Enhancing Bok Choy growth through synergistic effects of hydrogel and different nitrogen fertilizer forms

The application of hydrogel to sandy soil has shown promise in enhancing crop production, offering alternative solutions to address the growing food demand. Here, we investigated the impact of hydrogel and different nitrogen (N) fertilizer forms (NH4+, NO3− and Urea) on Bok Choy (Brassica rapa var. chinensis) production through the evaluation of the plant growth parameters, photosynthesis, nutrient uptake, and soil physicochemical properties. Our findings reveal that the application of hydrogel significantly increased plant height (16.27 %), fresh weight (FW) (61.14 %), dry weight (DW) (65.69 %) weight, plant nutrient concentration, and uptake. Additionally, it improved photosynthetic parameters and induced alterations in soil physicochemical properties. The synergistic effects of hydrogel varied with different nitrogen forms, with NH4+–N fertilizer demonstrating the most efficiency in enhancing Bok Choy production (119.65 % FW) compared to control. Pearson correlation analysis established close associations between Bok Choy growth parameters, photosynthesis, nutrient accumulation, and soil physicochemical properties. Principal component analysis (PCA) underscored the significant influence of hydrogel and NH4+–N on various growth parameters in Bok Choy. The stimulated growth observed can be attributed to increased nutrient uptake, improved photosynthesis, and the maintenance of soil physicochemical properties. These findings carry significant implications for the practical application of hydrogel in the field, providing a valuable strategy to enhance nutrient use efficiency and crop production in sandy soil.