Genotypic differences in leaf water potential abscisic acid and proline concentrations in spring wheat triticum aestivum during drought stress

Quarrie, S.A.

Annals of Botany 46(4): 383-394


ISSN/ISBN: 0305-7364
Accession: 005520523

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Recent work with spring wheat has revealed significant genotypic variation in changes of H2O potential and abscisic acid (ABA) concentration in response to drought. Two experiments with 8 spring wheat genotypes have been carried out to check the earlier work on relationships between H2O potential and ABA concentration and to examine causes of genotypic variation in the rate of decline of H2O potential during drought. Changes in proline concentration were studied. Plants were grown in controlled environment cabinets with nutrient solution culture and were stressed by withholding H2O as the 5th or 6th leaf on the main stem emerged. Plants were harvested 4, 5 and 6 days after the treatment commenced and measurements of leaf H2O potential, stomatal conductance, ABA and proline concentrations and tissue dry weights were taken. Significant genotypic variation was found in the decrease of H2O potential with time and in the slopes of linear regressions of ABA concentration on H2O potential, confirming earlier results. When differences between leaf areas at the start of the treatment were minimized by varying the genotype sowing date, significant genotypic variation in H2O potentials at harvest was still obtained. The change in H2O potential was significantly positively correlated with shoot: root dry weight ratios at harvest and pre-treatment stomatal conductances. Proline concentrations were significantly correlated with H2O potential for every genotype, although there was no clear evidence of genotypic variation in proline concentrations at a given H2O potential. The possible role of ABA concentration in drought resistance of cereals is discussed.