Selection for drought tolerance base on root characters and anti-oxidative enzymes in tall fescue

This research was conducted to evaluate the effect of mild and intense drought stresses on root traits and some anti-oxidative enzymes and to identify drought tolerant genotypes in tall fescue. Twenty-four genotypes were assessed under three levels of moisture regime (control, mild and intense drought stresses) according to a factorial experiment based on a completely randomized design with three replications. The genotypes were clonally propagated and planted in PVC tubes (60×16 cm). Results indicated that the effect of moisture regime, genotype and their interaction were significant for all of the measured traits. Under mild and intense drought stress, the root length, root dry weight and dry forage yield decreased compared with control. Intense drought stress increased the root/shoot ratio about 25 percent. The activities of catalase and ascorbate peroxidase decreased under intense drought stress compared with control and mild drought stress, while the activity of peroxidase increased in this level of stress. Results showed that some tall fescue genotypes under drought stress had high yield productivity, desirable root and anti-oxidative systems indicating that these genotypes had drought avoidance and drought tolerance mechanisms which can be used for future breeding programs.