Impact of drip irrigation scheduling and nitrogen levels on nitrogen use efficiency, phenology and soil nitrogen dynamics of okra (Abelmoschus esculentus L.)

Abstract

A field experiment was conducted at Water Technology Centre, College of Agriculture, PJTSAU, Rajendranagar, Hyderabad during summer 2020-21 on “Optimization of irrigation and nitrogen levels under drip fertigation in okra (Abelmoschus esculentus L.) during summer” 2020-21. The experiment was laid out in a split-plot design with Radhika hybrid (40 cm x 45 cm) and replicated thrice. The treatments comprise of three irrigation levels through drip scheduled at 0.75 Epan, 1.0 Epan and 1.25 Epan as main-plots and four nitrogen levels viz., 75 % RDN (112.5 kg N ha^-1), 100 % RDN (150 kg N ha^-1), 125 % RDN (187.5 kg N ha^-1) and 150 % RDN (225 kg N ha^-1) as sub-plots. Experimental soil was sandy clay in texture, alkaline in reaction, medium in organic carbon content, low in available nitrogen, high in available phosphorous and available potassium, respectively. The results indicated that optimized drip irrigation scheduling significantly improved NUE, with the highest efficiency observed at 1.00 Epan (I2) irrigation scheduling and 75 % RDN (N1) nitrogen level. Phenological development, including days to first flowering, days to 50 % flowering, days to first and final picking was not influenced influenced by irrigation scheduling and nitrogen supply. The number of branches per plant increased with 1.00 Epan (I2) and 100 % RDN (N2) nitrogen application, contributing to higher biomass and potential yield. Soil nitrogen content varied across treatments, with initial and final measurements providing insights into nitrogen uptake and residual soil fertility.