SHARMA, YASH PALTHAKUR, PANCY2016-11-152016-11-152013http://krishikosh.egranth.ac.in/handle/1/85668ABSTRACT Present investigation was conducted under two sub experiments viz. i) to study the effect of γ irradiation on secoiridoid content in M1 generation and ii) to study the effect of spacing and pinching on growth and yield parameters. Seeds of S. chirayita were subjected to different doses of physical mutagens (2 to 30 kR gamma rays) to study their impact on growth, yield and major bitter compounds at flowering stage. Maximum plant height (151.00cm), fresh aerial biomass (62.22g/plant), dry aerial biomass(20.72g/plant), fresh root biomass (5.05g/plant), whole plant fresh biomass (67.27g/plant) whole plant dry biomass (22.39 g/plant) was observed in 26kR γ rays doses. The impact of γ rays on two secoiridoid compounds namely amarogentin and amaroswerin showed an erratic and irregular trend, with maximum amarogentin in (i) leaves at 20kR and 22 kR γ rays dose, (ii) roots at 30kR and (iii) stems at 4kR and 8kR dose of γ rays. Amaroswerin content was recorded maximum in (i) leaves at 12kR γ rays dose and (ii) roots at 20kR and 30kR dose of γ rays. In stems, amaroswerin content decreased in comparison to control in all the treatments. Apart from changes in concentration of amarogentin and amaroswerin, some additional peaks in HPLC chromatograms were observed in roots of plants treated with 20kR to 30kR dose of γ rays. In spacing and pinching experiment, it was observed that with the increase in pinching height there is increase in all the growth & yield parameters. Among different pinching heights, maximum fresh aerial biomass/plant (65.34 g), dry aerial biomass/plant (23.16 g), fresh root biomass/plant (5.53 g), dry root biomass/plant (1.76 g), whole plant fresh biomass/plant (70.87 g), whole plant dry biomass/plant (24.92 g), expected fresh biomass yield (49.80 q/ha) and expected dry biomass yield (17.49 q/ha) were recorded under 60 cm pinching height. Among all the spacings, mean plant height (107.30 cm), number of branches (12.20), fresh root biomass (5.03g), dry root biomass (1.63g), expected fresh biomass yield (54.38 q/ha), expected dry biomass yield (19.12 q/ha) were maximum under 30x30 cm spacing.enplanting, biomass, spacing, pruning, yields, vegetative propagation, drying, developmental stages, sowing, biological developmentS. chirayita,SeedsThesis