The effect of seed treatment with salicylic acid, humic acid and zinc on the yield of durum wheat under rainfed conditions

Introduction: Nowadays, seed treatment with growth regulators or nutrients is widely used in the seed industry due to its significant effect on growth and yield, as well as resistance to diseases and pests. Therefore, in the present research, the effects of seed treatments with salicylic acid, humic acid, and zinc on two durum wheat cultivars were investigated under rainfed conditions.Materials and methods: This research was conducted as a factorial experiment based on a randomized complete blocks design (RCBD) with three replications in the research farm of the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran, in 2019-2020. Factors included two cultivars of durum wheat (Saji and Zahab) and seed treatments (salicylic acid, humic acid, zinc, salicylic acid + humic acid, salicylic acid + zinc, humic acid + zinc, salicylic acid + humic acid + zinc, and control). Seed treatments were applied before sowing with a concentration of one millimolar (mM) salicylic acid solution, zinc solution (2%), and humic acid powder (95%) at the ratio of one kg or lit to 100, 100, and 300 kg of seeds, respectively. The investigated traits included the content of photosynthetic pigments and flag leaf area in the boot stage (code 45 on the Zadoks growth scale) and yield and yield components and seed protein percentage at the ripening stage.Results: The results of the analysis of variance showed that the effect of cultivars, seed treatments, and interactions between them was significant on the studied traits (except the number of spikes per square meter). The grain yield in durum wheat cv. Zahab was significantly higher than Saji. The grain yield of two cultivars in all seed treatments was higher than the control. Grain yield in Zahab was almost the same in all of the seed treatments, but in Saji, the highest grain yield was obtained in seed treatment with zinc usage (5033 kg. ha-1), and other seed treatments had the same effects. There was no significant difference between the two cultivars in terms of seed protein percentage, but the highest and lowest amount of seed protein was observed in salicylic acid + humic acid and control seed treatments with 13.14 and 12.11%, respectively. At the boot stage, the effects of cultivar and seed treatment on flag leaf area and the content of photosynthetic pigments (except carotenoids) were significant. Zahab cv. was superior to Saji in terms of flag leaf area and photosynthetic pigment content.Conclusion: Based on the results of this research, durum wheat cv. Zahab had a better performance than Saji. The effect of seed treatments with salicylic acid, humic acid, zinc, and the combination of these treatments had positive and significant effects on the grain yield compared to the control.