Effect of silicon foliar application on yield and some physio-chemical properties of fennel under limited irrigation

In this study, the effect of drought and different concentrations of silicon was examined on seed yield, essential oil percentage and physio-chemicals properties in fennel plant. The experimental design was a split plot with three irrigation regimes: irrigation at 100, 70 and 40 percent of FC comprising the main treatments, and five levels of silicon foliar sprays (0, 2.5, 5, 7.5 and 10 mM) as sub-treatments that were applied with three replications. The experiment was conducted in 2014 at the Zabol University research farm in Zabol, south Iran. Limited irrigation significantly decreased chlorophyll, carotenoids, leaf relative water content, while electrolyte leakage showed a 2 -fold increase over the control. In limited irrigation conditions 7.5 mM silicon increased relative water content, chlorophyll, antocianine, proline and soluble sugare by 38, 30, 38, 12 and 22 percent, respectively, while decreased electrolyte leakage by 28 perent over the control. These results suggested that silicon spraying by photosynthetic pigments and soluble osmolytes increasing could increase the ability of plants to drought stress, and in this way increased seed yield by 61 percent under severe stress conditions.