Simultaneous effect of water deficit and mating systems in fennel (Foeniculum vulgare mill.): Genetics of phytochemical compositions and drought tolerance

Limited information is available on the impact of deliberate selfing compared with open-pollination and its interaction with water deficit on productivity and phytochemical constituents of essential oil in fennel (Foe-niculum vulgare Mill.) and also the genetic analysis of traits. During this research, 21 selfed (S1) and 42 open pollinated (OP) progenies of fennel developed in 2017-18 were evaluated in the field under well-watered and water deficit conditions in two years (2019 and 2020) for phytochemical and productivity traits. GC-MS analysis revealed that among the eight different compounds in the essential oil, trans-anethole, fenchone, estragole, and limonene were found to be the main constituents. Water deficit greatly decreased grain yield and essential oil content, alpha-pinene, trans-anethole, and anisaldehyde; while significantly increased ll-myrcene, limonene, gamma-terpinene, fenchone, and estragole, in both populations. Compared with open-pollination, selfing reduced the mean performance of seed and essential oil yield, ll-myrcene, and limonene under normal and water deficit conditions, and alpha-pinene under normal condition, demonstrating the effects of inbreeding on these traits. The relationship between gamma-terpinene and anisaldehyde was positive in the S1 population; while in the OP population, there was significant and negative association between these two constituents. The genetic analysis of traits indicated that additive gene action played an important role in controlling most of the traits, but that both additive and non additive gene effects played a role in the genetic control of grain yield; indicating that selection based on an index may be more useful for improvement of grain yield in recurrent selection programs.