Biochemical Response of Plant and Soil to Varied Levels of Nitrogen and Penoxsulam Application in Rice Crop

Nutrient management and chemical weed control are the two important aspects in crop production. The interaction between nitrogen (N) fertilizer application and penoxsulam on the biochemical properties of rice plants and soil properties is still to be explored under sub-tropical conditions. Rice was grown for two seasons (2020 and 2021) with three levels of N (100, 125, and 150% of recommended dose) and three levels of penoxsulam 2.67% oil dispersion (OD) (0, 1000, and 2000 ml ha −1 ). Plant and soil samples were collected at different growth stages of the crop. Plant samples were analyzed for chlorophyll a, chlorophyll b, total phenolic activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, and total nutrients. Soils from the respective plots were also analyzed for available nutrients and soil enzyme activities. Increased application of nitrogen improved chlorophyll pigments in rice, and the effect of penoxsulam on these pigments was negatively correlated. In contrary, penoxsulam increased the total phenolic content of rice leaf. The interaction of N and penoxsulam indicated an enhanced proline level in rice. Available nutrients in rice soils were increased with increasing application of N. The effect of N fertilization on soil enzymatic activities was positive, but declines with the application of penoxsulam. In rice grains, amylose content was decreased with N levels and increased with penoxsulam concentration. The highest rice yield was obtained with 125% N coupled with double the recommended dose of penoxsulam. Application of nitrogen (125%) coupled with 1000 ml ha −1 penoxsulam alters biochemical responses in plant and soil, which paved acceptable yield and grain quality.