Influence of post-vegetative foliar application of nitrogen and selenium on micrometeorological parameters, phenology, and yield of wheat (Triticum aestivum L.)

Excessive and continuous use of commercial-grade fertilizers in large quantities during the post-Green Revolution era has led to significant environmental impacts, besides escalating the cost of production in staple crops. Such over-reliance on chemical fertilizers in intensive agriculture and a limited focus on balanced nutrient management have led to an increase in micronutrient deficiency in the sub-tropical part of India. This micronutrient deficiency leads to stunted growth, poor flowering, and reduced grain and fruit formation, directly impacting overall crop productivity. Hence, the introduction of nano form of fertilizers and integration of them with bulk/commercial form will help in improving the nutrient use efficiency, reduce production costs vis-a-vis enhancement in the plant growth, and yield more effectively than the traditional fertilizers. Proper nutrient management promotes healthy development at each stage, from seedling establishment to maturation and ripening, ensuring optimal yields and quality. Hence, fertilization directly and profoundly impacts the phonological stages of the crops. In this respect, a field experiment was conducted at Ludhiana and Fatehgarh Sahib, Punjab, India, during the rabi season of 2021-22. The experiment was laid out in a Randomized Completely Block Design (RCBD) with four replications and 11 treatments. Besides an absolute control where no fertilizer was applied (T1), ten other treatments were commonly fertilized with the recommended dose of fertilizers (RDF), i.e., 125 kg N and 62.5 kg P2O5 ha-1). The treatment varied in applying bulk and nano N (6% urea) and Se (15 ppm) at reproductive phases. The normalized difference vegetation index (NDVI) score and chlorophyll index improved with foliar spray of both bulk and nano urea forms alone or in combination with Se (bulk or nano). The effect of foliar sprays of urea and selenium, either in bulk or nano form, alone or in combination, was insignificant. The reproductive stages, viz. heading, grain filling, and physiological maturity, are prolonged with late season spray of 6% bulk or nano urea alone or in addition to bulk or nano selenium. Maximum days to grain filling was in a foliar spray of nano urea 6% along with nano selenium 15 ppm, further leading to higher grain and biological yield.