Vol. 11, Issue 7 (2022)

Author(s):
A Sheeba

Abstract:
Drought stress caused by water deficit is the most impacting adverse condition for rice production. Selection under field condition for drought tolerance is slow in attaining progress due to the inherent variation in the field. In vitro selection of tolerant cell lines is one of the promising areas of plant tissue culture which eliminates the environmental discrepancies by maintaining controlled condition. The present investigation was framed to select superior genotypes for drought tolerance by screening forty rice hybrids along with their parental lines under in vitro and in vivo conditions. Matured seeds of above genotypes were inoculated in the callus induction media MS + 2mg / lit 2,4 - D + 0.5mg / lit kinetin + 1g / lit CH and the developed callus were screened in the media containing PEG in varied concentration viz., 0.0%, 0.5%, 1.0%, 1.5% and 2.0%. Callus morphology, callus fresh weight and proline content of callus were studied. Callus morphology scores and fresh weight of callus tend to reduce with increasing concentrations of PEG in both parents and hybrids thus indicating the adverse effect of PEG on the growth of tissues. Proline content increased with the increasing level of PEG concentration in the tolerant genotypes. Based on callus morphology, callus weight and proline content, the genotypes Norungan and Varappukudanchan in parents and GD 99033/PMK 2, GD 98049/Norungan and GD 99017/PMK 2 in hybrids could be adjudged as most tolerant genotypes. Among the above three hybrids, GD 99033 / PMK 2 and GD 98049 / Norungan showed better drought tolerance coupled with yield when evaluated under rainfed environment demonstrating that the cell lines surviving under in vitro drought stress also have adjustments in their hostile environment.