Effects of Water Application Frequency and Water Use Efficiency Under Deficit Irrigation on Maize Yield in Xinjiang

Revised text (relevant sections in red)

Table 3. Maize sowing, sampling, and harvest timelines across four growing stages (2018–2021)

Original text

Revised version (relevant sections in red)

4.1. High-Frequency Limited Irrigation Improves Water Use Efficiency

This study demonstrated that high-frequency limited irrigation (HL) significantly enhanced water use efficiency (WUE) and maize yield compared to low-frequency conventional irrigation (LC). Although HL reduced yield by 28.7% compared to high-frequency conventional irrigation (HC), it achieved this with 50% less irrigation (2400 vs. 4800 m³·hm⁻2), improving WUE by 18.6% over LC (from 3.06 to 3.63 kg·m⁻³; p < 0.05; Table 6). These findings align with recent studies in arid regions, where optimizing irrigation frequency is critical for balancing water conservation and crop productivity [34].

The superior WUE under HL arose from its ability to maintain stable soil moisture through frequent, small-volume irrigation. By delivering water in smaller doses, HL alleviated water stress during critical stages such as flowering and grain filling (Figure 4), which are highly sensitive to moisture deficits [35,36]. This stress mitigation sup-ported enhanced plant performance, as evidenced by 9.9% higher leaf area values in HL plots compared to LC (Figure 3b). These results corroborate earlier work by Smith et al. [37], who reported that consistent soil moisture levels enhance nutrient uptake and root biomass allocation in maize.

In contrast, LC induced cyclical soil moisture fluctuations, leading to a 15.4% re-duction in maize yield (p < 0.05). This decline underscores the sensitivity of maize to irregular water supply under arid conditions [38]. Such fluctuations disrupt stomatal conductance and limit carbon assimilation, ultimately impairing grain formation. Thus, HL irrigation offers a sustainable solution for arid regions like Xinjiang, where water scarcity threatens arable land [17]. Furthermore, by maintaining root-zone soil moisture stability [39], HL enables farmers to reduce water inputs by 50% while maximizing yield preservation—a critical advancement for water-saving agricultural practices.

4.2. Impact on Maize Physiology

Beyond WUE improvements, HL irrigation positively influenced maize physiology, particularly in photosynthesis and biomass partitioning. SPAD values (chlorophyll content) were 1.5% higher in HL-treated plants than in LC (p < 0.05; Figure 3), suggesting that frequent irrigation preserved leaf integrity under semi-arid conditions [40]. This aligns with global studies showing that stable water supply enhances chlorophyll synthesis, thereby enhancing photosynthetic efficiency [41,42]. For instance, the field experiment by Sayed et al. concluded that irrigation frequency directly correlates with chlorophyll fluorescence parameters in water-limited environments [43].

The physiological benefits of HL extended to dry matter allocation. At maturity, HL plants exhibited a 10.7% higher harvest index than LC (p < 0.05; Table 5), indicating efficient translocation of assimilates from stems and leaves to grains [44,45]. This contrasts with LC, where irregular irrigation delayed grain filling and increased vegetative biomass by 9.4% (p < 0.05). Notably, HL’s impact on biomass partitioning mirrors trends observed in drip-irrigated wheat systems [46,47]. However, the findings are limited to a single cultivar and region, requiring further validation across diverse conditions.

This study reveals the resource optimization effect of high-frequency limited irrigation (HL, irrigation water volume 2400 m³·hm⁻²) in maize production in arid areas. Compared with low-frequency conventional irrigation (LC, irrigation water volume 2400 m³·hm⁻²), the HL treatment achieved multiple benefits while reducing irrigation water volume by 50%:1) The water use efficiency (WUE) was increased by 18.6% com-pared with LC (p > 0.05), showing an efficiency optimization trend, which is consistent with the threshold irrigation theory proposed by Du et al. [34]; 2) The harvest index in-creased by 10.7%, indicating that limited water was preferentially allocated to the grains. This characteristic of "reducing irrigation water volume by half while im-proving efficiency" provides a new path for balancing water-saving goals and yield stability in arid areas.

4.1. Physiological Mechanisms of Water Regulation Efficiency

HL's effectiveness originated from precision water management during reproductive phases (35-75 days post-sowing). By applying frequent, small-volume irrigation events (60 mm per event), HL maintained soil saturation within the 60%-80% range in the 0-40 cm layer. This approach effectively mitigated drought-induced suppression of carbon assimilation. Specifically, a 9.9% expansion in leaf area value (Figure 3b) and a 1.5% increase in SPAD values (Figure 3c) were observed. While statistically non-significant, the coordinated improvements in leaf area (+9.9%) and SPAD (+1.5%) aligned with reported delayed leaf senescence under a stable water supply [35]. Given that 90-95% of maize grain dry matter originates from reproductive-stage photosynthates [36], it is hypothesized that HL enhanced assimilate translocation to grains by stabilizing the functionality of photosynthetic organs. This hypothesis is supported by phenotypic evidence: a 3.8% increase in ear diameter under HL (Table 4) suggests enhanced sink capacity through an expanded grain spatial arrangement, mirroring the source-sink coordination mechanism identified in drought-resistant hybrids [15].

4.2. Climate-Adaptive Optimization

The successful implementation of HL was facilitated through climate-adaptive optimization. Specifically, 65% of seasonal precipitation is concentrated during the low water-demand seedling stage (Figure 1). This allowed HL to reduce early-stage irrigation by 15%, prioritizing water conservation during the moisture-sensitive reproductive phase. This contrasts with the "stage-specific water allocation" strategy, which increased WUE by 22% through concentrated jointing-stage irrigation in the North China Plain [19]. Under Xinjiang's extreme heat (28°C monthly average during repro-duction), HL's high-frequency irrigation counteracted rapid root-zone water depletion caused by high temperatures, thereby extending the applicability of Tan et al.'s [37] irrigation quota-efficiency quadratic relationship theory.

