PHYSIOLOGICAL CHARACTERIZATION OF TRADITIONAL RICE LANDRACES UNDER DROUGHT STRESS INDUCED BY POLYETHYLENE GLYCOL

An investigation was carried out to study the drought tolerance potential of fifteen traditional rice landraces using PEG 6000.Fifteen traditional landraces were subjected to drought stress at five concentrations such as -2, -4, -6, -8 and -10 bars of water potential.Under this study, growth parameters including germination per cent, shoot length, root length, seedling vigor index, root fresh weight, shoot fresh weight, root dry weight, and shoot dry weight were recorded.Further, physiological parameters including soluble protein, nitrate reductase, and proline content were also recorded.Out of 15 genotypes studied, two genotypes viz., Mettumaranellu and Chengalpattu sirumani recorded significant germination per cent (above 40%) over the mean.The maximal root length observed at these bars, was only 3.5 cm in -8 bar and 2.3 cm in -10 bar (Chengalpattu sirugamani).Chengalpattu sirumani maintained significant vigor index even at -6 bars making it the best candidate for drought tolerance.Based on the data, it was found that the variety Chengalpattu sirumani had the maximum root fresh weight (145.55 mg) under -8.0 bar drought circumstances.Chengalpattu sirumani showed higher accumulation of soluble protein (12.15 mg g -1 ), nitrate reductase activity (21.25 g NO2 g -1 h -1 ) and proline content (11.26 mg g -1 ) than other traditional landraces.According to the findings, Chengalpattu sirumani, Pisini, Mapillai samba, and Karungkuruvai exhibited a high degree of drought tolerance, as evidenced by their notable germination rate, high seedling vigour index and root length compared to the general mean.The traditional landrace Mettumaranellu exhibited a higher germination per cent across all levels of water potential but failed to show a significant vigor index.