Effects of High Temperatures on Emergence and Initial Growth of Range Plants1

Abstract

AbstractThe daily soil temperatures used in this light chamber study were patterned after observations made under field conditions: 18 to 39C where the surface was sparsely shaded by brush, and 18 to 53C where the surface was left bare. The soil moisture was maintained at field capacity. Emergence of sacaton (Sporobolus wrightii Munro), vine mesquite (Panicum obtusum HBK.), bush muhly (Muhlenbergia porteri Scribn.), and fourwing saltbush (Atriplex canescens (Pursh) Nutt.) was adversely affected by the high temperature regime. Survival of all 14 accessions except rhodesgrass (Chloris gayana Kunth), ‘Vaughn’ sideoats grama (Bouteloua curtipendula (Michx.) Torr.), and black grama (B. eriopoda (Torr.) Torr.) was reduced by the high temperature regime.At the close of the 21‐day trial most species had stopped growing or were growing very slowly under the high temperature regime. The shoot weights for the plants growing in the low temperature regime averaged nearly twice as much as those growing in the high temperature regime. There was no significant difference in root weight per seedling between temperature regimes. The root lengths of black grama, ‘Vaughn’ sideoats grama, tobosa (Hilaria mutica (Buckl.) Benth.), lehmann lovegrass (Eragrostis lehmanniana Nees), and alkali sacaton (Sporobolus airoides (Torr.) Torr.) were not reduced significantly by the high temperature regime.The high temperatures were detrimental, in one way or another, to all species even when moisture was adequate but black grama and sideoats grama performed satisfactorily.