4.2. Unresolved Issues and Implementation Challenges

Although HL achieved a 12% increase in irrigation water use efficiency (IWUE) (Table 6), indicating improved shallow water utilization, the underlying root system responses still need to be verified. While Wu et al. [38] documented water fluctuation-induced increases in shallow root length density, this contrasts with Zhang et al.'s [39] recommendation of a 60 cm optimal root depth in gray desert soils. In situ, root imaging should be employed to elucidate the interactions between vertical water distribution and root architecture. Practically, HL erects a sustainable irrigation frame-work for groundwater-scarce regions like Xinjiang but confronts implementation hurdles. Smallholder farmers typically lack access to high-frequency irrigation technologies (e.g., drip systems) and the associated energy supplies. Policy interventions, including infrastructure subsidies and cultivar-specific adaptation trials, are pivotal to catalyzing HL adoption. Future research should prioritize: 1) Root phenomics to illuminate water uptake mechanisms;2) Multi-climate zone trials to authenticate strategy robustness;3) Development of dynamic irrigation models integrating frequency, volume, and climatic variables.

Revised text (relevant sections in red)

Water conservation is critical for global maize production, particularly in arid regions where water scarcity, exacerbated by climate change, threatens conventional irrigation sustainability. Optimizing irrigation strategies to reconcile water productivity and yield remains a key scientific challenge in water-limited agriculture. This four-year study (2018–2021) evaluated integrated irrigation management that combines frequency and volume adjustments. A field experiment evaluated three strategies: high-frequency deficit irrigation (HL: 2400 m³·hm⁻²), low-frequency conventional irrigation (LC: 2400 m³·hm⁻²), and high-frequency conventional irrigation (HC: 4800 m³·hm⁻²). Compared to LC, HL increased grain yield by 18.2% (10,793.78 vs. 9,129.11 kg·hm⁻²; p < 0.05) and water use efficiency (WUE) by 18.6% (3.63 vs. 3.06 kg·hm⁻³), while reducing water input by 50% versus HC. Physiological analysis revealed that HL alleviated drought stress through frequent small-volume applications, enhancing plant height (+2.6%), leaf area (+9.9%), and SPAD values (+1.5%). These improvements contrast with traditional water-saving methods that often sacrifice yield. The HL strategy demonstrates that synchronizing irrigation timing with crop water demand can overcome the yield-efficiency trade-off, providing a scalable framework for ar-id-land maize systems. Our findings propose a paradigm shift from volume-centric to frequency-optimized irrigation, offering actionable solutions for sustainable agriculture in water-scarce regions worldwide.

Revised text (relevant sections in red)

Water is a fundamental resource in agricultural production, directly influencing crop growth and development [1]. However, the global disparity in water distribution, exacerbated by escalating scarcity, poses critical threats to agricultural sustainability [2]. Xinjiang, a typical arid and semi-arid region in Northwest China, faces acute water shortages [3,4]. Water scarcity combined with inefficient irrigation practices has led to insufficient water supply for cultivated lands, increasing risks of agricultural abandonment [5]. Water scarcity, inefficient irrigation practices, and the risk of farmland abandonment in Xinjiang not only undermine regional agricultural productivity but also jeopardize China's food security [6]. Globally, agricultural land in arid and semi-arid regions is under water stress [7], underscoring the imperative to optimize irrigation strategies for sustainable agriculture.

To address these challenges, drip irrigation technology has emerged as a pivotal solution for water resource management in arid agricultural systems. As a globally adopted water-saving method, drip irrigation has demonstrated effectiveness in arid regions worldwide [8,9], including well-documented implementations in Xinjiang [10]. This system delivers water precisely to crop root zones, minimizing evaporation and leaching losses, thereby improving water use efficiency (WUE) [11-13]. Nevertheless, Xinjiang's extreme water scarcity strains crop water requirements, necessitating innovative irrigation strategies.  Given the critical role of water management under scar-city, selecting maize—a crop sensitive to water stress—provides an ideal model for determining optimal irrigation techniques [14].

Maize (Zea mays L.), a globally vital cereal crop with pronounced water sensitivity [15], is an ideal model for studying water management in arid agriculture. In China, maize occupies the largest cultivated area and achieves the highest grain yield [16], while in Xinjiang, it constitutes a cornerstone of local agriculture. Maize's water demand exhibits marked temporal heterogeneity: 40% of total water requirement occurs during the jointing stage, with 35% consumed during grain filling [17], as evidenced by studies in arid regions (e.g., the U.S. Midwest [18], North China Plain [19], and Sub-Saharan Africa [20]). Water deficit directly impairs maize physiology, manifesting as reduced stomatal conductance and photosynthetic rates under stress conditions [21], thereby depressing yields. Although plastic film-mulched drip irrigation is widely adopted in Xinjiang, farmers' reliance on suboptimal irrigation schedules compromises system efficiency and long-term sustainability [22]. Under water-limited conditions, irrigation frequency becomes a critical determinant of both WUE and crop performance [23]. High-frequency irrigation maintains stable soil moisture levels, facilitating root water uptake [24], whereas low-frequency irrigation induces moisture fluctuations detrimental to crop health [25]. The conventional irrigation quota of 4,800 m³·hm⁻² yr⁻¹ fails to meet crop water demands, resulting in partial field abandonment. Thus, deficit irrigation emerges as a viable strategy to reduce water consumption while maintaining acceptable productivity levels.

This study hypothesizes that high-frequency limited irrigation (HL) maintains root-zone soil moisture stability, thereby improving water use efficiency (WUE) with-out compromising yield, compared to low-frequency conventional irrigation (LC). To test this hypothesis, three irrigation strategies were evaluated: high-frequency conventional (HC), high-frequency limited (HL), and low-frequency conventional (LC). The objectives were to (1) quantify the effects of irrigation frequency and volume on maize growth and yield and (2) identify the optimal strategy for balancing water savings and agricultural productivity. The findings aim to provide a scalable framework for drip irrigation optimization in global arid regions.

