Comparison of Water Utilization Patterns of Sunflowers and Maize at Different Fertility Stages along the Yellow River

Currently, there is a limited supply of freshwater on a worldwide scale, and finding effective ways to use agricultural freshwater resources has become a widely discussed subject. To investigate the most suitable crops and the efficient use of water resources in dry regions, we performed a comparison study of water consumption between two common crops, maize and sunflowers, in the irrigation area located on the south bank of the Yellow River in Northwest China. Both sunflowers and maize have diverse water sources at various reproductive phases. We discovered that sunflower predominantly consumes 0–50 cm soil water throughout the reproductive cycle, whereas maize mostly utilizes 0–50 cm soil water in the early reproductive phase and 50–90 cm soil water in the late reproductive period. The comparison of yield sustainability between sunflowers and maize demonstrated that sunflowers exhibited more resilience than maize when subjected to the same level of water decrease. Sunflowers’ yield sustainability score stayed consistently over 0.95, while maize had a lowest score of 0.84. We observed via correlation analysis that it was the fraction of subsurface water contribution and the water contribution of the 50~70 cm soil layer that impacted the yield of sunflowers and maize, with coefficients of 0.88 or higher. Ultimately, sunflowers exhibited a lower level of responsiveness to water scarcity compared to maize. Sunflowers have greater drought tolerance compared to maize since they rely less on soil layers replenished by a limited water supply. Based on our findings, sunflowers are well suited to arid conditions and limited spaces that do not have access to irrigation, while maize is better suited to well-watered conditions and expansive cultivation areas.