Variety tolerance to drought in Kentucky bluegrass

Abstract

The relative drought tolerance of 25 Kentucky bluegrasses were studied by examining seedlings and mature plants in the field and greenhouse. The anatomy and morphology of representative varieties were studied relative to drought tolerance. The varieties were tested under field conditions and the "common types" were shown to be the more drought tolerant. Code 95, a common type, and Merion exhibited excellent drought tolerance and produced turf with good color, texture and density. Turf mowed at 1 1/2 inches was more tolerant to drought than turf maintained at 3/4 inch. Seedlings of ten varieties were subjected to drought stress. The primary purpose of this study was to determine the length of time seedlings could survive between irrigations. The study indicated that drought tolerance for mature turfgrass could not be adequately determined from seedlings. Maturity and rhizome development of Kentucky bluegrass were correlated with drought tolerance. To obtain supportive data for field findings, drought work was repeated under greenhouse conditions. Contradictive data was obtained due to environmental differences in the greenhouse. Several varieties, however, responded similarly in both field and greenhouse. It was concluded that Code 95, Merion and Geary, a common type, required less water to produce quality turf. Windsor and Pennstar did not satisfactorily tolerate drought stress in either the greenhouse or field. The morphology and anatomy, as related to drought, was investigated. The purpose was to determine what structural adaptations, if any, may be responsible for postponing internal moisture stress. Drought tolerant varieties were shown to be relatively more rapid growing, to have many, small stomata on the upper leaf surface and fewer and relatively larger stomata on the lower leaf surface, bulliform cells of greater length, closely oriented vascular bundles, smaller metaxylem vessels, and an absence of thick walled sclerenchyma fiber development.