Revised text (relevant sections in red)

The research took place between 2018 and 2021 at an experimental station in Shihezi, Xinjiang, China (86°09′E, 45°38′N), located in the western suburbs of Shihezi City in northwestern China. The site, which is at an altitude of 452.8 m above sea level, the site features a semi-arid climate characterized by an average yearly temperature of 22.46 °C and annual evaporation reaching 1,942 mm (Figure 1). The groundwater table fluctuates seasonally between 2 and 3 m below the surface. The experimental site contains grey desert soil (USDA Soil Taxonomy) with the following physicochemical properties measured at 0-20 cm depth using stainless-steel auger sampling: organic matter 16.79 g·kg⁻¹, total nitrogen was measured at 1.44 g·kg⁻¹, while available phosphorus stood at 26.52 mg·kg⁻¹, and available potassium at 415.98 mg·kg⁻¹. The pH level was recorded as 8.19, with a bulk density of 1.56 g·cm⁻³, saturated water content 32.01%, and Soil saturation 60 - 80%. Additionally, key physicochemical parameters of the irrigation water are detailed in Table 1.

Table 1. Physicochemical properties of irrigation water.

The experiment utilized plastic film-mulched drip irrigation with water treat-ments designed based on local water availability, comprising three treatments: (i) high-frequency conventional irrigation (HC, 4800 m³·hm^⁻2, 100% quota), (ii) high-frequency limited irrigation (HL, 2400 m³·hm^⁻2, 50% quota), and (iii) low-frequency conventional irrigation (LC, 2400 m³·hm^-2, 50% quota). We arranged treatments in a randomized complete block design with three replications, resulting in nine experimental plots (20 m × 5.5 m each). Adjacent plots were separated by 2.2 m buffer zones to minimize edge effects (Figure 2a). A combined seeder performed three synchronized operations: (1) laying drip tapes (inner diameter: 16 mm; wall thickness: 0.18 mm; emitter spacing: 300 mm; Xinjiang Water Saving Co.), (2) applying plastic film mulch, and (3) sowing maize seeds. The irrigation system operated at 0.1-0.15 MPa, with each emitter delivering 2.0 L·h⁻¹. Drip tapes were spaced 110 cm apart, and each plot had independent water meters and fertilizer tanks for precise irrigation and fertigation control. Maize was planted in alternating wide-narrow rows (80 cm wide, 30 cm narrow), achieving a target density of 1.26 × 10⁵ plants hm-2 through 14.4 cm within-row spacing (Figure 2b).

All plant experiments and field studies adhered to relevant institutional regulations, as well as national (Ministry of Agriculture and Rural Affairs of the People's Republic of China) and international guidelines for field research (CIMMYT).

Chlorophyll content（SPAD Measurement）: (The measurement of SPAD values, which serve as an indicator of leaf chlorophyll content, was conducted using a SPAD-502 meter from Konica Minolta, Japan.) at flowering and maturity stages. For each plot, 10 representative fully expanded leaves were selected.

2.5. Statistical Analysis

Date from all experiments were assessed using Microsoft Excel 2010 and SPSS Statistics 27.0. The assumption of normality and the homogeneity of variances were tested using the Shapiro-Wilk and Levene's tests, respectively. Treatment comparisons were conducted using one-way ANOVA, followed by LSD post hoc tests with a significance level set at p < 0.05. Nonparametric Kruskal-Wallis H (multiple groups) or Mann-Whitney U (two groups) tests were used for non-normal data, while Welch's test addressed unequal variances. Graphical representations of the results were generated using Origin 2021 software.

Revised text (relevant sections in red)

3.1. Effects of Irrigation Frequency and Amount on Maize Growth Parameters

The impact of irrigation frequency and amount on maize growth parameters demonstrated numerical variations. Although the differences in plant height, leaf area, and SPAD values (chlorophyll content) between the two low-water (Total irrigation water volume) treatments were not statistically significant, high-frequency limited irrigation (HL) showed numerically higher growth metrics with no statistical significance to low-frequency conventional irrigation (LC). Specifically, HL was associated with a 2.6% numerically greater plant height (244.09 ± 14.34 vs. 237.84 ± 19.08 cm), a 9.9% numerically larger leaf area (371.32 ± 32.42 vs. 337.73 ± 22.11 cm²), and a 1.5% numerically higher SPAD value (49.40 ± 0.56 vs. 48.65 ± 0.40). However, these differences were not statistically significant (Figure 3a-c). At flowering and maturity, plant height values under HL and LC shared no statistical difference despite numerical variation (Figure 3a), indicating comparable growth despite numerical differences.

Figure 3:

Note: Different lowercase letters indicate significant differences between treatments for each index within the same growth period. All comparisons were considered significant at p < 0.05, LSD test unless noted. The leaf area at the flowering stage: Welch test (p > 0.05).

Figure 4:

Note: Distinct lowercase letters indicate significant differences (LSD test, p < 0.05) in the dry matter of each maize part within the same growth period across various treatments.

3.5. Key Growth Parameters Driving Maize Yield

The experimental data demonstrated that maize yield correlated strongly with total biomass, ear diameter, and thousand-kernel weight (Figure 5), with statistical significance denoted by asterisks (no significant p>0.05, * 0.01≤p≤0.05, **p≤0.01 and ***p≤0.001). Specifically, yield showed a significant positive correlation with ear diameter (R² = 0.66, p = 0.019) and total biomass dry matter (R²= 0.73, p = 0.008), and demonstrated a highly significant positive correlation with thousand-kernel weight (R²= 0.86, p < 0.001). Thousand-kernel weight exhibited the strongest predictive power (86% explained variance), followed by total biomass (73%) and ear diameter (66%). These quantitative correlations highlight that thousand-kernel weight is the dominant driver of yield variation, while ear diameter and total biomass provide complementary explanatory value.

