some crop species. The objective of this experiment was to determine the relative contribution of passive versus active mechanisms involved in diurnal psi(pi) changes in sorghum (Sorghum bicolor L. Moench) leaf tissue in response to water stress. A single sorghum hybrid (cv ATx623 x RTx430) was grown in the field under variable water supplies. Water potential, DELTA-psi(pi)], and relative water content were measured diurnally on expanding and the uppermost fully expanded leaves before flowering and on fully expanded leaves during the grain-filling period. Diurnal changes in total osmotic potential (DELTA-psi(pi)) in response to water stress was 1.1 megapascals before flowering and 1.4 megapascals during grain filling in comparison with 0.53 megapascal under well-watered conditions. Under water-stressed conditions, passive concentration of solutes associated with dehydration accounted for 50% (0.55 megapascal) of the diurnal DELTA-psi(pi) before flowering and 47% (0.66 megapascal) of the change during grain filling. Net solute accumulation accounted for 42% (0.46 megapascal) of the diurnal DELTA-psi(pi) before flowering and 45% (0.63 megapascal) of the change during grain filling in water-stressed leaves. The relative contribution of changes in nonosmotic volume (decreased turgid weight/dry weight) to diurnal DELTA-psi(pi) was less than 8% at either growth stages. Water stress did not affect leaf tissue elasticity or partitioning of water between the symplasm and apoplasm.
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页码:577 / 582
页数:6
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