Osmotic adjustment in maize: Genetic variation and association with water uptake
1997
Chimenti, C.A. | Cantagallo, J. | Guevara, E.
This paper reports on a study of osmotic adjustment in maize, an attribute linked to tolerance to water stress in some species. The hypotheses tested were: (A) genotypes differ in their capacity for osmotic adjustment; and (B) osmotic adjustment measured in the pre-flowering stage is associated with performance of plants exposed to water stress in the field. Twenty inbred lines were exposed to water stress under semi-controlled conditions during the 4 wk before flowering; stress was initiated at the sixth visible-leaf stage and was followed by a period of gradual drying out of the soil. Changes in water status of the plants were defined in terms of leaf relative water content (RWC) and osmotic potential (Y0). Degree of osmotic adjustment (OA) was expressed as the estimated value of RWC for a defined value of Y0 (taken here as -2 MPa), referred to as RWCe. Thus, a high RWCe indicates a high degree of OA. All genotypes showed some degree of OA. The range of RWCe obtained varied with genotype from 87 Per cent to 58 Per cent, and significant differences (P0.05) in RWCe existed among genotypes. In a second experiment in the field, a subset of the inbred line collection was exposed to water stress 20 d before flowering. Water deficits reduced soil water extraction, dry matter, and yield. Variations in relative changes in these variables across genotypes were associated with variations in the degree of OA exhibited by the genotypes. We conclude that there is a substantial degree of intraspecific variation for OA in maize and that OA may explain some differences in yield observed in the field during water stress. These results suggest that OA estimates could be used to identify drought tolerant genotypes.
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