Foliar application of nanoboron fertilizer at different growth stages enhanced the nutrient use efficiency of cauliflower, leading to improve productivity, quality, and profitability

Boron (B) is an essential element for the production of cauliflower ( Brassica oleracea var. botrytis ); nevertheless, conventional soil or foliar applications frequently suffer from inadequate nutrient uptake and leaching. Nano-boron fertilizers offer a highly efficient alternative due to their small particle size and superior surface-to-volume ratio, which enhances cellular penetration. This study aimed to determine the optimal dose of a foliar application of boron nanoparticles (B-NPs) and to compare the effects of conventional boron (B) and boron nanoparticles on the growth, yield, quality, nutrient dynamics, and profitability of cauliflower. A field experiment was conducted using a randomized complete block design with 5 treatments involving four concentrations of boron nanoparticles (0, 100, 200 and 300 ppm) and conventional boric acid@1 gL − 1 . Foliar sprays were applied at 30 and 45 days after transplanting. Foliar application of 200 ppm boron nanoparticles resulted in the highest fresh curd yield (50.2 t ha − 1 ), which was 69.6% greater than that of the control and 23.3% greater than that of the conventional boron treatments. This improvement was driven by the superior curd size and an individual curd weight of 1761 g. The same treatment significantly enhanced the quality parameters, yielding the highest vitamin C content (46.9 mg/100 g), protein content (25.1%), and curd firmness (1.23 kgf). This dose also resulted in the highest total B uptake (0.299 kg ha − 1 ), maximum agronomic efficiency (45.9 kg g − 1 ), and apparent recovery efficiency of B (356%). Economically, the 200 ppm nanoboron application proved most viable, achieving the highest benefit‒cost ratio of 4.14. The results suggest that the foliar application of 200 ppm B nanoparticles can be used for sustainable cauliflower cultivation. However, this method is a highly effective and suitable approach for optimizing cauliflower productivity and quality in B-deficient environments.