Original text

Revised version

4.1. High-Frequency Limited Irrigation Improves Water Use Efficiency

This study demonstrated that high-frequency limited irrigation (HL) significantly enhanced water use efficiency (WUE) and maize yield compared to low-frequency conventional irrigation (LC). Although HL reduced yield by 28.7% compared to high-frequency conventional irrigation (HC), it achieved this with 50% less irrigation (2400 vs. 4800 m³·hm⁻2), improving WUE by 18.6% over LC (from 3.06 to 3.63 kg·m⁻³; p < 0.05; Table 6). These findings align with recent studies in arid regions, where optimizing irrigation frequency is critical for balancing water conservation and crop productivity [34].

The superior WUE under HL arose from its ability to maintain stable soil moisture through frequent, small-volume irrigation. By delivering water in smaller doses, HL alleviated water stress during critical stages such as flowering and grain filling (Figure 4), which are highly sensitive to moisture deficits [35,36]. This stress mitigation sup-ported enhanced plant performance, as evidenced by 9.9% higher leaf area values in HL plots compared to LC (Figure 3b). These results corroborate earlier work by Smith et al. [37], who reported that consistent soil moisture levels enhance nutrient uptake and root biomass allocation in maize.

In contrast, LC induced cyclical soil moisture fluctuations, leading to a 15.4% re-duction in maize yield (p < 0.05). This decline underscores the sensitivity of maize to irregular water supply under arid conditions [38]. Such fluctuations disrupt stomatal conductance and limit carbon assimilation, ultimately impairing grain formation. Thus, HL irrigation offers a sustainable solution for arid regions like Xinjiang, where water scarcity threatens arable land [17]. Furthermore, by maintaining root-zone soil moisture stability [39], HL enables farmers to reduce water inputs by 50% while maximizing yield preservation—a critical advancement for water-saving agricultural practices.

4.2. Impact on Maize Physiology

Beyond WUE improvements, HL irrigation positively influenced maize physiology, particularly in photosynthesis and biomass partitioning. SPAD values (chlorophyll content) were 1.5% higher in HL-treated plants than in LC (p < 0.05; Figure 3), suggesting that frequent irrigation preserved leaf integrity under semi-arid conditions [40]. This aligns with global studies showing that stable water supply enhances chlorophyll synthesis, thereby enhancing photosynthetic efficiency [41,42]. For instance, the field experiment by Sayed et al. concluded that irrigation frequency directly correlates with chlorophyll fluorescence parameters in water-limited environments [43].

The physiological benefits of HL extended to dry matter allocation. At maturity, HL plants exhibited a 10.7% higher harvest index than LC (p < 0.05; Table 5), indicating efficient translocation of assimilates from stems and leaves to grains [44,45]. This contrasts with LC, where irregular irrigation delayed grain filling and increased vegetative biomass by 9.4% (p < 0.05). Notably, HL’s impact on biomass partitioning mirrors trends observed in drip-irrigated wheat systems [46,47]. However, the findings are limited to a single cultivar and region, requiring further validation across diverse conditions.

This study reveals the resource optimization effect of high-frequency limited irrigation (HL, irrigation water volume 2400 m³·hm⁻²) in maize production in arid areas.       Compared with low-frequency conventional irrigation (LC, irrigation water volume 2400 m³·hm⁻²), the HL treatment achieved multiple benefits while reducing irrigation water volume by 50%:1) The water use efficiency (WUE) was increased by 18.6% com-pared with LC (p > 0.05), showing an efficiency optimization trend, which is consistent with the threshold irrigation theory proposed by Du et al. [34]; 2) The harvest index in-creased by 10.7%, indicating that limited water was preferentially allocated to the grains. This characteristic of "reducing irrigation water volume by half while im-proving efficiency" provides a new path for balancing water-saving goals and yield stability in arid areas.

4.1. Physiological Mechanisms of Water Regulation Efficiency

HL's effectiveness originated from precision water management during reproductive phases (35-75 days post-sowing). By applying frequent, small-volume irrigation events (60 mm per event), HL maintained soil saturation within the 60%-80% range in the 0-40 cm layer. This approach effectively mitigated drought-induced suppression of carbon assimilation. Specifically, a 9.9% expansion in leaf area value (Figure 3b) and a 1.5% increase in SPAD values (Figure 3c) were observed. While statistically non-significant, the coordinated improvements in leaf area (+9.9%) and SPAD (+1.5%) aligned with reported delayed leaf senescence under a stable water supply [35]. Given that 90-95% of maize grain dry matter originates from reproductive-stage photosynthates [36], it is hypothesized that HL enhanced assimilate translocation to grains by stabilizing the functionality of photosynthetic organs. This hypothesis is supported by phenotypic evidence: a 3.8% increase in ear diameter under HL (Table 4) suggests enhanced sink capacity through an expanded grain spatial arrangement, mirroring the source-sink coordination mechanism identified in drought-resistant hybrids [15].

4.2. Climate-Adaptive Optimization

The successful implementation of HL was facilitated through climate-adaptive optimization. Specifically, 65% of seasonal precipitation is concentrated during the low water-demand seedling stage (Figure 1). This allowed HL to reduce early-stage irrigation by 15%, prioritizing water conservation during the moisture-sensitive reproductive phase. This contrasts with the "stage-specific water allocation" strategy, which increased WUE by 22% through concentrated jointing-stage irrigation in the North China Plain [19]. Under Xinjiang's extreme heat (28°C monthly average during reproduction), HL's high-frequency irrigation counteracted rapid root-zone water depletion caused by high temperatures, thereby extending the applicability of Tan et al.'s [37] irrigation quota-efficiency quadratic relationship theory.

