Optimization of low-cost potting mixture for hardening of in vitro raised plants of dragon fruit

Abstract: Dragon fruit cultivation is surging massively because of its high nutritional and medicinal value and profit to the farmers. Micropropagation offers healthy, vigorous and uniform planting material to meet the soaring demand. However, the high cost of tissue-cultured planting material prevents farmers from buying it. Commonly used potting media, peat, perlite, and vermiculite, contribute significantly to the higher cost of micropropagules. In this study, low-cost potting media such as soil, sand and vermicompost were evaluated as alternative potting media for hardening tissue-cultured plants of dragon fruit. Well-rooted micro shoots were transplanted into Protrays containing different proportions of soil, sand and vermicompost and the plant survivability, the number of shoots and roots and their respective length and chlorophyll content were recorded. Sand and vermicompost (1:1 v/v) were found to be the best potting media exhibiting 100% survivability (15 days of hardening of the plants), producing the highest number of shoots (7.66 shoots/plant) with a mean length of shoots (10.61 cm) and 11.27 roots per plant with a mean length of 10.38 cm root length (at 120 days of hardening). Cent per cent survivability was noticed even at 120 days after hardening. Sand and vermicompost, with less than 10% of the cost of peat, perlite and vermiculite may be used as low-cost potting media for the hardening of tissue-cultured plants.