SANKHYAN, H PRAJENDER KUMAR2021-10-252021-10-252021-10https://krishikosh.egranth.ac.in/handle/1/5810177234ABSTRACT The present investigation entitled, "Evaluation of high resin yielding half sib families of Pinus roxburghii Sargent", was carried out at Shilli Conservation Reserve, Solan during the year 2020-2021 to evaluate different growth traits (height, diameter at breast height, bark thickness, crown height and crown length), needle characteristics (colour, length, thickness and number of stomata per mm of row), wood traits (moisture content, specific gravity and tracheid length) of different half sib Chir pine families as well as to evaluate the oleo-resin yield traits of different half sib Chir pine families. The study revealed that all the traits varied significantly, with mean values diameter at breast height (31.10 cm), height (17.79 m), bark thickness (2.81 cm), crown length (10.75 m), crown height (6.95 m), needle length (25.57 cm), needle thickness (0.70 mm), number of stomata per mm of a row (9.53), wood moisture content (80.95%), specific gravity (0.42) and tracheid length (1.66 mm).Variability estimates, genetic parameters, correlation studies, principal component analysis and divergence studies exhibited high variability among all the half sib families. Characters which exhibited high heritability like bark thickness (H2 = 0.80), tracheid length (H2 = 0.92), no. of stomata (H2 = 0.91), followed by higher genetic gain. Genetic divergence was studied through cluster analysis. The average oleoresin yield was found to be 430.97 g. The turpentine content of oleoresin ranged from 19.45 per cent to 25.4 per cent and highest rosin content 78.60 per cent while the lowest 72.68 per cent. Resin yield was significant with DBH (0.465) and needle length (0.315) and highly significant with bark thickness (0.721). Higher oleoresin yields have been recorded in family which have maximum diameter. It may be concluded that evaluation of the Chir pine diversity can be very useful in qualitative and quantitative improvement of different traits studied. The seed of these high resin yielding families can be used in establishment of seed orchard to increase its number of populations so as to increase the overall resin production.EnglishThesis