4.2. Unresolved Issues and Implementation Challenges

Although HL achieved a 12% increase in irrigation water use efficiency (IWUE) (Table 6), indicating improved shallow water utilization, the underlying root system responses still need to be verified. While Wu et al. [38] documented water fluctuation-induced increases in shallow root length density, this contrasts with Zhang et al.'s [39] recommendation of a 60 cm optimal root depth in gray desert soils. In situ, root imaging should be employed to elucidate the interactions between vertical water distribution and root architecture. Practically, HL erects a sustainable irrigation frame-work for groundwater-scarce regions like Xinjiang but confronts implementation hurdles. Smallholder farmers typically lack access to high-frequency irrigation technologies (e.g., drip systems) and the associated energy supplies. Policy interventions, including infrastructure subsidies and cultivar-specific adaptation trials, are pivotal to catalyzing HL adoption. Future research should prioritize: 1) Root phenomics to illuminate water uptake mechanisms;2) Multi-climate zone trials to authenticate strategy robustness;3) Development of dynamic irrigation models integrating frequency, volume, and climatic variables.

Revised text (relevant sections in red)

This study demonstrated that high-frequency limited irrigation (HL) effectively enhances water use efficiency (WUE) while maintaining maize yield under water-limited conditions. Although both HL and low-frequency conventional irrigation (LC) reduced vegetative growth compared to high-frequency conventional irrigation (HC), HL outperformed LC in grain production and water productivity under identical irrigation quotas. This strategy mitigated risks of water scarcity-induced land abandonment and yield reduction. These results validate that the HL, through targeted irrigation scheduling, enhances agricultural water productivity in Xinjiang and provides a scalable adaptive framework for arid agroecosystems.

Revised text (relevant sections in red)

3.1. Effects of Irrigation Frequency and Amount on Maize Growth Parameters

The impact of irrigation frequency and amount on maize growth parameters demonstrated numerical variations. Although the differences in plant height, leaf area, and SPAD values (chlorophyll content) between the two low-water (Total irrigation water volume) treatments were not statistically significant, high-frequency limited irrigation (HL) showed numerically higher growth metrics with no statistical significance to low-frequency conventional irrigation (LC). Specifically, HL was associated with a 2.6% numerically greater plant height (244.09 ± 14.34 vs. 237.84 ± 19.08 cm), a 9.9% numerically larger leaf area (371.32 ± 32.42 vs. 337.73 ± 22.11 cm²), and a 1.5% numerically higher SPAD value (49.40 ± 0.56 vs. 48.65 ± 0.40). However, these differences were not statistically significant (Figure 3a-c). At flowering and maturity, plant height values under HL and LC shared no statistical difference despite numerical variation (Figure 3a), indicating comparable growth despite numerical differences.

Revised text (relevant sections in red)

Dry matter accumulation in maize during flowering and maturity stages varied across irrigation treatments between irrigation treatments. Aboveground biomass accumulation was higher under high-frequency limited irrigation (HL) compared to low-frequency conventional irrigation (LC). At maturity, total biomass under HL reached 22,310.58 ± 884.10 kg·hm⁻², representing a 6.83% increase compared to LC (20,884.84 ± 645.47 kg·hm⁻²). Dry matter accumulation in all plant organs: leaf biomass under HL was significantly higher (+14.7%), while stem (+2.7%) and reproductive organ (+9.8%) accumulations showed non-significant gains (Figure 4a-b). HL treatment increased the translocation efficiency of dry matter from vegetative organs to grains by 12.2% compared to LC, resulting in a 18.6% higher grain yield (Table 5).

Revised text (relevant sections in red)

Deficit irrigation and irrigation frequency influenced maize yield and its components (Table 4). Yield data showed that high-frequency limited irrigation (HL) was numerically higher than low-frequency conventional irrigation (LC) by 18.2% (10,793.78 ± 1013.98 kg·hm⁻² vs. 9,129.11 ± 1313.38 kg·hm⁻²). In terms of yield components, HL treatment exhibited better numerical values across several parameters. The numerical values of ear length, number of kernels per row, and thousand-kernel weight were all higher under HL than under LC, contributing to the increased yield. But these differences were not statistically significant as indicated by the same letter annotations in the table.

Revised text (relevant sections in red)

The effects of irrigation volume and frequency on maize biomass translocation and related indices showed numerical variations (p < 0.05, LSD test for significant parameters). As irrigation volume and frequency decreased, dry matter translocation and associated metrics tended to decline. Specifically, the HL treatment exhibited a numerically 23.0% higher dry matter translocation than LC, though not statistically significant (Table 5). In terms of dry matter translocation efficiency, HL showed a 12.2% numerical increase compared to LC, though not statistically significant (Table 5). Furthermore, the harvest index in the HL treatment declined less than in LC: HL had a 16.6% reduction, versus 24.7% for LC, resulting in an 8.1% smaller decline in HL, though not statistically significant (Table 5).

Revised text (relevant sections in red)

Irrigation water use efficiency (IWUE) was significantly higher in high-frequency limited irrigation (HL) compared to low-frequency conventional irrigation (LC) (Table 6). The WUE for HL reached 3.63 kg·m⁻³, representing an 18.6% numerical increase compared to LC (3.06 kg·m⁻³; p > 0.05, Kruskal-WAllis H test). The irrigation water use efficiency (IWUE), is calculated as yield per unit irrigation water applied. The HL treatment exhibited an 18.4% enhancement in IWUE relative to LC (p < 0.05, LSD test). Regarding precipitation use efficiency (PUE), the HL treatment showed a 21.8% numerical improvement over LC in PUE values (20.99 ± 8.74 kg·m⁻³ vs. 17.24 ± 5.95 kg·m⁻³, p > 0.05, Welch test).

Original text

Revised version

4.1. High-Frequency Limited Irrigation Improves Water Use Efficiency

This study demonstrated that high-frequency limited irrigation (HL) significantly enhanced water use efficiency (WUE) and maize yield compared to low-frequency conventional irrigation (LC). Although HL reduced yield by 28.7% compared to high-frequency conventional irrigation (HC), it achieved this with 50% less irrigation (2400 vs. 4800 m³·hm⁻2), improving WUE by 18.6% over LC (from 3.06 to 3.63 kg·m⁻³; p < 0.05; Table 6). These findings align with recent studies in arid regions, where optimizing irrigation frequency is critical for balancing water conservation and crop productivity [34].

