Labile and nonlabile energy in blue grama (Bouteloua gracilis) as influenced by temperature, water stress, and fertilizer treatments

Abstract

Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] plants from a native shortgrass prairie were subjected to four treatments at three different temperatures in a growth chamber experiment to evaluate the dynamics of labile and nonlabile energy components in different plant organs. At high temperature regimes (24°/13° and 29.5°/18 °C day–night) blue grama plants accumulated comparatively greater amounts of labile and nonlabile energy in the three organs, viz., shoots, crowns, and roots, than at low temperature regime (13°/7 °C). The labile energy in shoots at the three temperature regimes continued to increase up to a peak value recorded at 90 days and then declined during the subsequent 30-day growth period. On the other hand, the accumulation of labile energy in roots and crowns continued till final harvest. Irrigated plus N-fertilized plants accumulated more labile and nonlabile energy in their shoots than did the irrigated plants, and the latter accumulated more than the fertilized and the control plants. The labile and nonlabile energy components in fertilized plants were at lower levels than the control plants during the 120-day growing period, resulting in net negative energy balance as compared with control plants. Higher temperature, irrigation, and irrigation plus nitrogen application decreased the nonlabile:labile ratios in the plants.