Effects of combined drought and shade stress on morpho-physiological traits and gene expression in Cynodon dactylon along longitude and latitudinal gradients

Currently, the endangerment of common bermudagrass gains an attention on the protection and ecological utilization of its resources. Bermudagrass grows as lawn and wild grass normally faces limited light and water deficit conditions. Thus, the main goal of the current study was determination of combined effects of drought and shade on Cynodon dactylon growth, meanwhile providing a theoretical framework for the management and development of tolerant accessions. In current study, stolons of 13 Cynodon dactylon genotypes were established under two treatments (control and combined drought + shade) and three replicates of each treatment on 9th of May 2024, for 30 days in the greenhouse of Yangzhou University Jiangsu China. After 30 days, plants were exposed to combined stressor as 50% shade created with a black net and 50% drought stress. After one month of treatment, the morphological, physiological and biochemical indices were measured under combined stress. The combined drought + shade interaction revealed the most-tolerant genotypes “G5” along longitude and “G10” along latitude gradients, while most-susceptible as “G2” and “G11” along longitude and latitudinal gradients, respectively. It was noticed that the genotypes of high latitudes showed strong stress tolerance due to the unfavorable environmental conditions. Such as low precipitation, insufficient water, sunlight and low temperature, while the longitude gradients with suitable annual rainfall, precipitation and temperature does not affect plant growth more significantly under combined stress conditions. The higher the latitude, the smaller the effect of stress will be. The regional difference of longitude gradient is not clear because several indicators showed null or less response against stress. Overall, the result suggests that under 50% shading and 50% water deficit treatment most-tolerant Cynodon dactylon genotypes showed better growth.