The superior WUE under HL arose from its ability to maintain stable soil moisture through frequent, small-volume irrigation. By delivering water in smaller doses, HL alleviated water stress during critical stages such as flowering and grain filling (Figure 4), which are highly sensitive to moisture deficits [35,36]. This stress mitigation sup-ported enhanced plant performance, as evidenced by 9.9% higher leaf area values in HL plots compared to LC (Figure 3b). These results corroborate earlier work by Smith et al. [37], who reported that consistent soil moisture levels enhance nutrient uptake and root biomass allocation in maize.

In contrast, LC induced cyclical soil moisture fluctuations, leading to a 15.4% re-duction in maize yield (p < 0.05). This decline underscores the sensitivity of maize to irregular water supply under arid conditions [38]. Such fluctuations disrupt stomatal conductance and limit carbon assimilation, ultimately impairing grain formation. Thus, HL irrigation offers a sustainable solution for arid regions like Xinjiang, where water scarcity threatens arable land [17]. Furthermore, by maintaining root-zone soil moisture stability [39], HL enables farmers to reduce water inputs by 50% while maximizing yield preservation—a critical advancement for water-saving agricultural practices.

4.2. Impact on Maize Physiology

Beyond WUE improvements, HL irrigation positively influenced maize physiology, particularly in photosynthesis and biomass partitioning. SPAD values (chlorophyll content) were 1.5% higher in HL-treated plants than in LC (p < 0.05; Figure 3), suggesting that frequent irrigation preserved leaf integrity under semi-arid conditions [40]. This aligns with global studies showing that stable water supply enhances chlorophyll synthesis, thereby enhancing photosynthetic efficiency [41,42]. For instance, the field experiment by Sayed et al. concluded that irrigation frequency directly correlates with chlorophyll fluorescence parameters in water-limited environments [43].

The physiological benefits of HL extended to dry matter allocation. At maturity, HL plants exhibited a 10.7% higher harvest index than LC (p < 0.05; Table 5), indicating efficient translocation of assimilates from stems and leaves to grains [44,45]. This contrasts with LC, where irregular irrigation delayed grain filling and increased vegetative biomass by 9.4% (p < 0.05). Notably, HL’s impact on biomass partitioning mirrors trends observed in drip-irrigated wheat systems [46,47]. However, the findings are limited to a single cultivar and region, requiring further validation across diverse conditions.

This study reveals the resource optimization effect of high-frequency limited irrigation (HL, irrigation water volume 2400 m³·hm⁻²) in maize production in arid areas. Compared with low-frequency conventional irrigation (LC, irrigation water volume 2400 m³·hm⁻²), the HL treatment achieved multiple benefits while reducing irrigation water volume by 50%:1) The water use efficiency (WUE) was increased by 18.6% com-pared with LC (p > 0.05), showing an efficiency optimization trend, which is consistent with the threshold irrigation theory proposed by Du et al. [34]; 2) The harvest index in-creased by 10.7%, indicating that limited water was preferentially allocated to the grains. This characteristic of "reducing irrigation water volume by half while im-proving efficiency" provides a new path for balancing water-saving goals and yield stability in arid areas.

4.1. Physiological Mechanisms of Water Regulation Efficiency

HL's effectiveness originated from precision water management during reproductive phases (35-75 days post-sowing). By applying frequent, small-volume irrigation events (60 mm per event), HL maintained soil saturation within the 60%-80% range in the 0-40 cm layer. This approach effectively mitigated drought-induced suppression of carbon assimilation. Specifically, a 9.9% expansion in leaf area value (Figure 3b) and a 1.5% increase in SPAD values (Figure 3c) were observed. While statistically non-significant, the coordinated improvements in leaf area (+9.9%) and SPAD (+1.5%) aligned with reported delayed leaf senescence under a stable water supply [35]. Given that 90-95% of maize grain dry matter originates from reproductive-stage photosynthates [36], it is hypothesized that HL enhanced assimilate translocation to grains by stabilizing the functionality of photosynthetic organs. This hypothesis is supported by phenotypic evidence: a 3.8% increase in ear diameter under HL (Table 4) suggests enhanced sink capacity through an expanded grain spatial arrangement, mirroring the source-sink coordination mechanism identified in drought-resistant hybrids [15].

4.2. Climate-Adaptive Optimization

The successful implementation of HL was facilitated through climate-adaptive optimization. Specifically, 65% of seasonal precipitation is concentrated during the low water-demand seedling stage (Figure 1). This allowed HL to reduce early-stage irrigation by 15%, prioritizing water conservation during the moisture-sensitive reproductive phase. This contrasts with the "stage-specific water allocation" strategy, which increased WUE by 22% through concentrated jointing-stage irrigation in the North China Plain [19]. Under Xinjiang's extreme heat (28°C monthly average during repro-duction), HL's high-frequency irrigation counteracted rapid root-zone water depletion caused by high temperatures, thereby extending the applicability of Tan et al.'s [37] irrigation quota-efficiency quadratic relationship theory.

4.2. Unresolved Issues and Implementation Challenges

Although HL achieved a 12% increase in irrigation water use efficiency (IWUE) (Table 6), indicating improved shallow water utilization, the underlying root system responses still need to be verified. While Wu et al. [38] documented water fluctuation-induced increases in shallow root length density, this contrasts with Zhang et al.'s [39] recommendation of a 60 cm optimal root depth in gray desert soils. In situ, root imaging should be employed to elucidate the interactions between vertical water distribution and root architecture. Practically, HL erects a sustainable irrigation frame-work for groundwater-scarce regions like Xinjiang but confronts implementation hurdles. Smallholder farmers typically lack access to high-frequency irrigation technologies (e.g., drip systems) and the associated energy supplies. Policy interventions, including infrastructure subsidies and cultivar-specific adaptation trials, are pivotal to catalyzing HL adoption. Future research should prioritize: 1) Root phenomics to illuminate water uptake mechanisms;2) Multi-climate zone trials to authenticate strategy robustness;3) Development of dynamic irrigation models integrating frequency, volume, and climatic variables.

