An efficient method for acclimatization: in vitro hardening of tissue culture-raised tea plants (Camellia sinensis (L.) O. Kuntze)

In the 21st century while there is all-round development in every sphere of science and technology, a major limitation in micropropagation technology still remains; a large number of plantlets of several species die during hardening and ex vitro transfer. In the present study, introducing an in vitro incubation period in plant growth regulator (PGR)-free medium followed by root induction of micropropagated tea shoots (Camellia sinensis (L.) O. Kuntze) and increasing it to 12 weeks instead of the usual 4 weeks gave excellent results. Secondly, cultures were grown in larger vessels, i.e. in 500 ml conical flasks in place of normal 250 ml conical flasks. Interestingly, prolonged incubation (12 weeks) significantly enhanced overall growth, i.e. length, stem girth, leaf number and leaf area of plantlets. The use of larger-sized culture flask also positively influenced growth. The above-mentioned two simple modifications in culture conditions improved overall growth of plantlets. Also, plantlets raised through prolonged culture were acclimatized with 94% survival efficiency in comparison to 46% with normal culture period, and showed improved growth performance on transfer to soil in the nursery, irrespective of the culture vessel size.