Enhanced rooting and shoot proliferation in micropropagation of ‘MKR1’ dwarfing persimmon rootstock

Abstract

Persimmon rootstocks (Diospyros kaki Thunb.) are typically propagated from seedling rootstocks, but this often results in excessive vigor and inconsistent growth, complicating orchard management. This study aimed to improve a micropropagation protocol for ‘MKR1,’ a dwarfing persimmon rootstock, based on the method of Tao and Sugiura (1992). Both zeatin, an expensive cytokinin, and BA, a more affordable option, were evaluated for in vitro shoot tip establishment and proliferation. Microcuttings grown on full-strength MS medium showed higher rooting and survival rates than those on MS (1/2 N), commonly used for persimmons. After 60 subcultures, BA-treated shoots experienced reduced proliferation rates, which were restored with a low concentration of zeatin without affecting rooting. The original protocol, which required 40 days of culturing in agar-solidified medium followed by transplanting to vermiculite-filled pots, proved cumbersome. A direct rooting method, involving immediate potting after quick-dip IBA treatment, was unsuccessful. However, a semi-direct method with a 10-day dark incubation prior to transplanting produced comparable rooting rates to the original method. Further, adding IBA directly to the medium eliminated the need for quick-dip treatments, allowing successful transplanting into peat pellets after 10 days, achieving high rooting success and robust plantlet growth. This streamlined protocol reduces production time and costs, offering an efficient approach for large-scale propagation of ‘MKR1’ plantlets.