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

Why smarter watering of broccoli matters

Broccoli is packed with nutrients, but growing it in dry regions can demand a lot of precious water and fertilizer. This study from New Delhi asks a practical question with big stakes for farmers and food prices: how little water can you use, and how should you combine it with nitrogen fertilizer, to still harvest healthy broccoli while wasting less water and money? The answers point to simple adjustments that can boost yields and protect limited water supplies in semi-arid areas.

Testing different ways to water and feed the crop

The researchers ran a two-year field trial on a research farm in Delhi, which has hot, dry summers and cool winters. They grew a popular sprouting broccoli variety under drip irrigation, a system that delivers water directly to plant roots through narrow tubes. They compared three watering levels that kept soil at full, three-quarter, or half of its water-holding capacity, and combined these with four nitrogen fertilizer levels, from half the usual recommendation to one-quarter above it. By tracking plant height, leaf growth, head size, and final yield, they could see how each combination affected crop performance.

How plants responded to water and nitrogen

During the first month after transplanting, broccoli plants looked similar regardless of treatment. Differences emerged later, as plants with more water and nitrogen grew taller, produced more leaves, and formed denser canopies that captured more sunlight. Full irrigation together with the highest nitrogen rate produced the longest and heaviest central heads and the most numerous side shoots. Compared with the driest treatment, fully watered plots produced roughly one-half more side-shoot yield and around one-sixth more central head yield, showing how strongly moisture levels shape broccoli growth in a dry climate.

Balancing yield with careful water use

While full irrigation and extra nitrogen gave the highest total yield and biomass, the team also asked how efficiently the crop turned water into food. They calculated water use efficiency, which reflects how much broccoli is harvested per unit of water used by the plants, and irrigation water productivity, which focuses on water applied through the drip system. Here, a slightly different picture emerged. A moderate watering level combined with the highest nitrogen rate gave the best water use efficiency, meaning the plants produced more broccoli for each unit of water they actually consumed. In contrast, the driest treatment used the least irrigation water and therefore gave the highest return per unit of water applied, but at the cost of noticeably lower yields.

What this means for farmers and dry regions

Overall, the study shows that both water and nitrogen must be managed together to get robust broccoli yields and sensible use of scarce water. For farmers aiming for maximum production in semi-arid areas, full irrigation with slightly higher-than-standard nitrogen gave the strongest growth and highest yields. For those who need to stretch limited water supplies, a modest reduction in irrigation, paired with a generous nitrogen supply, delivered nearly comparable yields with better water use efficiency. By using drip irrigation and tuning fertilizer rates, growers can raise more broccoli per drop, improving incomes while easing pressure on overdrawn water resources.

Citation: Rajput, J., Singh, M., Lal, K. et al. Optimizing water use efficiency of sprouting broccoli through irrigation and nitrogen management under drip irrigation in semi-arid condition. Sci Rep 16, 14844 (2026). https://doi.org/10.1038/s41598-026-39272-2

Keywords: broccoli, drip irrigation, water use efficiency, nitrogen management, semi arid agriculture