Root anatomical, physiological, and morphological responses to drought stress for tall fescue cultivars

Two experiments were conducted to investigate genotypic variations in morphological, anatomical, and physiological responses of roots to drought stress in tall fescue (Festuca arundinacea Schreb.). Such information would facilitate breeding programs and management practices for improving turfgrass drought resistance. Tall fescue cultivars 'Kentucky-31' (forage-type), 'Mustang' (turf-type), and 'MIC18' (dwarf, turf-type) were examined under well-watered or drought-stress conditions in a greenhouse. Root systems of MIC18 were much shallower and smaller than those of Kentucky-31 and Mustang under well-watered conditions. After 7 d of soil drying, root dry weight was significantly lower than that of well-watered plants for both MIC18 than Kentucky-31. The reduction in root dry weight, relative to control plants, was greater for MIC18 than Kentucky-31. Root water potential and turgor pressure were reduced,vith soil drying, leading to cortical cell shrinkage. Kentucky-31 roots suffered less turgor loss than those of MIC18 under drying conditions. Specific root length (SRL) and root/shoot ratio increased with soil drying. Greater increases in SRL occurred for Kentucky-31 than for MIC18. More extensive root hairs developed in plants of Kentucky-31 and MIC18 stressed for 14 d than in well-watered plants. Root hairs became less extensive after 28 d of drying. After 14 and 21 d of drying, Kentucky-31 roots had significantly lower electrolyte leakage than those of MIC18. Cultivar variations in anatomical, morphological, and physiological features of roots accounted for the variability in shoot performance under drought stress noted in a previous study.