In vitro selection for drought tolerance in rice (Oryza sativa L.)

Polyethylene glycol (PEG 6000) in different concentrations is commonly used as osmoticum to reduce the water potential and create osmotic stress in the culture medium. Hence the present investigation was framed to select superior variants from eight parents (NPT 107, PMK 3, MDU 5, ASD 16, Vellaichithiraikar, Mattaikar, Nootripathu. and Norungan) and their 28 hybrids by studying the fresh weight of callus, callus morphology and proline accumulation in the presence of osmoticum. The genotypes ASD 16, Mattaikar, Norungan, NPT 107/MDU 5, NPT 107/ASD 16, NPT 107/Nootripathu, PMK 3/ASD 16, PMK 3/Vellaichithiraikar, PMK 3/Mattaikar, PMK 3/Nootripathu and MDU 5/Norungan exhibited earlier callus induction and higher callusing frequency irrespective of the media concentrations used. Combining callus morphology, callus weight and proline accumulation under media containing PEG for selecting tolerance genotypes, Mattaikar and Norungan in parents and NPT 107/MDU 5, NPT 107/ASD 16, NPT 107/Nootipathu and PMK 3/Norungan in hybrids could be adjudged as the most tolerant among the genotypes studied.