Influence of Intact Tillers and Height of Stubble on Growth Responses of Tall Fescue (Festuca arundinacea Schreb.)1

Abstract

Complete defoliation of tall fescue (Festuca arundinacea Schreb.) seldom occurs under good grazing management. In this study, the influence of defoliation on the growth response of tall fescue plants was examined. Vegetatively propagated Kentucky 31 tall fescue plants, grown in the greenhouse, were cut back to a stubble height of 1, 21/2 or 4 inches in a factorial combination of leaving 0, 10%, 20%, or 30% intact (uncut) tillers. Increased tillering, greater daily and total regrowth yields of dry matter, and higher levels of food reserves resulted from increasing the height of stubble or from leaving intact tillers. Generally the influence of intact tillers, especially on rate of growth, decreased as the stubble height was increased. Plants completely defoliated to a 1‐inch stubble (1 inch‐0%) died within 32 days after the initial harvest, and there was a marked decrease in rate of recovery with each successive harvest of the 21/2 inches‐0% treatment. Within a stubble height, little change in tillering or regrowth yield resulted from leaving more than 10% intact tillers, but food reserves increased with each addition of intact tillers. Apparently 10% or more intact tillers or a 4‐inch stubble provide adequate photosynthate production and food reserve storage for plant survival and growth under conditions of defoliation stress.