Establishment of Integrated Propagation System on Grafting Plantlets of Passion Fruit (Passiflora edulis)

Abstract

As a result of virus disease, producers have to renew passion fruit plantlets every year to ensure yield and fruit quality in Taiwan. Currently, the entire procedure—from the preparation of rootstock seeds to having plantlets ready for planting—may take ∼3 months. The shortage of grafted plantlets in internal and foreign markets is a continuous challenge for the industry. The objective of this study is to improve the production mode to establish a rapid production system of grafted plantlets. The results show that the germination rate and time of rootstock seeds improved remarkably at 30 °C. The final germination rate was 100% within 10 days on average. Application of a complex chemical fertilizer Hyponex No. 4 solution, diluted 1000-fold, by soil drench weekly resulted in seedlings ready for grafting 28 days after treatment. Stem diameter reached 2.5 mm and plant height was ∼10 cm. After grafting, keeping the plantlets at 25 °C with a relative humidity of more than 85% ensured all incisions were healed within 7 days. After moving the plantlets to a semishaded greenhouse for hardening, and maintaining the same temperature and relative humidity for another 7 days, the propagation process was complete. Compared with double-node and shoot-tip scions, the growth and plantlet height of the single-node scion were not the best. However, considering the convenience of scion acquisition and the high rate of propagation, the use of a single-node scion is recommended. It takes only 56 days to propagate grafted plantlets, which is 1 month less using current processes.