A novel graft between pac choi (brassica rapa var. Chinensis) and daikon radish (Raphanus sativus var. Longipinnatus)

Abstract

Vegetable grafting has primarily been used in the commercial production of high-value crops in the Solanaceae and Cucurbitaceae families. In this study, we explored the feasibility of making a novel graft between pac choi (Brassica rapa L. var. chinensis) and daikon radish (Raphanus sativus L. var. longipinnatus) to create a plant with harvestable pac choi leafy vegetable above-ground, and a daikon radish taproot below-ground. 'Mei Qing Choi' pac choi (scion) was grafted onto 'Bora King' daikon radish (rootstock). Grafted pac choi-daikon radish plants did not show a decrease in SPAD value, canopy size, leaf number, leaf area, or above-ground weight compared with self-grafted pac choi plants. However, taproot formation was reduced in grafted pac choi-daikon radish plants, as shown by decreased taproot length, diameter, fresh weight, and dry weight compared with non- and self-grafted daikon radish plants. Surprisingly, grafting with radish increased the photosynthetic rate of the pac choi. This pilot study demonstrated the potential of creating a new pac choi-daikon radish vegetable product to help save growing space and minimize waste at consumption, as pac choi roots are not eaten and radish leaves are usually discarded. The inter-generic grafting between B. rapa var. chinensis and R. sativus var. longipinnatus could also provide a unique model system to help elucidate scion-rootstock synergy and above- and below-ground sink competition in horticultural crops.