Achieving optimal balance between maize yield and water use efficiency is an important challenge for irrigation maize production in arid areas. In this study, we conducted an experiment in Xinjiang China in 2016 and 2017 to quantify the response of maize yield and water use to plant density and irrigation schedules. The treatments included four irrigation levels: 360 (W1), 480 (W2), 600 (W3), and 720 mm (W4), and five plant densities: 7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m⁻² (D5). The results showed that increasing the plant density and the irrigation level could both significantly increase the leaf area index (LAI). However, LAI expansion significantly increased evapotranspiration (ET_a) under irrigation. The combination of irrigation level 600 mm (W3) and plant density 12.0 plants m⁻² (D4) produced the highest maize yield (21.0–21.2 t ha⁻¹), ET_a (784.1–797.8 mm), and water use efficiency (WUE) (2.64–2.70 kg m⁻³), with an LAI of 8.5–8.7 at the silking stage. The relationship between LAI and grain yield and evapotranspiration were quantified, and, based on this, the relationship between water use and maize productivity was analyzed. Moreover, the optimal LAI was established to determine the reasonable irrigation level and coordinate the relationship between the increase in grain yield and the decrease in water use efficiency.

We investigated the effects of variety, planting density, and irrigation amount on grain yield, water-use efficiency (WUE), and evapotranspiration (ETc). The trial was conducted in Tong Liao, Inner Mongolia, from 2021 to 2022, with compact variety Dika159 (DK159) and conventional variety Zhengdan958 (ZD958) as the test materials. The planting density was set to 6.0 × 10⁴ plants/ha (D1, local farmer planting density) and 9.0 × 10⁴ plants/ha (D2), with five irrigation levels: 450 mm (W₄₅₀, irrigation amount used by local farmers, CK); 360 mm (W₃₆₀); 270 mm (W₂₇₀); 180 mm (W₁₈₀); and 90 mm (W₉₀). The results indicate that the yield and WUE of variety DK159 increased by 7.48% and 5.00%, compared to ZD958, respectively. Increasing planting density enhanced yield by 13.32–15.57% in maize yield and 9.55–11.47% in WUE. Maize yield exhibited a trend of increasing linearly with the irrigation amount before reaching a plateau, reaching a maximum (16.62–17.39 t/ha) and high WUE (2.45–2.49 kg/m³) with DK159-D2-W₂₇₀. The highest water consumption intensity occurred during the silking stage to the milk stage for different densities and varieties. The results indicate that selecting compact varieties, increasing planting density, and optimizing irrigation amount through integrated drip irrigation and water fertilizer can effectively improve maize yield and WUE.

High grain yield and water use efficiency (WUE) are the key goals when producing maize (Zea mays L.) under irrigation in arid areas. Increasing the planting density and optimizing irrigation are important agronomic practices for increasing the maize grain yield and WUE. A two-year field experiment was conducted to investigate the effects of planting density and irrigation on the maize grain yield, WUE, and economic return of spring maize under a mulch drip irrigation system in Xinjiang, Northwest China. The experiment included four irrigation levels and five planting densities. The results showed that the reduction of irrigation decreased the yield and evapotranspiration (ET_c) but improved the WUE. Increasing the planting density increased the ET_c, but there was a quadratic curve relationship between yield and WUE and planting density. Treatment with 600 mm of water and 12 plants m⁻² obtained the highest grain yield (21.0–21.2 t ha⁻¹) and economic return (3036.0 USD ha⁻¹) and a relatively high WUE (2.64–2.70 kg kg⁻¹). Therefore, a reasonable increase in planting density and an appropriate reduction of irrigation combined with drip irrigation under a mulch system can simultaneously achieve high yields and economic return and high WUE in maize production.