Revised text (relevant sections in red)

Dry Matter biomass: Aboveground biomass (leaves, stems, and reproductive organs) was harvested at flowering and maturity stages. The samples were dried in an oven at 105°C for 30 minutes and then at 75°C until they reached a constant weight.

Dry matter translocation (kg·hm⁻²) was calculated as the difference in stem and leaf dry matter between flowering and maturity stages:

Dry matter transfer efficiency (%) was determined by dividing the translocation value by the stem and leaf dry matter at flowering stage, then multiplying by 100:

2.4.2. Maize Yields and Yield Components

At maize maturity, 20 randomly selected plants each plot were harvested.  Ears were manually threshed, and grains were dried to 14% moisture content. Total kernel weight and 1000-kernel weight were recorded. Grain yield per hectare was converted based on plot area.

The yield (kg·hm⁻²) is calculated using the formula:

The harvest index (%) is derived as follows:

For the contribution of dry matter translocation to grain (%), it is calculated by:

Original text

Revised version

Water conservation is critical for global maize production, particularly in arid regions where water scarcity, exacerbated by climate change, threatens conventional irrigation sustainability. Optimizing irrigation strategies to reconcile water productivity and yield remains a key scientific challenge in water-limited agriculture. This four-year study (2018–2021) evaluated integrated irrigation management that combines frequency and volume adjustments. A field experiment evaluated three strategies: high-frequency deficit irrigation (HL: 2400 m³·hm⁻²), low-frequency conventional irrigation (LC: 2400 m³·hm⁻²), and high-frequency conventional irrigation (HC: 4800 m³·hm⁻²). Compared to LC, HL increased grain yield by 18.2% (10,793.78 vs. 9,129.11 kg·hm⁻²; p < 0.05) and water use efficiency (WUE) by 18.6% (3.63 vs. 3.06 kg·hm⁻³), while reducing water input by 50% versus HC. Physiological analysis revealed that HL alleviated drought stress through frequent small-volume applications, enhancing plant height (+2.6%), leaf area (+9.9%), and SPAD values (+1.5%). These improvements contrast with traditional water-saving methods that often sacrifice yield. The HL strategy demonstrates that synchronizing irrigation timing with crop water demand can overcome the yield-efficiency trade-off, providing a scalable framework for arid-land maize systems. Our findings propose a paradigm shift from volume-centric to frequency-optimized irrigation, offering actionable solutions for sustainable agriculture in water-scarce regions worldwide.

Water conservation is critical for global maize production, particularly in arid regions where water scarcity, exacerbated by climate change, threatens conventional irrigation sustainability. Optimizing irrigation strategies to reconcile water productivity and yield remains a key scientific challenge in water-limited agriculture. This four-year study (2018–2021) evaluated integrated irrigation management that combines frequency and volume adjustments. A field experiment compared three strategies: high-frequency limited irrigation (HL: 2400 m³·hm⁻²), low-frequency conventional irrigation (LC: 2400 m³·hm⁻²), and high-frequency conventional irrigation (HC: 4800 m³·hm⁻²). Interannual analyses demonstrated that HL significantly outperformed LC in grain yield and water use efficiency (WUE) during drought years, increasing both parameters by 36% (2020) and 23.9% (2021; p < 0.05). Four-year average comparisons revealed no significant differences in yield (10,793.78 vs. 9,129.11 kg·hm⁻²) or WUE (3.63 vs. 3.06 kg·m⁻³; p > 0.05). Physiological evaluations indicated that HL mitigated drought stress via frequent small-volume irrigation, with numerically marginal increases in plant height (+2.6%), leaf area (+9.9%), and SPAD values (+1.5%), although these changes remained statistically insignificant (p > 0.05). Collectively, HL partially mitigated drought stress during critical water-demand stages, yet its inconsistent multi-year performance limited broad applicability. The strategy exhibits context-dependent potential for synchronizing irrigation with crop water requirements, particularly in regions with predictable dry seasons, while universal implementation necessitates further validation. These findings underscore the need for climate-adaptive irrigation optimization over uniform solutions in water-scarce agricultural systems.

Original text

Revised version

This study demonstrated that high-frequency limited irrigation (HL) effectively enhances water use efficiency (WUE) while maintaining maize yield under water-limited conditions. Although both HL and low-frequency conventional irrigation (LC) reduced vegetative growth compared to high-frequency conventional irrigation (HC), HL outperformed LC in grain production and water productivity under identical irrigation quotas. This strategy mitigated risks of water scarcity-induced land abandonment and yield reduction. These results validate that the HL, through targeted irrigation scheduling, enhances agricultural water productivity in Xinjiang and provides a scalable adaptive framework for arid agroecosystems.

This study demonstrated that during the drought years of 2020–2021, high-frequency limited irrigation (HL) significantly enhanced maize grain yield (by 36% in 2020 and 23.9% in 2021) and water use efficiency (WUE) compared with low-frequency conventional irrigation (LC) under equivalent irrigation quotas (p < 0.05).However, four-year average yields (10,793.78 vs. 9,129.11 kg·hm⁻²) and WUE (3.63 vs. 3.06 kg·m⁻³) exhibited no significant differences between HL and LC (p > 0.05). By synchronizing irrigation with critical crop water demand periods, HL mitigated drought stress, indicating its potential applicability in agroecosystems with predictable dry seasons. The findings underscore the context-dependent benefits of this strategy: while effective in specific drought scenarios, its inconsistent multi-year performance necessitates climate-adaptive irrigation optimization over universal adoption.

