Optimizing Winter Wheat Yield and Water Use Efficiency: The Role of Irrigation and Weather Conditions

4.1 Different Yield and Water Consumption Response for Diverse Water Management

This study examined the effects of various irrigation treatments on winter wheat yield. The minimum irrigation yield was significantly lower, aligning with previous research (Gao et al., 2022; Wang et al., 2018; Zhang et al., 2020; Xu et al., 2018). Yield variations between irrigation treatments were strongly correlated with ear number and kernel number per ear (Wang et al., 2018), confirming prior findings that only irrigation of bottom moisture water influences the development of ear and kernel numbers (Wang et al., 2018).

Pre-flowering water stress was found to impact ear number (Foulkes et al., 2011; M.Z. Siddiqui and Choudhary, 2017). Plant water stress restricts tiller development during nutritional growth, and stress at the pulling stage accelerates stem senescence, reducing spike number. Day and Intalap (1970) noted that in Arizona (sandy soils in a high evaporative demand climate), spring wheat planted in December, stress at the nodulation stage was also significant due to reduced seed numbers.

Winter wheat's flowering period is critical for reproductive growth and yield formation, requiring adequate water supply for yield improvement (Sun et al., 2006). The kernel number per ear was found to be impacted by water stress before and after flowering and during the stem elongation period (B et al., 2000). Drought stress significantly reduces both strong grains in the top spikelet and weak grains in the middle spikelet (Zhang et al., 2020). Under drought stress, flag leaf material accumulation remains stable, while material accumulation in the spike and two internodes below is reduced. This leads to less competition for assimilates by the spike compared to the two internodes below, and the competition for assimilates between the spike and stem under drought may have promoted florets degeneration. These results highlight that irrigation at jointing and anthesis could enhance grain yield by increasing ear numbers and kernel number per ear (Xu et al., 2018).

There was no significant difference in thousand-kernel weight between the three treatments, deviating from previous findings (Wang et al., 2018). Under Wang's practice (Wang et al., 2018), the thousand-kernel weight with minimum irrigation was 11.6%, 5.2%, and 11.0% higher than the control. Winter wheat's filling period in this region typically occurs from early May to early June. However, dry heat winds often occur during the filling period (early June), causing rapid senescence and death of winter wheat, leading to lower filling rates (Wang et al., 2018). However, the flowering period of winter wheat under reduced irrigation conditions is usually a few days earlier compared to conventional irrigation, which helps to avoid dry hot winds in the filling period. The lack of a significant increase in thousand-kernel weight might be attributed to varietal differences.

During the winter wheat season, Opt and Min practices consumed less water compared to Con practices, resulting in increased water use efficiency (Fig. 2), consistent with findings by Zhang et al. (1998). In this study, total water consumption primarily comprised rainfall, irrigation, and soil water depletion. Min practice had less irrigation and more soil water depletion compared to Con, indicating more efficient rainfall use (Wang et al., 2018).

4.2 Effect of Weather Conditions on Yield and Water Consumption

This study investigated the influence of weather conditions on winter wheat yield and water consumption. The results showed that Con and Opt practices were primarily affected by minimum temperature and dry hot winds during the filling stage, while Min practice was predominantly influenced by pre-flowering rainfall conditions impacting ear number. These findings align with previous studies emphasizing the significant role of weather conditions in determining crop yield and water use efficiency (Liu et al., 2017; Wang et al., 2018).

Low minimum temperatures during the filling stage negatively impact winter wheat yield by reducing filling rates and dry matter accumulation in grains (Wang et al., 2018). Dry hot winds during the filling stage also contribute to rapid senescence and death of winter wheat, leading to decreased filling rates (Wang et al., 2018). These findings suggest that irrigation management should be adjusted to account for weather conditions during the filling stage to optimize yield.

Pre-flowering rainfall conditions also play a significant role in determining winter wheat yield. The study found that ear number was significantly affected by pre-flowering water stress, which restricts tiller development during nutritional growth (Foulkes et al., 2011; M.Z. Siddiqui and Choudhary, 2017). These findings emphasize the need for proactive water management strategies that consider pre-flowering rainfall conditions to ensure optimal yield.

4.3 Implications for Water Management

This study offers significant implications for water management strategies aimed at optimizing winter wheat yield and water use efficiency. The findings demonstrate that minimum irrigation leads to yield reduction, primarily due to water stress from jointing to flowering. Conversely, irrigation at jointing and anthesis can improve grain yield by increasing ear numbers and kernel number per ear.

Furthermore, the study suggests that weather conditions should be incorporated when designing water management strategies. Low minimum temperatures and dry hot winds during the filling stage should be considered when determining irrigation schedules to ensure optimal yield. Similarly, pre-flowering rainfall conditions should be considered to avoid water stress that hinders tiller development during nutritional growth.

In conclusion, this study provides valuable insights into the intricate interplay between water management and weather conditions in influencing winter wheat yield and water use efficiency. These findings can inform the development of practical water management strategies that optimize yield while minimizing water consumption.