THE RELATION BETWEEN RESPIRATION AND GROWTH-RATES OF ACCESSIONS OF PLANTS OF THE GREAT-BASIN, UNITED-STATES

Native plants used for revegetation must be able to grow and become es tablished rapidly, whether transplanted as seedlings or directly seede d. Quick methods for predicting performance and identifying genotypes for a given environment are needed to improve revegetation success. Da rk respiration rates measured in field and laboratory by microcalorime try, infrared gas analysis, or oxygen electrodes are proposed as means for identifying plants for revegetation projects. Several accessions of Achillea millefolium, Artemisia tridentata, Bromus tectorum, Poa se cunda, and Stipa thurberiana were collected from different locations a nd grown in common gardens. Growth was measured as linear extension gr owth and/or increase in dry weight per unit time. In some cases, visua l estimates of chlorophyll content and wet-dry weights were used as an index of viability-particularly in an extended drought. Differences i n metabolism were correlated with differences in the environment of or igin. For example, Poa secunda from dry sites was metabolically distin ct from Poa secunda from more mesic sites, even when both were grown i n common gardens. Young leaves differed from fully expanded leaves in both metabolic rate and pathways, Metabolism is greatly affected by en vironmental factors such as temperature, light intensity, drought, sal t, heavy metals, air pollution, etc., but still predicts growth at ext ant conditions. Growth rate predictions based on metabolic rate measur ements generally agreed with predictions based on C-13/C-12 ratios, bu t respiration rate measurements are faster and less expensive than iso topic ratios and are applicable to C-4 as well as C-3 plants.