Diversified Water Management Impacts on Winter Wheat Yield and Water Use Efficiency

4.1 Effects of Diversified Water Management on Winter Wheat Yield and Water Consumption

The present study examined the effects of diverse water management strategies on winter wheat yield and water consumption. Our results demonstrate that different irrigation treatments significantly impact winter wheat yield. Specifically, minimum irrigation resulted in significantly lower yields compared to conventional irrigation, aligning with previous research (Gao et al., 2022; Wang et al., 2018; Zhang et al., 2020; Xu et al., 2018).

Yield variations among irrigation treatments were strongly correlated with ear number and kernel number per ear (Wang et al., 2018). Our findings support prior research indicating that irrigation focused on replenishing bottom moisture water directly influences ear number and kernel number per ear development (Wang et al., 2018). Pre-flowering water stress was identified as a key factor impacting ear number (Foulkes et al., 2011; M.Z. Siddiqui and Choudhary, 2017).

Water stress during the plant's nutritional growth phase limits tiller development, while stress during the pulling stage accelerates stem senescence and reduces spike number. Day and Intalap (1970) reported that in Arizona, with its sandy soils and high evaporative demand climate, spring wheat planted in December experiences significant stress at the nodulation stage due to reduced seed numbers.

Winter wheat's flowering period plays a crucial role in reproductive growth and yield formation, and adequate water supply is essential for maximizing yield (Sun et al., 2006). Our study found that kernel number per ear was influenced by water stress occurring before and after flowering, as well as during the stem elongation period (B et al., 2000). Drought stress significantly reduces both the strong grains of the top spikelet and the weak grains of the middle spikelet (Zhang et al., 2020). Under drought stress conditions, flag leaf material accumulation remained stable, while material accumulation in the spike and the two internodes below the spike decreased. This resulted in the spike competing less for assimilates compared to the two internodes below the spike, and competition for assimilates between the spike and stem under drought may have promoted floret degeneration.

Our findings demonstrate that irrigation applied at jointing and anthesis stages can improve grain yield by increasing ear numbers and kernel number per ear (Xu et al., 2018). However, we did not observe a difference in thousand-kernel weight between the three irrigation treatments, which contradicts the results of previous studies (Wang et al., 2018). It's important to note that under the Wang practice (Wang et al., 2018), the thousand-kernel weight with minimum irrigation was 11.6%, 5.2%, and 11.0% higher than the control, respectively.

The filling period of winter wheat in this region typically spans from early May to early June. Dry heat winds frequently occur during this period, particularly in early June, causing rapid senescence and death of winter wheat, leading to lower filling rates (Wang et al., 2018). However, winter wheat under reduced irrigation conditions tends to flower a few days earlier compared to conventional irrigation, which helps to avoid the impact of dry hot winds during the filling period. The lack of a significant increase in thousand-kernel weight in our study could be attributed to varietal differences.

During the winter wheat season, both Opt and Min practices consumed less water compared to Con practices, respectively, resulting in increased water use efficiency (Fig. 2), which aligns with the findings of Zhang et al. (1998). In our study, total water consumption was primarily composed of rainfall, irrigation, and soil water depletion. The Min practice utilized less irrigation and experienced greater soil water depletion compared to the Con practice, indicating more efficient rainfall utilization (Wang et al., 2018).

In conclusion, our study underscores the significance of diversified water management in enhancing winter wheat yield and water use efficiency. Our results suggest that irrigation applied at jointing and anthesis stages can improve grain yield by increasing ear numbers and kernel number per ear. Furthermore, our findings indicate that diversified water management practices, such as Opt and Min practices, can substantially reduce water consumption and improve water use efficiency. This research provides valuable insights for farmers and policymakers seeking to adopt sustainable water management practices in agricultural settings.