Composite analysis of the effect of potassium sulphate foliar application on the amount of tissue elements and the yield of cotton genotypes under saline irrigation conditions

Background and objectives: Saline conditions and especially saline water can interfere with the uptake of ions by plants and lead to a decrease in crop yields. On the other hand, the application of potassium sulfate under these conditions reduces the negative effects of salt stress and leads to an increase in crop yield. Therefore, this study was conducted to investigate the effects of saline water irrigation on ionic ratios and yield of cotton in a two-year trial at Rudasht Salinity Research Station, Isfahan.
Materials and methods: This experiment was conducted as a factorial split-plot design with four replications in a randomized block design. In this experiment, main plots include irrigation treatments of 4 (control), 8 and 12 ds.m-1 and sub-plots include factorial combination of three genotypes (mutant genotype LM 1673, LM 1303 and Shayan) with foliar sprays of potassium sulfate at three rates of 2, 4 and 6 kg per 1000 liters of water per hectare with control treatment.
Results: The results showed that the effect of salinity treatments and cultivar and the interaction effect of year*salinity*number of spray solutions were significant on the amount of calcium in stems and leaves, chlorine in stems and leaves, potassium in stems and leaves, sodium in stems and leaves, and yield. The effect of potassium sulfate foliar spraying on calcium in stem, chlorine in leaf, potassium in stem and leaf, sodium in stem and leaf, and yield was also significant. In the two experimental years, increasing the salinity of the irrigation water resulted in an increase in the content of elements such as calcium, sodium and chlorine in the stems and leaves, but a decrease in the content of potassium. The results showed that in the first year of the experiment, the highest calcium content in the stem occurred with 4.1 mg.g-1 when treated with an irrigation salinity of 12 ds.m-1 in the genotype LM 1303 and a foliar spray of 6 kg.ha-1 potassium sulfate. In the second year, the amount of calcium in stem and leaf tissue of cotton was obtained in irrigation treatment with water with salinity 12 ds.m-1 and variety LM 1303 in foliar treatment with 4 kg.ha-1 potassium sulfate (3.16 mg.g-1) and foliar application of 6 kg.ha-1 potassium sulfate (4.33 mg.kg-1), respectively. In the first year of the experiment, the highest chlorine content in the stem was 23.4 mg.g-1 under irrigation conditions with saline water of 12 ds.m-1 and in the cultivar LM 1303 with foliar spray of 4 kg.ha-1 potassium sulfate. In the second year, the chlorine content of the cotton stem and leaves was measured when irrigated with water with a salinity of 12 ds.m-1 and the variety LM 1303 when foliar treated with 4 kg/ha of potassium sulfate (3.23 mg.g-1) and the solution spraying of 6 kg.ha-1 of potassium sulfate (5.92 mg.kg-1), respectively. In both years, potassium content in stems and leaves decreased with the increase in salinity of irrigation water, while foliar application of potassium sulfate led to its decrease. In the first and second year, the highest cotton yield of 3918 and 3696 kg ha-1, respectively, was obtained with genotype LM 1303 at salinity of 4 ds.m-1. Foliar application of potassium sulfate also increased the yield of sorghum, so that the highest yield of 3016 kg.ha-1 was obtained with application of 6 kg.ha-1 potassium sulfate.
Conclusion: The results show that the yield of genotype LM 1303 increased under saline and non-saline conditions by foliar application of potassium sulfate. Therefore, it can be said that the variety LM 1303 and foliar application of potassium sulfate can be used to improve ionic ratios in cotton and obtain the highest cotton yield under saline conditions in the region.