Differences in the physiological responses of female and male Buchloe dactyloides plants to drought stress

Buffalo grass is a rare dioecious turfgrass. Analyzing differences in drought resistance between male and female buffalo grass provides a theoretical basis for the study of physiological differences in dioecious plants. In this study, buffalo grass of the 'Texoka' variety (Buchloe dactyloides) was used as the experimental material, and cloned branches of female and male plants were used for cutting propagation. Three drought stress treatments were applied after flat formation: normal watering/control (field water capacity, 90%, CK); semi-drought (field water capacity, 50%, H); and drought (field water capacity, 30%, D). The results showed that the plant height, biomass, root-shoot ratio, leaf relative water content, and chlorophyll fluorescence parameters of female and male B. dactyloides did not change significantly with increasing drought severity. Malondialdehyde (MDA) and proline (PRO) contents in female plants were significantly higher than those in male plants, and were positively correlated with the degree of drought. Superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) activities differed significantly between female and male buffalo grass plants. In addition, the antioxidant enzyme activity of B. dactyloides was significantly higher in female plants than that in male plants under the same drought conditions; therefore, the ability to remove reactive oxygen species (ROS) is stronger in female plants than that in male plants. Consistent with these findings, two-factor and principal component analyses showed significant differences in the responses of male and female B. dactyloides plants to drought stress. Membership function analysis showed that the drought resistance of female buffalo grass was higher than that of male buffalo grass. In conclusion, our findings confirm that phenotypic gender differences impact the physiological responses of B. dactyloides to drought stress, with females displaying stronger drought resistance than that of their male counterparts under the same conditions.