Foliar application of magnesium oxide nanoparticles on nutrient element concentrations, growth, physiological, and yield parameters of cotton

In order to investigate the effects of different magnesium (Mg) sources of fertilizers like magnesium sulfate (MgSO4), magnesium oxide (MgO), and magnesium oxide nanoparticles (nMgO) on cotton growth and development, a pot culture experiment was carried out at different concentrations viz., 20, 40, 60, 80, and 100 ppm in factorial completely randomized design (FCRD). From the pot culture studies, 60 ppm of nMgO was found as the optimal dose for improvement in SPAD chlorophyll value, boll weight, and seed cotton yield. Consequently, field experiment was carried out in randomized block design (RBD) with optimized dose of 60 ppm (from pot culture study) of Mg fertilizers like MgSO4, MgO, and nMgO to elucidate their effect on growth, physiological, yield, fiber quality parameters, and nutrient element concentrations in cotton. The treatments were foliar sprayed at vegetative and boll formation stages of cotton similar to pot culture studies. It is confirmed that foliar application of 60 ppm of 50 nm of MgO nanoparticles significantly increased the number of opened bolls per plant (20.6), single plant yield (58 g/plant) and seed cotton yield (1729 kg/ha). The increased seed cotton yield of 42.2, 39.9, and 24.8% was recorded by nMgO, MgO, and MgSO4 over control. Besides, fiber quality parameters like fiber length and fiber strength of cotton were improved by MgO nanoparticles than sulfate form of Mg fertilizers. Moreover, significant and positive influence was achieved by foliar nutrition of MgO nanoparticles on macronutrients like nitrogen (N), phosphorus (P), potassium (K), and Mg concentration in cotton plants.