Constitutive water-conserving mechanisms are correlated with the terminal drought tolerance of pearl millet [Pennisetum glaucum (L.) R. Br.]
Abstract
This study investigates the terminal drought tolerance of pearl millet. Two pairs of tolerant/sensitive pearl millet genotypes and NILs were tested.
Upon exposure to water deficit, transpiration began to decline at lower fractions of transpirable soil water in tolerant than in sensitive genotypes, and NILs-QTL followed the pattern of the tolerant parents. The transpiration rate (Tr) under well-watered conditions was lower in tolerant parents, and the Tr of NILs-QTL followed the pattern of the tolerant parents.
In addition, Tr measured in detached leaves from field-grown plants showed lower Tr values in tolerant parents. Defoliation led to an increase in Tr that was higher in sensitive genotypes.
The differences in Tr between genotypes was not related to the stomatal density. These results demonstrate that constitutive traits controlling leaf water loss under well-watered conditions correlate with the terminal drought tolerance.
Such traits may lead to more water being available for grain filling.