Pheno-thermal response of Chrysanthemum under different environments in mid hills of Himachal Himalayas

Abstract

This paper briefly reports some effects of date of transplanting, row spacing and their orientation on the pheno-thermal response of Chrysanthemum. In order to study the effect of heat, photothermal and heliothermal units on the phenology of Chrysanthemum, an experiment was conducted during 2019-2020 on Solan Shringar cultivar of Chrysanthemum at experimental farm of Department of Environmental Science, Dr. Y S Parmar University of Horticulture & Forestry Nauni (30^o86'N, 77^o16'E and 1275 m amsl). The weather based indices were used for characterizing the thermal response to various phenophases of Chrysanthemum under different environmental conditions. The maturity was differed by 13 days for early, mid and late transplanting dates for which the accumulated range of growing degree days was 2278-2291, 2062-2067 and 1826-1827^o C days; photothermal unit was 11240-11366, 9266-9336^o C days under different treatments. Likewise, minimum heliothermal unit was required by the treatment D₃S₁O₂ (23602^o C days) and maximum under the treatment D₁S₁O₂ (29958^o C days). Highest and lowest heat use efficiency was recorded under D₁S₁O₁ (5.4) and D₃S₂O₂ (2.8) treatment, respectively. The weather indices explained 73-98% variation in vegetative and 88-92 % reproductive phenophase of Chrysanthemum under different treatments.