Effect of Foliar Application of Salicylic Acid on Yield, Yield Components and Essential Oil of Fenugreek (Trigonella Foenum-Graecum L.) under Water Deficit Conditions

Salicylic acid is an important signal molecule modulating plant responses to abiotic (drought) stresses. A pot factorial experiment based on completely randomized design with three replications was carried out to investigate the effect of salicylic acid on yield and essential oil content of fenugreek under water deficit conditions. Factors were two irrigation levels (50 and 100% of field capacity) and four salicylic acid doses (0, 0.5, 1 and 1.5 mM). Results showed that interaction effect of water stress levels and salicylic acid doses was significant (P≤0.01) for number of pods per plant, 1000-seed weight, protein percent, proline and total soluble sugars. Maximum grain yield (119.2 g/m2) was obtained with application of 1.5 mM salicylic acid and water deficit stress showed significant difference with respect to optimum irrigation. Maximum protein percent (13.83%) was obtained under water deficit conditions and without application of salicylic acid. There was no difference in essential oil percent in 1 mM foliar application of salicylic acid between optimum irrigation (1.4%) and water deficit conditions (1.44%). Therefore, with respect to different responses of studied traits to different levels of salicylic acid, it could be concluded that salicylic acid is able to reduce and adjust the negative effects of water deficit stress on fenugreek plant.