Revised text (relevant sections in red)

Irrigation water use efficiency (IWUE) was significantly higher in high-frequency limited irrigation (HL) compared to low-frequency conventional irrigation (LC) (Table 6). The WUE for HL reached 3.63 kg·m⁻³, representing an 18.6% numerical increase compared to LC (3.06 kg·m⁻³; p > 0.05, Kruskal-WAllis H test). The irrigation water use efficiency (IWUE), is calculated as yield per unit irrigation water applied. The HL treatment exhibited an 18.4% enhancement in IWUE relative to LC (p < 0.05, LSD test). Regarding precipitation use efficiency (PUE), the HL treatment showed a 21.8% numerical improvement over LC in PUE values (20.99 ± 8.74 kg·m⁻³ vs. 17.24 ± 5.95 kg·m⁻³, p > 0.05, Welch test). Year and irrigation treatment significantly influenced yield, water use efficiency (WUE), irrigation water use efficiency (IWUE), and precipitation use efficiency (PUE), with a significant interaction observed between the two factors.

Table 6. Effect on water use efficiency of maize under different irrigation treatment

Note: Different lowercase letters denote significant differences (p < 0.05) between treatments for each indicator. Due to - the homogeneity of variances, Welch's test was applied to WUE, IWUE, and PUE in 2020, as well as to the average PUE; the average WUE, failing the normality test, was analyzed using a non - parametric method. The LSD method was used for the remaining data. Here, *** denotes p<0.001.

Original text

Revised version

Water conservation is critical for global maize production, particularly in arid regions where water scarcity, exacerbated by climate change, threatens conventional irrigation sustainability. Optimizing irrigation strategies to reconcile water productivity and yield remains a key scientific challenge in water-limited agriculture. This four-year study (2018–2021) evaluated integrated irrigation management that combines frequency and volume adjustments. A field experiment compared three strategies: high-frequency limited irrigation (HL: 2400 m³·hm⁻²), low-frequency conventional irrigation (LC: 2400 m³·hm⁻²), and high-frequency conventional irrigation (HC: 4800 m³·hm⁻²). Interannual analyses demonstrated that HL significantly outperformed LC in grain yield and water use efficiency (WUE) during drought years, increasing both parameters by 36% (2020) and 23.9% (2021; p < 0.05). Four-year average comparisons revealed no significant differences in yield (10,793.78 vs. 9,129.11 kg·hm⁻²) or WUE (3.63 vs. 3.06 kg·m⁻³; p > 0.05). Physiological evaluations indicated that HL mitigated drought stress via frequent small-volume irrigation, with numerically marginal increases in plant height (+2.6%), leaf area (+9.9%), and SPAD values (+1.5%), although these changes remained statistically insignificant (p > 0.05). Collectively, HL partially mitigated drought stress during critical water-demand stages, yet its inconsistent multi-year performance limited broad applicability. The strategy exhibits context-dependent potential for synchronizing irrigation with crop water requirements, particularly in regions with predictable dry seasons, while universal implementation necessitates further validation. These findings underscore the need for climate-adaptive irrigation optimization over uniform solutions in water-scarce agricultural systems.

Water conservation is critical for global maize production, particularly in arid regions where water scarcity, exacerbated by climate change, threatens conventional irrigation sustainability. Optimizing irrigation strategies to reconcile water productivity and yield remains a key scientific challenge in water-limited agriculture. This four-year study (2018–2021) evaluated integrated irrigation management that combines frequency and volume adjustments. A field experiment compared three strategies: high-frequency limited irrigation (HL: 2400 m³·hm⁻²), low-frequency conventional irrigation (LC: 2400 m³·hm⁻²), and high-frequency conventional irrigation (HC: 4800 m³·hm⁻²). four-year mean yield showed HL (10,793.78 kg·hm⁻²) had a non-significant 18.2% numerical advantage over LC (9,129.11 kg·hm⁻², p >0.05). The WUE for HL reached 3.63 kg·m⁻³, representing an 18.6% numerical increase com-pared to LC (3.06 kg·m⁻³; p > 0.05). Physiological parameters (plant height +2.6%, leaf area +9.9%, SPAD +1.5%) showed marginal improvements in HL, yet lacked both statistical significance (p >0.05) and strong yield correlation. Multi-year analyses confirmed no statistically distinguishable differences between strategies (p >0.05), demonstrating irrigation frequency adjustments alone cannot reliably enhance drought resilience. These findings caution against advocating HL as a superior practice, given the statistical equivalence between HL and LC despite water savings, and the non-significant yield gap between HL and HC. Future research must establish causality through models integrating re-al-time soil-crop-climate feedbacks prior to recommending altered irrigation regimes.

Original text

Revised version

This study demonstrated that during the drought years of 2020–2021, high-frequency limited irrigation (HL) significantly enhanced maize grain yield (by 36% in 2020 and 23.9% in 2021) and water use efficiency (WUE) compared with low-frequency conventional irrigation (LC) under equivalent irrigation quotas (p < 0.05).However, four-year average yields (10,793.78 vs. 9,129.11 kg·hm⁻²) and WUE (3.63 vs. 3.06 kg·m⁻³) exhibited no significant differences between HL and LC (p > 0.05). By synchronizing irrigation with critical crop water demand periods, HL mitigated drought stress, indicating its potential applicability in agroecosystems with predictable dry seasons. The findings underscore the context-dependent benefits of this strategy: while effective in specific drought scenarios, its inconsistent multi-year performance necessitates climate-adaptive irrigation optimization over universal adoption.

This study shows that high - frequency limited irrigation (HL) numerically im-proves water use efficiency (WUE) and has a yield advantage over low - frequency conventional irrigation (LC) under the same irrigation volume. Though physiological parameters in HL improved marginally, there were no statistically significant differences between strategies. HL can help save water and maintain maize yield in water - limited conditions, offering a potential adaptive approach for arid regions. However, future research with models integrating real - time feedback is needed before recommending HL.