Physiological and Biochemical Responses of Cotton (Gossypium hirsutum L.) to Manure and Chemical Fertilizer on Saline and Non-saline Soils

This study evaluated the effects of chemical and organic fertilizer on the growth parameters, photosynthetic pigments, proline, total soluble carbohydrates, total phenol, flavonoid, and anthocyanin contents of cotton plants grown on saline and non-saline soils. The experiment used ‘Candia’ cotton cultivar, with fertilizer treatments including control, control + Triple Super Phosphate (TSP: P Source, 200 kg TSP ha⁻¹), manure (100 Mg ha⁻¹), and diammonium phosphate (DAP) + urea (200 kg DAP ha⁻¹ + 200 kg urea ha⁻¹). The fertilizers were mixed with 5 kg of soil per pot, and their effects on plant physiological and biochemical parameters were measured. The highest chlorophyll a content was recorded for DAP + urea treatment (12.31 mg g⁻¹) on non-saline soil (13.41 mg g⁻¹). Manure and DAP + urea significantly increased chlorophyll a and b levels, while control + P and DAP + urea enhanced carotenoid content, which supports antioxidant defense mechanisms. Plants grown in saline soils exhibited lower phenol and proline content compared to those grown on non-saline soil. The DAP + urea also resulted in the highest anthocyanin content. Manure and DAP + urea positively influenced cotton growth and photosynthesis, mitigating some of the negative impacts of salinity on plant physiology. These practices can offer sustainable benefits to agro-ecosystems, improving soil health and productivity in saline environments.