Onion is sensitive to soil water stress and nitrogen limitations, causing a marked reduction in yield and bulb quality. A field trial was set in the winter seasons of 2016–17 and 2017–18 to evaluate the effects of three micro-sprinkler irrigation levels at 0.6, 0.9 and 1.2 ratios of crop evapotranspiration (ETc) and four nitrogen levels at 0, 75, 100 and 120% of the recommended nitrogen dose (RDN), including surface irrigation at 40 mm cumulative pan evaporation (CPE) with 100% RDN (SN) using an augmented strip plot design on water and N distribution in soil, their productivities, onion yield and economics. Results indicated that the root zone water content increased by 5.2% for 1.2 ETc, and 1.4% for 0.9 ETc over the cropping period, but declined by 1.5% for 0.6 ETc with micro-sprinkler irrigation compared to surface irrigation with nitrogen fertilization (SN). The largest total root zone water depletion was in 1.2 ETc (16.7%), followed by SN (15.3%) and 0.9 ETc (15.0%). The high irrigation regime produced the maximum yield and nitrogen productivity, whereas deficit irrigation displayed the greatest water productivity. However, the coupling of micro-sprinkler irrigation at 1.2 ETc and 120% RDN led to an increase of onion bulb yield (22.6%), water productivity (42.7%), plant N uptake (29.0%) and net income (30.6%) with maximum benefit-cost ratio (3.19) compared to SN. However, as this study was only based on two seasons, more field trials will be needed to confirm the optimum amount of water and nitrogen for winter onion.

Water scarcity due to global warming can increase the water demand for upland rice at critical stages of crop development. However, there is little research on cultivar responses to this scenario and technologies that enhance water use efficiency (WUE). To determine the influence of water stress at and after flowering stages of drip-irrigated upland rice cultivars on physiology, yield, and WUE, a shelter experiment was conducted using a randomized block design with a split-plot arrangement of treatments. Three modern and one traditional cultivar were subjected to five irrigation managements: 100% of the field capacity considered the reference management (RM), 70 and 40% of the RM at the flowering stage, and 70 and 40% of the RM at the grain-filling stage. In general, the modern cultivars tended to maintain higher photosynthetic rate, stomatal conductance, transpiration, leaf water potential, and lower crop water stress index compared to the traditional cultivar under water stress. The WUE decreased for all cultivars under severe stress, averaging 0.55 and 0.62 kg m−3 when stress occurred at flowering and grain-filling, respectively, whereas moderate stress imposed at grain-filling maintained WUE for all cultivars, averaging 1.21 kg m−3. In addition, grain yield (GY) showed a similar variation trend under drought stress as WUE, and its reduction was mainly associated with low filled grain percentage. Among the five irrigation treatments, both GY and WUE were the highest in the RM; the best cultivar recorded 9.3 Mg ha−1 and 1.62 kg m−3, respectively. Findings suggest that attending to the full water demand under precision drip irrigation and appropriate cultivar selection can enhance upland rice production at significant levels.