Study the effects of humic acid and salicylic acid application on yield, fiber quality and nutrient concentration in leaves of cotton var. Khordad

In order to investigate the effects of humic acid and salicylic acid on quantitative and qualitative properties and nutrients concentrations in leaves of cotton var. Khordad, a two-year field experiment were conducted at the Tehran Agricultural  and Natural Resources Research  and education Center during 2018with randomized complete block  design as factorial with two factors as follow: soil application of humic acid at three levels (zero, seed coated and 10 L/ha as fertigation) and foliar application of salicylic acid at three levels (zero, 2 mM and 4 mM as foliar application), with a total of 9 treatments. The effect of humic acid, salicylic acid and their interaction on yield and yield components, leaf chlorophyll content, concentration of macronutrients in leaves and fiber quality were significant. The highest seed cotton yield (4409 Kg.ha-1) was obtained from the combined application of humic acid in the form of seed coated and salicylic acid in the form of foliar application at a concentration of 4mM that was 49% higher compared to the control Application of humic acid and salicylic acid improved the qualitative characteristics of the fibers, so that the maximum average fiber length of cotton fibers was 31 mm from the combined application of humic acid as seed coated and salicylic acid as foliar spraying with concentration of 4mM  was obtained, which was a 10.7% increase in length compared to the control treatment (without the use of humic acid and salicylic acid). The interaction of humic acid and salicylic acid on the mean concentration of nitrogen, phosphorus, potassium, calcium, magnesium in cotton leaves was significant. In this regard, the highest mean concentrations of nitrogen, phosphorus, potassium, calcium and magnesium of cotton leaves were 3.9, 0.43, 3.9, 1.6 and 0.99%, respectively, from the combined application of humic acid to Seed and salicylic acid were obtained by spraying at a concentration of four per thousand, which compared to the control treatment (without the use of humic acid and salicylic acid), respectively for nitrogen, phosphorus, potassium, calcium and magnesium. 44, 53, 62, 60 and 12% more. Based on the results obtained from this study, the application of humic acid in the form of seed coated and salicylic acid in the form of foliar application in saline conditions, modulates the effects of salinity stress and increases the yield of cotton and improves the quality characteristics of fibers