High yield is one of the important goals of crop production, and close planting and optimum irrigation systems are important agronomic practices for increasing maize (Zea mays L.) grain yield. However, little is known about the effect of optimal irrigation interval on the photosynthetic rate (P_n) and dry matter accumulation (DM) of closely planted super-high-yield maize under drip irrigation under mulch. Therefore, the objective of this study was to determine the effects of irrigation interval on the leaf P_n, DM, and grain yield of closely planted super-high-yield maize under mulch drip irrigation in the Xinjiang Uygur Autonomous Region, Northwestern China. A field experiment was conducted using three irrigation intervals in 2016—namely, six days (D6), nine days (D9), and 12 days (D12)—and five irrigation intervals in 2017—namely, three days (D3), six days (D6), nine days (D9), 12 days (D12), and 15 days (D15). The Xianyu 335 high-yield maize hybrid was used in the test; the planting density was set to 12×10⁴ plants ha⁻¹, and an optimal irrigation quota of 540 mm was used. The results showed that during the irrigation period, (1) the soil moisture content (SMC), DM, leaf P_n, and grain yield of treatment D6 were higher than for other irrigation intervals, (2) the leaf P_n and stomatal conductance (G_S) of the leaves of treatments D3, D9, D12, and D15 were significantly correlated with the SMC of the 0–40 cm soil layer, and (3) the leaf P_n of treatment D6 was significantly positively correlated with SMC in the 0–60 cm soil layer but not significantly correlated with G_S. Irrigation treatment D6 was found to maintain high SMC, provide a water environment favorable to the growth of maize, and increase the leaf P_n and DM, and thereby obtain maize grain yield (20.6–21.0 t ha⁻¹). Therefore, an optimal irrigation interval could be beneficial for adjusting soil moisture, leaf P_n, and DM in order to increase maize grain yield with drip irrigation under mulch.

Water conservation and grain yield improvement are primary objectives for sustainable agricultural development in arid and semi-arid regions. Variety selection, planting density, and irrigation management represent crucial agronomic practices that regulate root–crown growth and grain yield in maize. A two-year field experiment was carried out from 2021 to 2022 in Tongliao, Inner Mongolia Autonomous Region, China. Two widely cultivated maize varieties, DK159 and ZD958, were used as test materials. Two planting densities were designed: 60,000 plants ha⁻¹ (D1, local farmers’ conventional density) and 90,000 plants ha⁻¹ (D2). Five irrigation levels were established: 450 mm (I5, local farmers’ practice, CK), 360 mm (I4), 270 mm (I3), 180 mm (I2), and 90 mm (I1). We investigated the interactive effects of variety, planting density, and irrigation amount on dry matter accumulation pre- and post-silking, root spatial distribution characteristics, and the coordination mechanism of root–shoot growth in maize under shallow-buried drip irrigation. The results indicated that grain yield under DK159 was 5.37–6.69% higher than that under ZD958, and the yield under D2 was 13.32–15.89% higher than that under D1. At the D1 density, no significant difference in grain yield was observed between I2 and I5, with yields ranging from 12.90 to 13.92 t ha⁻¹. At the D2 density, grain yield under I3 was statistically similar to that under I5, ranging from 15.54 to 17.39 t ha⁻¹. Compared with local farmers’ conventional planting density and full irrigation regime, increasing planting density and reducing irrigation amount altered the vertical root distribution of maize. The proportion of roots distributed in the 0–20 cm topsoil layer decreased, while appropriate water deficit markedly increased root proportion in the 40–60 cm subsoil layer. Increasing planting density and moderately reducing irrigation effectively promoted pre- and post-silking dry matter accumulation while maintaining a high harvest index (HI). At silking stage, the root–shoot ratio increased initially and then stabilized with increasing irrigation amount. At maturity, the root–shoot ratio gradually decreased and tended to be stable as irrigation increased. Therefore, the adoption of water-efficient maize varieties, combined with appropriately increased planting density and optimized irrigation regimes, can coordinate root–shoot relationships in the early growth period, facilitate early root establishment and late-stage nutrient accumulation, and thus improve maize yield. Under the conditions of shallow-buried drip irrigation in the supplementary irrigation area of the West Liaohe Plain, the adoption of water-saving maize varieties, appropriately increased planting density, and optimized irrigation regimes can coordinate the developmental relationship between root and above-ground growth, promote early root development and late-stage nutrient accumulation, and thereby simultaneously increase maize grain yield. These results provide practical theoretical and technical references for achieving high-yield and water-saving maize production under similar ecological conditions.