SEED PRIMING WITH SALICYLIC ACID ENHANCED GAS EXCHANGES PARAMETERS AND BIOLOGICAL YIELD OF WHEAT UNDER LATE SOWING DATE

This experiment was done to evaluate the effect of two planting dates and salicylic acid (SA) on wheat photosynthesis. Wheat seeds, cv. Alvand, primed with SA (0, 400, 800, 1200, 1600, 2000 and 2400 μM) at two planting dates (recommended planting date, 23 October, and late planting date, 22 November). Gas exchange parameters were measured in three growth stages (tillering, heading and grain filling). The highest and lowest rate of photosynthesis (PN), stomatal conductance (gs) and transpiration rate (E) of plants were observed in heading and grain filling stages, respectively. Seed pretreatment with SA enhanced photosynthetic parameters and carboxylation efficiency (CE), but, intercellular CO2 concentration and water use efficiency (WUE) reduced by application of SA. It seems that application of SA had more effects on gs and E than PN. Among growth stages, the highest value of WUE was found in tillering and lowest in heading stage. Priming with SA compensated late sowing effects on plants PN. Chlorophyll content, chlorophyll a/b ratio and CCI values significantly increased in SA treated plants. Results show that priming with SA may reduce ameliorative effects of late sowing on wheat plant biomass production. Among SA concentrations, 1200 μM had highest value in both planting dates.