Evaluation of Tall Fescue Germplasms for Drought Tolerance.

Abstract:

Drought is the single most constraint for the production of cool-season perennial grasses in the south-central USA. Persistence of tall fescue, an import forage grass, is significantly affected by the hot and dry weather that prevails in the region. Developing drought tolerant cultivars is an important goal of our tall fescue breeding program. Tall fescue germplasms from Germplasm Resources Information Network (GRIN) have been screened for drought tolerance in a replicated greenhouse experiment. Data on chlorophyll content, plant vigor, leaf rolling, root penetration and osmotic potential have been collected. Several of these measurements have been undertaken at multiple time points. Chlorophyll content is normally distributed in the tall fescue collections and steadily increased during initial drought stress. After 16 days of stresses, molal concentration in the collection varied from 100 -700 mmol kg^-1. Drought stress significantly affected osmolarity of the tall fescue genotypes. We used an index selection procedure giving different weightage to osmotic potential (60%), plant vigor (30%) and chlorophyll content (10%), for determining drought tolerant genotypes from the germplasm collection. Evaluation of the top 50 selected genotypes in replicated field experiment is in progress.