Verma, R.K.Kanwar, Mithlesh Kumar2016-08-082016-08-082016120p.http://krishikosh.egranth.ac.in/handle/1/71614Observation recorded 42 characters early plant vigour bassal leaf sheath colour, ligules color, ligules shape, collar color, auricle color, internode color, flag leaf angle, panicle excertion, panicle type, stigma color, awning, sterile lemma color, hull color, seed coat color, threshability, aroma, days to 50% flowering, plant height, effective tiller per plant, panicle length, leaf length, leaf width, filled grains per panicle, unfilled grains per panicle, spikelet fertility percentage, spikelet sterility percentage, 100 grains weight, yield per plant, hulling percentage, milling percentage, kernel length, kernel breadth, kernel length breadth ratio, cooked kernel length, cooked kernel breadth, cooked kernel length breadth ratio, elongation ratio, elongation index and head rice recovery percentage. For screening of rice genotypes against cold temperature stress the genotypes which showed good performance are IR 11C115 followed by IR 11C134, IR 65199-4B-19-1-1, IR 72046-B-R-3-2-1, IR 74099-3R-5-1 and for high temperature stress, spikelet fertility is a more powerful indicator for screening at the reproductive stage than other stages. Based on spikelet fertility percentage genotypes viz. IR 10C112, IR 11C114, IR 11C115, IR 11C120, IR 11C128, IR 11C170, IR 65199-4B-19-1-1, IR 70868-B-P-11-3, IR 70865-B-P-6-2, IR 71895- 3R-26-2-1-2B-2, IR 74099-3R-5-1, IR 11C173, Poornima (LC), N-22 and IR 10C146 performed better under high temperature. The performance of rice genotype were evaluated through spikelet fertility percentage which ranged from 80.45% (IR 65199-4B-19-1-1) to 95.04% (IR 74099-3R-5-1) by comparing the date of flowering 21th April with maximum temperature 42℃. The analysis of variance indicated that the mean sum of squares due to replication were significant for days to 50% flowering, plant height, effective tiller per plant, panicle length, leaf length, leaf width and kernel breadth. The mean sum of squares due to genotypes were highly significant for most of the characters studied. The high genotypic and phenotypic coefficient of variation were recorded for filled grains per panicle followed by spikelet fertility percentage. Highest heritability was recorded for panicle length followed by days to 50 % flowering, head rice recovery, leaf length and effective tillers per plant. The highest geneticenPlant Breeding and Genetics, Heat and Cold tolerance, Correlation PathThesis