Grafting Compatibility of Solanum pennellii–derived Introgression Lines with a Commercial Tomato Scion

Tomato production is highly to water limitation, and grafting onto suitable is a practical method for improving crop resilience. However, the use of rootstocks depends on successful and compatibility with commercial scions. Solanum pennellii is a wild tomato relative with documented drought tolerance, and introgression lines derived from this species previously as drought tolerant may provide useful rootstock candidates while retaining a cultivated tomato genetic background. We evaluated grafting success and scion–rootstock compatibility of three drought-tolerant S. pennellii –derived introgression lines used as rootstocks for the commercial tomato hybrid COLT ® , with self-grafted COLT ® as the control. Seedlings were grafted 24 days after emergence using the cleft grafting method, healed for 5 days under high humidity, and evaluated in two greenhouse experiments in a randomized complete block design with three replications. Grafting success was assessed 7 days after grafting, and compatibility was determined 45 days after grafting using the scion-to-rootstock stem diameter ratio. Data were analyzed by analysis of variance and means were separated using Tukey’s honestly significant difference test at α = 0.05. Grafting success ranged from 88.3% to 100.0% in Experiment 1 and from 80.5% to 95.5% in Experiment 2, and the compatibility index ranged from 0.8985 to 0.9800 and from 0.8019 to 1.1144, respectively. These results indicate that the S. pennellii –derived introgression lines are compatible with a commercial tomato scion and may serve as candidate rootstocks for subsequent evaluation under water-limited conditions.