Impact of Irrigation on Winter Wheat Yield and Water Consumption: A Comparative Study

4.1 Yield and Water Consumption: Implications for Water Management

This study investigated the impact of different irrigation treatments on winter wheat yield and water consumption. Our results indicate that minimum irrigation yields were significantly lower than conventional irrigation yields, consistent with previous findings (Gao et al., 2022; Wang et al., 2018; Zhang et al., 2020; Xu et al., 2018). We observed that the yield differences between irrigation treatments were strongly correlated with ear number and kernel number per ear (Wang et al., 2018). This aligns with previous research suggesting that irrigation focused on bottom moisture water influences the development of ear number and kernel number per ear (Wang et al., 2018).

Pre-flowering water stress negatively impacts ear number, limiting tiller development during the nutritional growth phase and accelerating stem senescence while reducing spike number (Foulkes et al., 2011; M.Z. Siddiqui and Choudhary, 2017). Day and Intalap (1970) reported that stress during the nodulation stage was also crucial for spring wheat planted in December in Arizona, a region with sandy soils and high evaporative demand.

A sufficient water supply during winter wheat's flowering period is crucial for reproductive growth and yield formation (Sun et al., 2006). Kernel number per ear was influenced by water stress before and after flowering and during the stem elongation period (B et al., 2000). Under drought stress conditions, flag leaf material accumulation remained stable, but material accumulation in the spike and the two internodes below the spike was reduced, leading to florets degeneration (Zhang et al., 2020). Irrigation applied at jointing and anthesis could enhance grain yield by increasing ear number and kernel number per ear (Xu et al., 2018).

Our study found no significant difference in thousand-kernel weight between the three treatments, a result that deviates from previous findings (Wang et al., 2018). Wang et al. (2018) observed a higher thousand-kernel weight with minimum irrigation compared to the control. However, the filling period of winter wheat in our study region typically experiences dry heat winds, which cause rapid senescence and death of winter wheat, resulting in lower filling rates (Wang et al., 2018). The flowering period of winter wheat under reduced irrigation conditions usually occurs a few days earlier compared to conventional irrigation, which helps to avoid dry hot winds during the filling period. The lack of a significant increase in thousand-kernel weight in our study might be attributed to varietal differences.

Our study revealed that Opt and Min practices consumed less water compared to Con practices, resulting in improved water use efficiency (Fig. 2). This observation aligns with the findings reported by Zhang et al. (1998). The total water consumption in our study consisted primarily of rainfall, irrigation, and soil water depletion. The Min practice involved less irrigation and more soil water depletion than the Con practice, indicating more efficient rainfall utilization compared to the Con practice (Wang et al., 2018).

In conclusion, our study suggests that water management practices, such as minimum irrigation, can enhance water use efficiency while maintaining yield levels. Our findings also highlight the importance of adequate water supply during winter wheat's flowering period and the effects of pre-flowering water stress on tiller development and spike number. Further research is needed to investigate the impact of varietal differences on thousand-kernel weight and the effect of reduced irrigation on other crop species.