Estimation general combining ability of fruit yield, essential oil content and physiological traits related to drought stress tolerance in coriander through polycross method

IntroductionCoriander (Coriandrum sativum L.) is an annual herb of the umbel family and is belonged from North Africa to south-western of Asia. Coriander is one of the important medicinal plant that used in the pharmaceutical industry and it mainly cultivated and widely distributed for the fruits. The dried fruits are widely employed as a condiment, especially for flavoring of sauces, meat products and bakery and confectionery items. Also, coriander fruits are as a source of essential oils and fatty oil. Water deficit stress is one of the most important factors limiting the growth and survival of plants in arid and semi-arid regions of the world. Water is a major component of the fresh produce and significantly effects on weight and quality of plants. Also, water deficit may cause significant changes in the yield and composition of essential oils in aromatic and medicine plants. So that, was reported that water deficit increased essential oil percentage in coriander but decreased essential oil yield. Iran with an average annual rainfall of 240 mm is included among arid and semi-arid regions of the world. Of the million hectares of cultivated region, only five millions are under irrigation because of intense water limitations. However, Iran is one of the world’s commercial coriander producers. Coriander has been cultivated for many years in different parts of Iran. Therefore, development of drought-tolerant cultivars with high essential oil yield is important in coriander. The objective of this study was evaluation general combination ability of endemic coriander genotypes for fruit yield, yield components and essential oil content under different watering regimes.Materials and MethodsF14 half sib families including TN-59-10, TN-59-36, TN-59-80, TN-59-158, TN-59-160, TN-59-164, TN-59-230, TN-59-306, TN-59-347, TN-59-353, TN-59-357, TN-59-422, TN-59-450 and commercial genotype were evaluated in randomized complete block design with three replications in each experiment during growing season of 2016 in the research field of Tarbiat Modares University. Plants were treated with different levels of water treatment: well watered (WW), moderate water stress (MWS) and severe water stress (SWS).Results and DiscussionResults of data analysis revealed that total chlorophyll (86.32%), fruit yield (98.56%) and essential oil content (48.85%) exhibited the most phenotypic coefficients of variation in non-stress, moderate stress and severe stress conditions, respectively. Also, the most genotypic coefficients of variation in non-stress, moderate stress and severe stress estimated for essential oil content (79.86%), fruit yield (43.76%) and essential oil content (45.5%) respectively. Results of cluster analysis using general combining ability (GCA) data revealed that F8, F9, F10 and F14 are suitable for synthetic variety production to cultivate in full irrigated condition because these genotypes had high GCA for fruit yield and its component. F1, F7 and F11 are suitable to produce high fruit and essential oil yielding variety in moderate drought stress. Also, F6, F7, F11, F13 and F14 suggested as donor for fruit yield and F1, F3, F7, F9 and F12 for essential oil content in severe drought stress.ConclusionGenerally, the results indicated that that F8, F9, F10 and F14 are suitable for synthetic variety production to cultivate in full irrigated condition because these genotypes had high GCA for fruit yield and its component. F1, F7 and F11 are suitable to produce high fruit and essential oil yielding variety in moderate drought stress. Also, F6, F7, F11, F13 and F14 suggested as donor for fruit yield and F1, F3, F7, F9 and F12 for essential oil content in severe drought stress.AcknowledgementsThe authors thank from the Gene bank of the Seed and Plant Improvement Institute of Karaj, Iran for making available plant materials