Gurumurthy, R.Karthik, M.S.2021-11-062021-11-062016-06https://krishikosh.egranth.ac.in/handle/1/5810177776A field experiment was carried out at Hi-Tech Horticulture unit, Saidapur farm and the laboratory experiment was carried at seed quality testing and research laboratory National Seed Project, UAS Dharwad during 2015-16 to study the effect of growth regulators, stages of harvest under different growing conditions on seed yield and quality and manipulation of dormancy in lettuce. The growing condition shade house registered significantly higher number of leaves per plant (39.27), leaf area index (7.55), number of capsules per plant (507), seed yield per hectare (423.23 kg), seed germination (90.78 %), seedling vigour index (743.25) and lower electrical conductivity of seed leachate (0.93 dS/m). The growth regulator spray of GA3 (20 ppm) + BAP (30 ppm) registered significantly higher number of leaves per plant (41.92), leaf area index (7.96), number of capsules per plant (560.83), seed yield per hectare (442.39 kg), seed germination (93.06 %), seedling vigour index (785.41) and lower electrical conductivity of seed leachate (0.87 dS/m). Among the different stages of harvest, harvesting at 50 % feathering recorded significantly higher seed yield per hectare (435.09 kg), seed germination (91.54 %) and 1000 seed weight (0.93 g). The second experiment was carried out to study the effect of different chemicals, growth regulator and light treatment on germination and seedling quality in lettuce. Significantly higher germination percentage (95 %) was recorded with the red light treatment of 660 nm for 15 min but the seedling vigour index (629) was recorded significantly higher in case of treatment with GA3 at 100 ppm for 60 min.EnglishThesis