Optimizing water use efficiency of sprouting broccoli through irrigation and nitrogen management under drip irrigation in semi-arid condition.

Broccoli is a high-value vegetable, and its potential production can be achieved with appropriate irrigation and nutrient management strategies, as adequate moisture and nitrogen availability in the crop root zone are essential for an optimal yield. Also, irrigation and nitrogen levels have significant effects on broccoli yield, biomass production, and water productivity. Therefore, field experiment was conducted to assess the response of broccoli (Brassica oleracea L. var. italica Plenck) cultivar Palam Samridhi at the research farm, Water Technology Centre, Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, India, during Rabi seasons in 2016–17 and 2017–18. The field experiment was laid out in split plot design of experiment methods with three irrigation levels viz., full irrigation (100% of field capacity (FC) (I1), 75% of FC (I2), and 50% of FC (I3) and four nitrogen levels viz., 50% of recommended dose of nitrogen (RDF) (N1), 75% RDF (N2), 100% RDF (N3), and 125% RDF (N4). The crop growth and yield attributes were analyzed statistically at 5% level of significance. The results revealed that the plant growth parameters viz., plant height, number of leaves and leaf area index did not show a statistically significant variation at 30 days of transplanting (DAT), however, all these three were found to be significant at 60 DAT and at harvesting of the crop. It was found that the irrigation and nitrogen levels had significantly influenced the broccoli head length, head diameter and head weight. As compared to irrigation treatment I3, the auxiliary shoot and head yield was increased by 47.87 and 16.89% in 2016–17, and 46.49 and 15.50% in 2017–18 in full irrigation level (I1). In both 2016–17 and 2017–18 crop seasons, increasing the nitrogen level from N1 to N4 resulted in significant improvements in auxiliary shoot and central head yield. Total yield and harvest index showed statistically significant variability under irrigation and nitrogen levels. The water use efficiency (WUE) and irrigation water productivity (WP) were increased by 20.32 and 19.86% by increasing nitrogen level from N1 to N4, and 9.86 and 54.79% by increasing the irrigation level from I3 to I1, respectively in 2016–17. Similarly, in 2017–18, the WUE and WP increased by 19.20 and 20.35% by increasing the nitrogen from N1 to N4, and 12.11 and 44.75%, by increasing irrigation level from I3 to I1, respectively. The study revealed that all the crop growth and yield attributes were found to be best under I1N4 treatment. Irrigation levels effect was more than the nitrogen levels effect on the crop growth and yield parameters. The interaction effects of the irrigation and nitrogen levels on yield was found non-significant (5%). The water use efficiency was found to be the best in I2N4 treatment. The study found that proper irrigation and nitrogen management significantly improve WUE in broccoli cultivation. The I2N4 treatment resulted in the highest WUE, demonstrating that deficit irrigation with increased nitrogen supply can improve water productivity.