Dr. Parminder Kaur BawejaSRISHTI SHARMA2024-03-012024-03-012023-11-24https://krishikosh.egranth.ac.in/handle/1/5810207246The present investigation entitled “Phenological studies on Silybum marianum under different Environments in mid hills of Himachal Pradesh)” was conducted at the Experimental Farm of Department of Environmental Science, Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.) with effect from October, 2022- June, 2023.The study aimed to assess the phenology and quality of Silybum marianum L. in subtropical region of western Himalayas, planned with five sowing dates (October 20, October 30, November 10, November 20 and November 30) and two spacing i.e., 40 cm x 60 cm and 60 cm x 60 cm replicated thrice in a randomized block design (RBD). The agro-morphological characteristics were assessed. Thermal indices viz., AGDD, AHTU and APTU based on maximum/minimum temperature, sunshine hrs. and day length with base temperature of 5oC were simulated for ten phenological stages viz., germination, leaf development, formation of side shoots, rosette growth, development of harvestable plant biomass, inflorescence emergence, flowering, development of fruit, ripening and senescence. The results revealed that planting dates and spacing had a significant impact on all agro morphological characteristics attained the tallest plants (158.35), greater plant spread (78.52 cm), leaf area (303.09 cm2), number of flower head per plant (23.28) and maximum biomass yield (11.19 q ha-1) for early sown crop i.e., 20th October 2022 and 30th October 2022 under wider spaced (60 cm x 60 cm) sown crop. Late sowing (D4) with wider spacing (60 cm x 60 cm) resulted in highest number of branches (side shoots) per plant (16.50) , capitulum diameter (5.58 cm), fresh weight of flower head per plant (11.57g), dry weight of flower head per plant (11.03), flower heads per plant (22.20), number of seeds per flower head (116.50) and seed yield (48.08 g). The simulated AGDD (1622.12 oC day), AHTU (11868.70oC day hr ), APTU (18582.40oC day hr) for fruit development was revealed in 20 November 2022 sown at 60 cm x 60 cm (D4S2 ) spaced crop combination which attained best results in terms of quality parameters. Finally, the developed predictive model based on AGDD was assessed as best for seed yield prediction with 62% predictability. The study further opens the way for farmers and entrepreneurs to grow Silybum marianum L. successfully by cultivation of Milk Thistle as medicinal crop throughout Himachal Pradesh by adjusting the sowing windows as 20 November with addition of spacing (60 cm x 60 cm) for commercial cultivationEnglishThesis