Foliar application of plant growth regulators modulates the productivity and chemical profile of damask rose (Rosa damascena Mill.) under mid hill conditions of the western Himalaya

Abstract

Damask rose (Rosa damascena Mill.) is one of the most valuable aromatic crops used in the flavors, perfumery, cosmetics, and pharmacological industries. However, environmental conditions and plant nutrition plays a key role in the productivity of the crop. The study aimed to understand the effect of plant growth regulators on growth, yield, and quality profile of damask rose. Thus a field experiment was conducted at CSIR-Institute of Himalayan Bioresource Technology experimental farm, Palampur, India during 2018-19. The experiment consists of three growth regulators viz., methyl jasmonate (at 25, 50 and 75 μL L-1), diphenyl urea (at 10, 15 and 20 mg L-1), kinetin (at 25, 30 and 35 mg L-1), and control (deionized water) in randomized block design with three replications. Growth regulators significantly affected yield attributes, yield, and composition of essential oil. Number of flowers plant-1 (73.3) and fresh flower weight plant-1 (203.5 g) were significantly higher in diphenyl urea at 15 mg L-1 as compared with other treatments. Applications of diphenyl urea at 15 mg L-1, kinetin at 30 and 35 mg L-1 increased the fresh flower yield by 56.0, 41.6, and 35.8%, respectively, as compared with control. Essential oil content was significantly higher with methyl jasmonate at 50 μL L-1 and diphenyl urea at 15 mg L-1. Application of diphenyl urea at 15 mg L-1 and kinetin at 30 mg L-1 increased essential oil yield by 72.8 and 52.8%, respectively, as compared with control. A total of 26 essential oil compounds contributed to 79.6-83.8%. The biplots of principal component analysis also indicated the higher positive correlations among the major hydrocarbons and revealed that there is an inverse relationship between monoterpenes and hydrocarbon compounds. So, from the current study, we have concluded that as per the need for the aroma and perfumery industry, different plant growth regulators can be used to enhance fresh flower yield and quality of damask rose under the mid hill conditions of the western Himalaya.