Coconut Fiber Improved the Quality and Abnormalities of Passiflora edulis Sims Plantlet in Microponic System

Hoang Tung, Tran Hieu, Ha Ngan, Bui Vinh and Duong Nhut

Background and Objective: A microponic (MP) system which combinates between hydroponic and micropropagation, has been successful on some plants and there is no research in Passiflora. Hence, in this study MP system with coconut fiber as a substrate was used to evaluate the growth, physiology and chemistry of plantlets as compared to those in a micropropagation (MO) system with agar as gelling agent. Materials and Methods: The coconut fiber (20 g) was autoclaved and placed in 500 mL round plastic boxes as an MP system with Millipore membrane (2 cm in diameter) used for in vitro rooting experiments. The percentage of in vitro rooting, plantlet growth, change of humidity in round plastic boxes (MO and MP systems) were obtained after 8 weeks of culture. The antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), phenolic was investigated. Results: The 2-cm shoots pre-treated with 2.5 mg/L indole-3-butyric acid (IBA) and culture in the MP system exhibited higher in vitro rooting and plantlet growth after 8 weeks of culture. Moreover, MP produced plantlets displaced less abnormal phenomena compared to MO-plantlets. In this treatment, SOD, CAT and APX contents were higher; and ethylene and phenolic contents were lower than those in the MO treatment. The changes in relative humidity (55 to 63%) in MP treatment were lower than those in the MO treatment (55 to 92.33%) after 8 weeks culture. Conclusion: The MP system with coconut fiber as a substrate has proven effective in improving the in vitro rooting quality of plantlets by reducing a hyperhydricity, leaf yellowing, leaf abscission and callus at the root. Besides, MP plantlets acclimatized and grew higher than MO plantlets after 8 weeks in the greenhouse.

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