Differential Rooting Pattern Observed in Tissue Culture Regenerated Plantlets from Different Explants of Jatropha curcas L.

Abstract

In an attempt to optimize an in vitro regeneration protocol, both direct and indirect, from different explants of Jatropha curcas L., different rooting patterns were observed from the regenerated plantlets in different concentrations of auxins. The rooting pattern was classified into four types based on their morphology as hairy fibrous roots, tap root-type, thin long roots, and thick short roots. Observations were recorded for length, number, thickness and strength of the roots. Better survivability and establishment was noted for the plantlets with hairy fibrous root followed by tap root-type system and thick short roots. Establishment was also dependent on the number of roots and root length. Plants with more than five roots and root length (2–4 cm) showed better survivability upon hardening compared to plants with lesser roots. The highest frequency of root induction from shoot tip-derived plantlet was observed on the full MS medium with 0.5 mg/L IBA and 30 mg/L ascorbic acid and for leaf, cotyledon and petiole explant on MS supplemented with 0.5 mg/L IBA. Hardening survival was more than 80% for well-rooted plantlets. The study shows the effect of different rooting patterns on survivability upon hardening which is very important from micropropagation point of view, where we want higher success rate for maximum economic gain