2017 ASHS Annual Conference

Although some research has been conducted with grafted peppers using specialized pepper rootstocks worldwide, the use of rootstocks from other solanaceous species outside the pepper (Capsicum) genus for pepper grafting has not been well explored in the United States. Our project goals were to determine the feasibility of intergeneric grafting between the Capsicum and Solanum genera and to identify the utility of grafted pepper (C. annum) plants for commercial high tunnel production in the Central United States. We grafted ‘Karisma’ bell peppers onto both ‘Maxifort’, a popular tomato rootstock, and ‘Scarface’, a pepper rootstock. Our grafting success rate was approximately 93%, though the grafted peppers spent two to five days longer in the healing chamber than is typical for tomatoes. We set up two trials, using a randomized complete-block design (n=4). The treatments included nongrafted ‘Karisma’ as well as ‘Karisma’ grafted onto both ‘Maxifort’ and ‘Scarface’ rootstocks. One trial was located in a high tunnel at the Olathe Horticulture Research and Extension Center in Olathe, Kansas and a second was performed in the open field at the John C. Pair Horticulture Center in Haysville, Kansas. We recorded harvest data and plant height, and plants were destructively sampled at the end of the season to measure both above and below-ground biomass. While location had a strong effect on multiple characteristics of both grafted and nongrafted plants, rootstock also had a significant effect on numerous parameters. In the high tunnel trial, plants with ‘Maxifort’ rootstock had 50% less above ground biomass, 27% lower compactness, 0.085 lbs (29%) smaller fruit, and 6.12 lbs (48%) less total yield on average than the nongrafted plants. We observed similar but more pronounced relationships in the open field trial. Plants grafted to ‘Scarface’ showed no significant difference in total yield, fruit size, or biomass as compared to nongrafted plants. However, plants grafted to ‘Scarface’ had 0.84 g/cm (22%) greater compactness than nongrafted plants in the high tunnel trial (P = 0.063). We intend to do further work to determine the reason(s) for the poor growth of pepper plants grafted to tomato rootstocks. Peppers grafted onto ‘Karisma’ rootstock may exhibit increased plant compactness with no loss of yield as compared to nongrafted plants, which could be valuable for increasing yield on a per square foot basis. More research is needed to confirm the data presented here and explore other potential pepper rootstocks for growers in the United States.