加气对西北旱区膜下滴灌棉花生长与水分利用效率的影响

针对膜下滴灌棉田土壤根际低氧胁迫抑制棉花水分利用问题,探讨不同生长阶段加气灌溉对棉花生长发育及水分利用的影响。研究设置了苗期、蕾期、花铃期、蕾期+花铃期、苗期+蕾期+花铃期5个加气阶段,以生育期不加气为对照进行田间试验。结果表明：花铃期加气土壤呼吸和土壤温度峰值较其他处理延后了9 d,使加气效果得到延长,更好地改善了土壤环境,在获得最大产量的同时,水分利用效率也最高。土壤氧气含量对棉花产量的影响程度最大,且花铃期土壤氧气含量对产量和水分利用效率的正面影响均大于其他生育期。因此,在棉花花铃期进行加气灌溉是缓解覆膜造成的棉花根际低氧胁迫,提升棉花产量与水分利用效率的最佳时期。研究结果对揭示加气灌溉对棉花生长的影响机制及进一步提高水土资源利用率提供了理论依据。

Effects of aeration on the growth and water use efficiency of cotton under mulched drip irrigation in the dry areas of Northwest China

Abstract: Low-oxygen stress can pose a considerable threat to cotton production in the Xinjiang dry regions of Northwest China. Aerated irrigation has been widely considered to optimize the soil water-aeration environment, thus mitigating the adverse effects of low oxygen stress on the crop. However, aerated irrigation can also increase the irrigation time for less irrigation efficiency. Therefore, it is very necessary to consider the sensitivity of the cotton to hypoxic stress at different growth stages. A reasonable mode of aerated irrigation can also be established to quantify the response of the cotton growth and yield to the hypoxic stress during cultivation. Moreover, there is no consensus on the sensitivity of the cotton to low oxygen stress at various growth stages at present. This study aims to determine the effects of aerated irrigation at different growth stages on the soil environment, cotton growth, yield, and water production. A correlation was also made between the soil oxygen concentration, soil respiration rate, and soil temperature, with the cotton growth and yield. A field experiment was then conducted at the Key Laboratory of Modern Water-saving Irrigation of Xinjiang Production and Construction Corps at Shihezi University in Xinjiang, China, in 2021. The experimental settings were aerated irrigation (the dissolved oxygen concentration of 15 mg/L), and conventional non-aerated treatment (CK, the dissolved oxygen concentration of 5 mg/L) at the seedling (AS), budding (AB), flowering and boll (AF), budding + flowering and boll (ABF), and seedling + budding + flowering and boll (AW) stage. There were a total of 18 plots with three times repeated. The cotton variety was selected as "Xin Lu early 42", which was sown on April 15 and harvested on September 30. The subsurface drip irrigation was adopted for aerating using Mazzei air injector (Mazzei air injector 1078, American). A measurement was conducted on the soil oxygen content, soil respiration rate, soil temperature, plant height, stem diameter, leaf area index, yield, yield components, and water use efficiency. The results showed that the aerated irrigation at different stages effectively improved the soil environment in the root zone, plant growth, and development. There was a significant increase in the cotton yield from 2.33% to 15.82%. The soil oxygen content, soil respiration, and temperature significantly increased by 36.5% to 42.3%, 26.2% to 78.3%, and 13.7% to 26.9%, respectively, under aerated irrigation. A sudden decrease was observed in the soil oxygen content at the seedling and budding stages at the end of aerating. By contrast, the soil oxygen content continued to increase during the rest of the growth stages. The peak of soil respiration rate and soil temperature at the flowering and boll stage was delayed by 9 days, compared with the other treatments. The aerating was prolonged to better improve the soil environment. The stem diameter significantly increased by 36.5% by aerating at the seedling stage. The stem height, stem diameter, and leaf area index at the budding stage also significantly increased by 18.5%, 6.17%, and 31.9% after aerating. The stem diameter and leaf area index were significantly increased by 6.7% and 19.2% at the flowering and boll stages. The stem height, stem diameter, and leaf area index significantly increased by 19.9%, 6.83%, and 32.3% at the budding + flowering and boll stage. The plant height, stem diameter, and leaf area index of the aerated treatment at the seedling + budding + flowering and boll stage significantly increased by 27.7%, 7.05%, and 32.9%, respectively. The greatest effect was achieved in the aerated irrigation on the yield and yield components at different growth stages for the three fertility stages of aerated treatment at seedling, budding and flowering, and boll stage, followed by the aerated treatment at the flowering and boll stage, two fertility stages of aerated treatment at budding and flowering and boll stage, aerated treatment at the seedling stage, and finally the aerated treatment at the budding stage. Water use efficiency of AS, AF, and AW treatments significantly increased by 4.46%, 10.52%, and 7.60%, respectively, compared with the CK treatment. There was no significant difference between the AB, ABF, and CK treatments. Consequently, the aerating in the early stage of cotton growth was beneficial to the strong seedlings, while the middle stage was easy to cause the cotton branches and leaves to grow, and the most suitable period for aerating to improve yield was the late stage. As such, aerated irrigation was recommended at the flowering and boll stage in terms of energy loss, nutrient distribution, and cotton yield. The finding can provide a theoretical basis to reveal the effect of aerated irrigation on cotton growth, thus improving the utilization of soil and water resources.