Ex vitro rooting of micro-propagated intergeneric papaya through phloroglucinol

Abstract

Micropropagation techniques of papaya have been optimized Worldwide. However, standard rapid multiplication technique of papaya at commercial level with economically viable is still lacking. Since establishment of in vitro culture pretty easy at the same time in vitro rooting of papaya is still difficult. However, in vitro rooting is costly and the roots initiated in vitro do not have lateral branches and root hairs, making them difficult to acclimatize. Hence ex vitro rooting induction of micro-propagated plantlets and acclimatization were conducted. In vitro cultures were established using shoot tips from seedlings of selected advanced intergeneric hybrid. They were inoculated onto Murashige and Skoog (MS) medium + 3% sucrose + 1 µM BAP + 1 µM GA3 + 0.1 µM IAA + 0.25% phytagel until plantlets were obtained. For ex vitro rooting, plantlets were cultured with various concentrations of phloroglucinol (PG) to investigate the appropriate condition of rooting. Direct rooting (82%) of papaya micro-cutting into potting medium (perlite + vermiculite + coco peat; in the ratio of 1:1:2) subsequent dipping into phloroglucinol was more effective than in vitro rooting and led to amended survival percentage (82%) of micro-cutting during acclimatization. PG at 1000 µM was extra effectual than IBA in encouraging root development. Sachet method was found to be the best appropriate for ex vitro rooting and hardening of papaya with single-step acclimatization.