M.A. Thesis:

Morphophysiological response of cotton to amount and split application of potassium in saline conditions

Potassium (K) plays an essential role in reducing the effects of salt stress in plants. The effect of rate and application method of potassium on growth and morphology of cotton in saline soil was studied as out as split plot design based on randomized complete block design with three replications in Sabzevar Agriculture and Natural Resources Research center in 2015.. Factors were: K rate (75 and 15 kg ha-1 K20 (Solopotash form(50% k20 and 18% S)) as the main plot and application method (25 at planting+25% at first flowering and 50 at early boll development (25P+25F+50B), 25 at planting+50% at first flowering and 25 at early boll development (25P+50F+25B), 25 at planting+25% at vegetative stage (5-8 leaves stage), 25% a first flowering and 25 at early boll development (25P+25V+25F+50B) 25 at planting+25% at vegetative stage and 50% a first flowering (25P+25V+50F) and 25 at planting+50% at vegetative stage and 25 at early boll development (25P+50V+25B) as the subplot. Plant height, No, of vegetative branches, No, of sympodial branch, chlorophyll index, Seed per boll and Seed weight did not affect by potassium rate. K application as 25 at planting+25% at vegetative stage (5-8 leaves stage), 25% a first flowering and 25 at early boll development (25P+25V+25F+25B) had the highest chlorophyll index. While K applies as 25P+25V+50F had the highest No, of vegetative branches, Seed per boll and Seed weight. Increasing of K level to 150 kg.ha-1 increased boll weight, seed cotton yield, Seed cotton yield and biological yield compared than 75 kg.ha-1 . Plant height, sympodial branch number and lint percentage did not respond to K rate. K application as 25 at planting+25% at vegetative stage (5-8 leaves stage), 25% a first flowering and 25 at early boll development (25P+25V+25F+25B) had the highest boll weight, seed cotton yield, biological yield and lint percentage. In both K rate split application of K at planting, vegetative stage, flowering and early boll development (Equally at each stage) had the highest seed cotton yield. K application at flowering or early boll development had more positive effect on seed cotton yield compared than planting or vegetative stage. The results obtained here suggest that 150 kg.ha-1 application (as Solopotash form) equally a planting, vegetative stage, flowering and early boll development can improve the seed cotton yield grown under saline condition.

Keywords: Cotton yield, Salinity, Potassium split application, Cotton