Optimal nutrient management is critical for optimizing flowering, yield, quality and improving soil health. A key approach for making chrysanthemum crop cultivation profitable is balanced fertigation at the right time. This is possible by fertigation through drip. The present study was designed in 2019–2021 at a model floriculture center, Pantnagar, to investigate the response of split application of NPK through drip fertigation on flowering attributes, yield, biochemical activity and soil nutrient status of chrysanthemum. Plants received application of NPK with five treatment combinations: T1-NPK @ 100:150:100 kg/ha/year, T2-NPK @ 100:150:100 kg/ha/year, T3-NPK @ 100:150:100 kg/ha/year, T4-NPK @ 75:112.5:75 kg/ha/year and T5-NPK @ 75:112.5:75 kg/ha/year at vegetative, bud and flowering stages. The results reveal that the plants treated with treatment T3 (NPK @ 100:150:100 kg/ha/year) exhibited maximum increases in floral bud diameter (31.45%), number of inflorescences per branch (24.44%), diameter of inflorescence (15.32–28.44%), weight of inflorescence (24.30%), stem diameter, inflorescence stem length, number of inflorescences per plant (6.16%), number of inflorescences per hectare (53.46%), chlorophyll a content, chlorophyll b content, total chlorophyll content (40.20%), carotene content of inflorescence (69.56%), organic carbon (1.22-fold), available nitrogen content (7.46%), available phosphorus and available potassium (1.14-fold) compared to the control. Conclusively, the results suggest that split application of NPK through drip fertigation may improve the inflorescence attributes, yield, biochemical activity and soil nutrient status of chrysanthemum.

High aesthetic and economic importance of dahlia stimulates breeders for the development of new cultivars. To determine the lethal dose (LD50) of gamma rays in different cultivars of dahlia, an experiment was conducted at MFC, GB Pant University of Agriculture and Technology, Pantnagar. Rooted cuttings of three dahlia cultivars viz., Jyotsana, Agni and Glory of India were exposed to acute (⁶⁰Co) gamma ray irradiation at 0.0 (Control), 1.0, 1.5, 2.0, 2.5 and 3.0kR to determine the lethal doselevel. Probit analysis for extrapolated LD50 in different cultivars of dahlia for mortality was 2.07, 1.91, and 1.87 kR for Jyotsana, Agni and Glory of India, respectively indicating the higher sensitivity for cultivar Glory of India. There was direct correlation between dose of gamma irradiation and mortality of cuttings. Maximum mortality (47.00%) was observed at 3.0 kR while, minimum (10.00%) was observed at 1.0 kR dose of gamma rays treatment. Different cultivars also exhibited significant differences for mortality percentage by gamma rays irradiation. The LD50 values for maximum survival percentage of cuttings can be fixed at 2.07, 1.91 and 1.87 kR of gamma rays irradiation for cvs. Jyotsana, Agni and Glory of India, respectively.