Exogenous Application Of Substances Improves The Drought Tolerance Of Bermudagrass

Bermudagrass（Cynodon dactylon） is one of the widely used lawn grass. Drought is the most serious abiotic stress that affects the plant growth and development. In this study, we developed different methods to increase bermudagrass tolerance to drought stress. First, we applied potassium polyacrylate （K-PAM） with soil and tested the effect on drought tolerance of bermudagrass. Second, we mixed plant hormone, ion and osmolyte and screened a formula which was effective to increase drought tolerance of bermudagrass. The main conclusions were as following:1. In contrast with the control, application of 1% K-PAM effectively increased soil water content and improved bermudagrass growth under drought stress condition. Bermudagrass grown into K-PAM mixed soil showed increased survival rate of bermudagrass and decreased cell membrane damage. Under drought conditions, the K-PAM application significantly increased the protein and proline contents, decreased contents of H₂O₂ and MDA and deduced the production of reactive oxygen species compared with the control. Meanwhile, expression levels of SOD, POD, OSMOTIN and SULFUR E2 in K-PAM treated plants were lower than those in the control group. The results indicated that after the K-PAM treatment increased soil water content and reduced the stress damage on bermudagrass.2. Based on orthogonal design, we screened a formula P7 with mixed plant hormone, ion, and osmolytes. Application of formula P7 slightly inhibited the growth of bermudagrass under control condition. However, foliar application of P7 reduced the contents of EL, MDA and H₂O₂ and the production of reactive oxygen species reduced, but increased the contents of the protein and proline. Bermudagrass with P7 treatment showed significantly higher fresh weight and survival rate, indicating P7 was effective to increase drought tolerance on bermudagrass.3. Compared with the control group, the formula P7 treatment significantly improved the drought resistance on Arabidopsis and rice. Foliar application of P7 decreased EL content, but increased the survival rate notably.This study suggested that either treatment with K-PAM or P7 significantly improved the bermudagrass’ drought tolerance through modulation of ROS and metabolites. This study provided theoretic fundament for the application of exogenous substances that could improve the plant drought tolerance, which will be helpful for extending the plant green period and increasing the plant abiotic stress tolerance.