Impact of Jasmonic Acid on Sugar Yield and Physiological Traits of Sugar Beet in Response to Water Deficit Regimes: Using Stepwise Regression Approach

A field study on sugar beet with foliar application of jasmonic acid (JA) was evaluated under deficit irrigation regimes. The experiment was carried out in randomized complete block design with three replicates at two locations (Shahrekord and Shalamzar) in Chaharmahal-Bakhtiari Province, Iran during 2015 growing season. The experiment applied JA on sugar beet (Beta vulgaris L.) at two different concentrations of 5, 10 mu M and control (foliar with water) under three water requirement of sugar beet (100, 75 and 50%). Physiological parameters of the sugar beet such as proline, soluble carbohydrates, chlorophyll content, carotenoid, anthocyanin, membrane stability index, root sugar content, root yield and sugar yield were evaluated. The results revealed water deficit led to decreases in carotenoid, chlorophyll content, relative water content, membrane stability index, root yield and sugar yield while proline and root sugar content increased significantly. Foliar application of JA resulted in notable improvements in the mean of all traits. JA amendment positively affected plant water relations mostly due to enhancements in osmoregulation. Ameliorative effects of exogenous JA tended to be greater in drought-stressed sugar beet plants as it led to the enhancement of chlorophyll content and relative water content in water deficit conditions. The results in this study demonstrated that the foliar application of JA significantly mitigated detrimental effects of water stress in sugar beet with increased root sugar content and sugar yield under water deficit regimes.