Enhanced micropropagation protocol of ex vitro rooting of a commercially important crop plant Simmondsia chinensis (Link) Schneider

Abstract

A micropropagation protocol was developed by further improvement of prevailing methods using proven germplasm for ex vitro rooting and addressed the effect of the number of subcultures on the rooting ability of shoots. A comparative study was done between in vitro rooting method and ex vitro rooting method. Using the ex vitro rooting method a plantlet could be produced in 135 days, which was in a shorter time compared to the in vitro rooting method - 180 days. The best axillary shoot bud induction was observed on Murashige and Skoog (MS) medium supplemented with 4.6 μM thidiazuron (TDZ) with 5 shoot buds per explant. In the shoot cluster, which was subcultured on MS medium supplemented with 2.3 μM TDZ, the rate of shoot multiplication increased in the 3rd subculture. The maximum mean number of shoots per explant (20) was obtained at the 3rd subculture on the same medium. Shoots were harvested at the 1st, 3rd and 5th subculture and pulse treated for root induction. The highest rooting (95%) was achieved from the 3rd subculture onwards with pulse treated shoots for fifteen days. The rooted plants could be established in a greenhouse with 99% survival. Ex vitro rooting is a promising method to reduce the time for plant generation. The resultant plantlets well established in pots and fruiting was observed within a year.

Keywords

• fruiting
• genotype
• jojoba