限水灌溉下不同灌溉模式对夏玉米产量和水分利用效率的影响(英文)

Comparison of irrigation strategies for summer maize under deficit irrigation:Grain yield and water use efficiency

华北平原水资源短缺问题对传统农业灌溉方式提出挑战。限水灌溉条件下调整优化灌水模式是节约灌溉用水、提高水分利用效率(WUE)和作物产量的重要策略。基于此,本试验在2018—2019年两个生长季,在自动防雨棚内(消除自然降雨的影响)设置不同灌水模式,分析其对夏玉米产量和WUE的影响。本试验采用随机区组设计,设置2种灌水方式:畦灌(BI)和微喷灌(SI)。根据灌水总额和灌水频次分成2组对比模式。等量不等次组(SI-225和BI-225):灌水总额相同[50%耗水量(ET)],灌水频次不同, SI-225灌水频次为6次,分别在出苗(VE)、6展叶(V6)、10展叶(V10)、13展叶(V13)、吐丝期(VT)和灌浆期(R3);BI-225灌水频次为3次,分别在VE、V10和VT。等次不等量组(SI-225、SI-280、SI-352和BI-450):灌水频次相同(6次),灌水总额不同(分别为50%、60%、80%和100%ET),其中SI-225和BI-450为定额灌溉, SI-280和SI-352根据土壤墒情进行测墒补灌。结果表明,与BI-225相比, SI-225产量提高17.7%~20.2%, WUE提高9.2%~12.7%。进一步分析生理指标发现, SI-225通过小定额多次灌溉改善了上层土壤水分状况(0~40 cm),提高光合速率、叶面积指数和干物质积累,进而提高产量和WUE。在相同的灌水频次下,与BI-450相比, SI-225和SI-280产量降低21.2%和12.0%,但由于SI-225和SI-280降低了叶面积指数和呼吸速率,导致生育期总耗水量降低,进而提高WUE。与BI-450相比, SI-352的产量差异不显著(P>0.05),但SI-352通过优化叶面积指数和呼吸速率, ET降低9.8%,灌水量降低21.8%,进而WUE提高5.1%。因此,在限水灌溉条件下(50%of ET),通过提高灌水频次(小定额多次灌溉)可提高夏玉米的产量和WUE;在适度限水灌溉(80%of ET)下,采用微喷测墒补灌可实现稳产量、高水效。该研究结果可为华北平原缺水地区提高农业用水效率提供理论参考。

The shortage of water resources in the North China Plain(NCP) poses a challenge to traditional agricultural irrigation methods. Adjusting and optimizing the irrigation mode is an important strategy for saving water and improving water use efficiency(WUE) and crop yield under water-limited irrigation conditions. Given this background, different irrigation modes were set in an automatic rainproof shed(to eliminate the effects of natural rainfall) in the two growing seasons of 2018 and 2019 to analyze the grain yield and WUE of summer maize. In this experiment, a randomized block design was adopted, and two irrigation methods were applied: border irrigation(BI) and micro-sprinkler irrigation(SI). Based on the total irrigation amount and frequency, sample plots were divided into two groups for comparison. Plots in the first group(SI-225 and BI-225) had the same total irrigation amount(50% of evapotranspiration, ET) but different irrigation frequencies. SI-225 was irrigated six times, namely at the emergent seedling stage(VE), sixth leaf stage(V6), tenth leaf stage(V10), thirteenth leaf stage(V13), tasseling stage(VT), and milk stage(R3). BI-225 was irrigated three times at VE, V10, and VT. Plots in the second group(SI-225, SI-280, SI-352, and BI-450) had the same irrigation frequency but different total irrigation amounts(50%, 60%, 80%, and 100% of ET). Among them, SI-225 and BI-450 received a fixed amount of water per irrigation event, whereas SI-280 and SI-352 underwent supplementary irrigation according to their soil moisture content. The results showed that, compared with those of BI-225, the grain yield of SI-225 increased by 17.7%-20.2% and its WUE increased by 9.2%-12.7%. Further analysis of physiological characteristics revealed that SI-225 showed an improved upper soil water status(0-40 cm), increased photosynthetic rate(Pn), leaf area index(LAI), and dry matter accumulation, and consequently higher yield and WUE due to modest but highly frequent irrigation. Under the same irrigation frequency, the grain yields of SI-225 and SI-280 decreased by 21.2% and 12.0%, respectively, compared with that of BI-450. However, total water consumption during the growth period was reduced due to the decrease in LAI and transpiration rate(Tr) of SI-225 and SI-280, which resulted in an improved WUE.The grain yield of SI-352 did not differ significantly from that of BI-450, but its ET decreased by 9.8% due to the optimization of LAI and Tr, its irrigation amount decreased by 21.8%, and its WUE increased by 5.1%. Therefore, under water-limited irrigation conditions(50% of ET), the yield and WUE of summer maize could be increased by increasing the irrigation frequency, with modest but highly frequent irrigation promoting the best results. Moreover, under moderate water limitation(80% of ET), the application of micro-spraying supplementary irrigation based on soil moisture content allowed to achieve a stable yield and a high WUE. These results provide a theoretical reference for improving the efficiency of agricultural water use in water-deficient areas of the NCP.