Impact of drought stress and rootstock on growth, compatible osmolytes, and flavonoids of Daphnis tomato

Greenhouse vegetable production faces challenges in regions prone to drought and water shortages. Grafting offers opportunities to enhance performance under stress conditions. This study evaluated the growth and biochemical responses of Daphnis tomato grafted onto different rootstocks under different irrigation levels. In a greenhouse experiment, seven Solanaceous rootstocks were used and the plants were subjected to three irrigation regimes (3-day interval as control, and 6-day and 9-day intervals as moderate and severe drought stresses) for four months. Results showed significant effects of irrigation intervals and rootstocks on growth and biochemical characteristics. Increasing irrigation interval led to the reduction in shoot fresh weight (SHFW), root length (RL), and yield. Certain rootstocks (Solanum cheesmaniae, S. lycopersicum var. cerasiforme) outperformed others in SHFW, RL, and yield. Also, rootstocks influenced the accumulation of total phenolic compounds (TPC), total soluble carbohydrates (TSC), and total flavonoid content (TFC). S. lycopersicum var. cerasiforme and S. cheesmaniae showed the lowest levels of these compounds. The interaction of irrigation intervals with rootstocks was significant for root fresh weight, shoot-to-root ratio, and leaf proline content. S. lycopersicum var. cerasiforme and S. cheesmaniae maintained root biomass under severe drought stress, while S. nigrum exhibited efficient resource allocation to the shoots under severe drought stress. Leaf proline content increased under severe drought stress in specific rootstocks. In conclusion, the type of rootstock influenced the growth and biochemical characteristics of the Daphnis tomato under water-deficit stress conditions. S. cheesmaniae, and S. lycopersicum var. cerasiforme demonstrated better growth, while certain rootstocks exhibited higher levels of biochemical compounds. These findings emphasize the importance of rootstock selection for enhancing drought tolerance in tomato cultivation and show the significance of some biochemical compounds in determining the water status of the greenhouse tomato.