000			05232nam a22001817a 4500
999			_c289770 _d289770
082			_a630.28 _bARA/ID PG
100			_aAravind Krishnan R
245			_aIdentification of superior genotypes for water stress tolerance in rice (Oryza sativa L.) for south central laterites of Kerala
260			_aVellayani _bDepartment of Plant Breeding and Genetics, College of Agriculture _c2022
300			_a146p.
502			_aM Sc
520			_ahe present investigation entitled “Identification of superior genotypes for water stress tolerance in rice (Oryza sativa L.) for south central laterites of Kerala” was conducted at Farming Systems Research Station, Sadanandapuram, Kottarakkara during 2019-21 with an objective to identify and characterize the traditional as well as released rice genotypes of Kerala for water stress tolerance using phenotypic and biochemical markers, suitable for south central laterites of Kerala. The study comprised of thirty genotypes collected from RARS, Pattambi, Department of Seed Science and Technology, College of Agriculture, Vellanikkara, KAU, Thrissur and ICAR- NBPGR, New Delhi. Study was conducted in two experiments viz. laboratory and field study. In the first experiment (Experiment-I), thirty genotypes were evaluated for moisture stress tolerance at seedling stage for seven different morpho-physiological characters viz. Germination percentage, speed of germination, root length, shoot length, seedling dry weight, seedling vigor index 1 and seedling vigor index 2 in laboratory using PEG 6000 (Polyethylene Glycol- 6000) at five different concentrations of 0, 5, 10, 15, 20 percentage (%). The study was conducted in factorial completely randomized design, replicated thrice and the twenty-one tolerant genotypes were selected for field study. In the second experiment (Experiment-II), twenty-one best performing genotypes including the high performing standard check variety Apo in randomized block design were selected and evaluated in the field where irrigation was withheld for 10 days at critical growth stages. The seeds were sown on raised beds of 4 m2 size at a spacing of 20 cm х 20 cm and cultural operations were adopted as per the “Package of Practices (2016)” of Kerala Agricultural University. Genotypes were evaluated for twenty-four characters which included different biometric, physiological and biochemical observations. Significant difference was observed among genotypes for all the characters studied in both field and laboratory experiments. Genetic parameter analysis was performed for 21 characters and for all the characters PCV values were higher than GCV values indicating the influence of environment. The phenotypic and genotypic coefficient of variation were maximum for recovery after stress release and minimum for days to 50 % flowering. Heritability was high for all the characters except leaf rolling score and genetic gain was high for all the selected characters. Correlation studies revealed significant positive correlation for all the selected characters except spikelet sterility, which exhibited significant negative correlation with grain yield. Path analysis conducted for eleven characters showed significant correlation with grain yield and also revealed that relative water content recorded high positive direct effect on grain yield. High positive indirect effect on grain yield was recorded by grain weight per panicle via spikelet sterility. Genetic divergence analysis using Mahanalobis D2 statistic following Tocher’s method grouped the twenty-one genotypes into five clusters. Cluster II with 10 genotypes was the largest followed by cluster I (8 genotypes) and cluster III, IV, V were solitary. The highest intra cluster distance was recorded among the genotypes of cluster II. Whereas highest inter cluster distance was observed between the genotypes of the clusters I and V. Among the selected characters, the relative contribution towards the genetic divergence was much higher for root length. In the present investigation, genotypes Parambuvattan, Apo, Vaisakh and Chuvannavattan were identified as the best water stress tolerant ones under PEG induced stress conditions based on various seedling parameters during laboratory experiment. While, field evaluation of the genotypes Vaisakh, Karanavara, Karuthadukkan, Kattamodan, Parambuvattan and Onamottan exhibited good and comparable grain yields with the Universal drought tolerant check Apo under field level drought conditions. Thus, it can be concluded that Parambuvattan, Karanavara, Karuthadukkan, Kattamodan and Onamottan were recognised as best performing genotypes capable for moisture stress tolerance despite the performance of universal check, Apo and high yielding Vaisakh. The best performing genotypes identified in the study can be recommended for upland cultivation in south central laterites of Kerala and also for molecular analysis in future rice breeding programs by Kerala Agricultural University.
650			_aPlant Breeding and Genetics
650			_aRice
650			_aOryza sativa
700			_aBindu M R (Guide)
942			_2ddc _cTH