Response of three dominant forages to drought stress at different growth stages

To quantitatively evaluate the effects of different levels of drought stress on the morphological characteristics and drought resistance of three dominant grass species at different growth stages, field drought stress experiments, membership functions, and fixed-point real-time observations were carried out in the Songnen grassland. The results showed that, at the same growth stage, the higher the degree of drought, the greater the influence of drought stress on plant height, leaf length, chlorophyll content, and yield. Consequently, the morphological characteristics of the three types of forage were most seriously affected under extreme drought stress. Under steady drought stress conditions, the plant height, leaf length, chlorophyll content, and yield gradually decreased with growth stage, and the morphological characteristics of all three types of forage were most seriously affected in the turning green stage. When both the growth stage and drought grade were superimposed, a synergistic effect on the morphological characteristics of all three forages was observed. The drought resistance of the forages during their growth periods showed a certain trend. All three showed their strongest responses at the flowering stage. However, while Leymus chinensis and Kalimeris integrifolia had a stronger response to drought stress during the turning green stage than at the heading stage, Artemisia anethifolia showed a higher resistance during the heading stage than at the turning green stage. The results of this study may be used as a guide when planning for contingencies involving drought stress faced by grasses at different growth stages. It may also provide a reference for cultivating excellent drought-tolerant grass species and for the sustainable development of grassland ecosystems.