Producing a Grafted and a Non-Grafted Tomato Plant from the Same Seedling

Abstract

Growing grafted hybrid tomato (Solanum lycopersicum) cultivars in greenhouse operations is gaining popularity worldwide. The costs of producing grafted plants remain a deterrent to the smaller producer. After removing plant tops to use as scions for grafting tomato plants, the stumps that have well-developed root systems and cotyledon leaves are usually discarded with the root media and containers. If productive plants can be produced from sprouts on the stumps, they can be used as non-grafted hybrids at the same farm or sold to other growers for income to defray part of the grafting costs. A 2-year greenhouse study examined the effects of three propagation methods and three tomato cultivars on plant yield and related traits. Seedling, grafted, and stump sprout plants of the hybrid cultivars Geronimo, Quest, and Starbuck were used in this study. Plants grafted on ‘Maxifort’ rootstock had greater stem diameter (P < 0.0001) below the first and third clusters than the seedling or stump sprout plants. The seedling plants had greater stem diameter than stump sprout plants below both clusters. During the first 3 weeks of harvest, seedling plants produced greater yields (P < 0.0001) than grafted or stump sprout plants and the differences were cultivar related. ‘Quest’ was the only cultivar that produced similar yields (2.8 vs. 2.3 lb) as a seedling or a grafted plant during the first 3 weeks of harvest. Tomato plants propagated by all three methods produced similar yields and fruit weight in the remaining 16 weeks of harvest. Cultivars had no significant effect on yield during the first 3 weeks of harvest (P > 0.05), but their yields were significantly different during the remaining 16 weeks of harvest (P < 0.0001). The apparent reason for yield advantages of the seedling plants during the first 3 weeks of harvest was the uninterrupted growth during the seedling stage. Propagation method had no specific influence on fruit quality attributes. On the bases of this study, producing productive tomato plants from stump sprouts is a feasible cultural technique that can reduce losses associated with plants used in grafting. It also allows the repeated use of the soilless media and the seedling containers. The produced plants can generate substantial income for businesses that graft a significant number of tomato seedlings. For this cultural method to work, grafting should be timed to allow the stump sprout plants to grow for at least 5 weeks before planting in the grow bags. This practice is normally followed in producing transplants from seeds.