Moisture and Temperature Effects on Emergence and Initial Growth of Two Range Grasses1

Abstract

AbstractThis research, conducted in controlled light‐temperature chambers, studied the effects of two temperature regimes and five moisture levels on early growth of black grama (Bouteloua eriopoda (Torr.) Torr.) and boer lovegrass (Eragrostis chloromelas Steud.). The maximum daily soil temperatures ranged from 53 to 67C in the high temperature regime, and from 38 to 51 C in the low temperature regime, depending on moisture level. The daily minimum temperatures were about 25C in all treatments. The five soil moisture levels were determined as a portion of the volume required to maintain field capacity conditions. Level A was approximately field capacity; levels B and C were watered as level A on the planting day, and then reduced to about a half and a third of level A for the remainder of the 21‐day trial. Levels D and E were watered as level A for the first 3 days, and then reduced to about a half and a third of level A for the remainder of the trial.In the high temperature regime black grama did not emerge at moisture levels B and C; and boer lovegrass did not emerge at levels B, C, and E. In addition, boer lovegrass did not emerge in the low temperature regime at moisture level C. Survival of emerging seedlings ranged from 0 to 4.7% in the high temperature regime at all moisture levels except A. Reduced soil moisture, a day after planting, was more detrimental to survival than reducing soil moisture the third day after planting. Survival of black grama at moisture level A in the high temperature regime was not adversely affected by the high leaf temperatures (81C). The shoot lengths and weights of surviving black grama seedlings were always greater than those of boer lovegrass. Survival and growth of seeded species in the Southwest would be enhanced if soil temperatures and evaporation from the soil surface were reduced. Under the conditions of this 21‐day trial it took about 70 mm of water for either species to survive in the low temperature regime and about 231 mm to survive in the high temperature regime