Exogenously Applied Bio-Stimulant and Synthetic Fertilizers to Improve the Growth, Yield and Fiber Quality of Cotton

Abstract

The effects of exogenously applied Moringa oleifera leaf extract (MLE), nitrogen and potassium were studied on the productivity and quality of two cotton cultivars (CIM-573) and transgenic Bt cotton (CIM-598). The Randomized Complete Block Design (RCBD) factorial experiment was conducted at Bahauddin Zakariya University, Multan, Pakistan (30.2639 °N, 71.5101 °E; 123 m asl), during 2016 and 2017, with three replications. The analysis of variance revealed the significance of cotton cultivars and foliar applications for the majority of traits studied, in both years. The CIM-573 had superiority for most of the traits studied in 2016 and 2017 trials, while the CIM-598 cultivar had significantly higher record for chlorophyll content, seed cotton yield, mean boll weight, and seed index in 2016 and sympodial branches per plant in 2017. Foliar application of Moringa Leaf Extract (MLE) and synthetic fertilizers showed significant differences for the traits studied compared to the distilled water. Exogenous application of MLE has a positive effect on photosynthetic and enzymatic activities that improve the efficiency of nutrients that are utilized, thereby improving the growth, seed cotton yield and quality of cotton cultivars tested. All the interaction effects had a significant influence on the traits studied, except ginning percentage in 2016. The interaction between the conventional cotton cultivar (CIM 573) and exogenous application of MLE + nitrogen + potassium had significantly higher effect on plant height, cotton yield, staple length, fiber maturity, and fiber strength for the 2017 trial and was superior for the quality parameters in 2017. The interaction of the Bt cotton cultivar (CIM 598) and the foliar application of MLE + nitrogen + potassium had superiority in cotton yield, yield components and the quality parameters in the 2017 trial. Both the CIM 573 and CIM 598 cotton cultivars had consistent expressions for all quality traits studied, although they did fluctuate in their expression to these agronomic traits between the field trials of 2016 and 2017. Additive gene effects could be the explanation for the unstable effects of yield and the related traits in the different environmental conditions of the field trials in the two years. Our results suggest that the exogenous application of MLE alone and in combination with nitrogen and potassium could be used to improve the productivity and the quality of these cotton cultivars. The correlation coefficients indicate strong associations between the agronomic and quality traits, indicating that one or more yield parameters could be used as selection criteria to improve the productivity and quality of cotton.