Effect of different sources of Phosphorus Fertilizers addition on growth performance, productivity and Bulb Quality of Onion Plants

Onion is regarded as a highly valuable vegetable crop due to its rich nutritional content; however, insufficient phosphorus application remains a major limiting factor in achieving optimal yields. Investigation into how onions respond to different phosphorus sources can help enhance fertilizer formulations, promoting more sustainable agricultural practices with reduced environmental impact and improved market competitiveness. Therefore, two open field experiments were conducted to assess the impact of various phosphorus sources (Phosphoric Acid, Brandt Reaction P DS, and Monoammonium phosphate) on the growth and production of onion plants in a randomized complete block design (RCBD) with four replications and four treatments. The obtained findings showed that maximum vegetative growth traits, like plant height, bulb diameter, fresh bulb, and dry bulb values were recorded to be higher in plants fertilized with Brandt Reaction P DS and Monoammonium phosphate, followed by phosphoric acid, while the minimal values were observed in unfertilized plants. Comparable trends were observed in the nutritional values of blub. Compared with the control treatment, the higher nutrients (N, P, K, Fe, and Zn), TSS, carbohydrate, protein content, and total phenol in bulbs of plants fertilized with Brandt Reaction P DS and Monoammonium phosphate, followed by phosphoric acid. The Principal component analysis showed that the exogenous addition of phosphorus has positive effects on the bulb yield and quality. Keywords: Allium cepa, Agro-physiological properties, phosphorus application, nutritional quality.