Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas

RESEARCH ARTICLE Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas Meenakshi Thakur ID1,2, Vinod Bhatt3, Rakesh Kumar1,2* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Academy of Scientific and Innovative Research, New Delhi, India, 2 Agrotechnology of Medicinal, Aromatic and Commercially Important Plants Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur (HP), India, 3 Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology, (Council of Scientific and Industrial Research), Palampur (HP), India * Abstract OPEN ACCESS Citation: Thakur M, Bhatt V, Kumar R (2019) Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas. PLoS ONE 14(4): e0214672. https://doi.org/10.1371/journal.pone.0214672 Editor: Manuel Joaquı́n Reigosa, University of Vigo, SPAIN Received: November 28, 2018 Accepted: March 18, 2019 Published: April 4, 2019 Copyright: © 2019 Thakur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. A field experiment was conducted at the experimental farm of CSIR-Institute of Himalayan Bioresource Technology, Palampur, India for two consecutive years (2015–16 and 2016– 17). The aim of the study was to test the hypothesis whether different shade level and mulch type would influence the growth, flower yield and essential oil profile of R. damascena. Yield attributes viz., numbers of flowers plant-1, fresh flower weight plant-1, flower yield, and essential oil yield were significantly higher under open sunny conditions as compared to 25% and 50% shade levels. However, plants grown under 50% shade level recorded significantly higher plant height (cm), plant spread (cm) and the lowest numbers of branches as compared to control. Among mulches, black polyethylene mulch recorded significantly higher growth, and yield attributes of damask rose as compared to other mulches. Black polyethylene mulch recorded 74.5 and 39.2% higher fresh flower yield as compared to without mulch, during 2015–16 and 2016–17, respectively. Correlation studies showed a positively significant correlation between quality and quantity traits. A total of twenty-six essential oil compounds were identified which accounted for a total of 88.8 to 95.3%. Plants grown under open sunny conditions along with the applications of black polyethylene mulch produced a higher concentration of citronellol and trans-geraniol. Damask rose planted in open sunny conditions and mulched with black polyethylene sheet recorded significantly higher flower yield. Data Availability Statement: All relevant data are within the paper. Funding: The source of funding that supported the work, received from Scientific and Engineering Research Board (SERB), department of Science and Technology, GOI, New Delhi, India. Specific grant numbers: SB/S4/AS-134/2013 Initials of authors who received each award: Rakesh Kumar. Full names of commercial companies that funded the study or authors: No commercial funding was received. Initials of authors who received salary or 1. Introduction Damask rose (Rosa damascena Mill.) is considered as one of the important aromatic crops. The plant is highly valuable as it has application in perfumery, cosmetics and flavors industries. Besides this, it has application in pharmacology such as anti-HIV, antibacterial, antioxidant, hypnotic, antidiabetic activities [1] and is used to cure depression, insomnia and for stress PLOS ONE | https://doi.org/10.1371/journal.pone.0214672 April 4, 2019 1 / 14 Effect of shade level and mulch type on growth, yield of damask rose (Rosa damascena) other funding from commercial companies: No salary was received from commercial funding. URLs to sponsors’ websites: http://www.dst.gov. in. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. reduction [2]. Bulgaria, Turkey, Morocco, Iran, India, Egypt, China, and Russia are known to produce damask rose for producing rose oil, rose water, concrete, attar and absolute [3]. The price of its essential oil varies from 7 to 10 lakh kg-1 [2]. The quality of essential oil of damask rose is due to the high percentage of the monoterpene alcohols such as citronellol, trans-geraniol, linalool, phenyl ethyl alcohol and hydrocarbons such as nonadecene and nonadecane. The growth and yield of damask rose are affected by agronomic factors viz., nutrient management, varieties, harvesting stage, distillation process, diurnal variability and storage conditions of flowers. Light is one of the most important environmental factors for plant growth and development [4]. Different light intensities influence plant growth, leaf gas exchange, and water use efficiency. In aromatic crops, different light intensities have been demonstrated to alter essential oil content and composition. The substantial amount of light energy is required to reduce carbon which combines with CO2 producing oxygen, carbohydrates, ATP and NADPH. The sugars converted into amino acids, hormones, and secondary metabolites. However, plants grown under shade level leads to reduce the stomatal conductance, photosynthesis rate, ATP synthesis, carbon assimilation and plant growth [5,6]. The study of microclimate modification by using different green shade nets found that different crops behaved differently under shade conditions [7]. These variations in the microclimate modify the rate of CO2 assimilation and photosynthesis, consequently, crop growth and productivity. Crop yield and productivity can also be increased by application of mulch in the soil as it improves soil conditions for plant growth, including soil temperature, soil moisture, weed control, reduction in leaching of fertilizers [8]. Mulching is also known to buffer soil temperature, increases early production and higher yields along with better quality; enhance water and fertilizer use efficiency and decrease the incidence of pests [9]. Therefore, different types of mulching materials are used to change the micro environment along with the improvement of crop growth and yield. Plant acclimation to different light intensities depends on environmental conditions and plant genotype, and thus is species-specific [10,11]. There is a dearth of information on shade effect and mulch type for the production of damask rose in the world. Modification of microclimate by shade and mulch is an alternative approach to meet the increasing demand of damask rose under such condi (...truncated)