Maize-peanut intercropping system can enhance resource utilization efficiency and yield. However, the yield of peanuts in the edge and middle rows decreases after the flower-pegging stage due to the shading effect of maize. Foliar spraying of potassium dihydrogen phosphate can effectively alleviate this impact. This study aimed to elucidate the regulatory effects of foliar potassium dihydrogen phosphate application on membrane system damage, defense capacity, and yield in intercropped peanut systems, for providing a theoretical basis for high-yield cultivation management of maize-peanut intercropping system.

Using the maize variety Liangyu 99 and the peanut variety Huayu 22 as experimental materials, a maize:peanut with 2:4 intercropping system was employed. During the flower-pegging stage, foliar applications of a 0.5% potassium dihydrogen phosphate solution were administered three times at a rate of 730 kg·hm^-2 per application, to investigate the effects of foliar potassium dihydrogen phosphate application on peanut membrane system damage, osmoregulatory capacity, antioxidant enzyme activity, and yield.

In maize-peanut intercropping system, foliar application of potassium dihydrogen phosphate significantly reduced both the relative electrical conductivity and malondialdehyde content in peanuts compared with no treatment. During the pod-filling stage, relative electrical conductivity values in sole cropping plots, middle rows of intercropping plots, and edge rows of intercropping plots decreased by 15.56%, 35.29%, and 43.37%, respectively, compared with untreated controls, respectively. The trend in malondialdehyde levels mirrored that of relative electrical conductivity: sole cropping < intercropping middle rows < intercropping edge rows. Foliar application also markedly increased soluble protein, soluble sugar, and free proline content in peanuts while enhancing antioxidant enzyme activity, with edge rows demonstrating significantly superior effects to middle rows, which in turn outperformed sole cropping. Consequently, foliar application substantially improved individual peanut plants' fruit number, full fruit weight per plant, and total weight per hundred fruits compared with control conditions, with yield increases 7.24%-18.86% in sole cropping, 14.48%-20.02% in middle rows, and 16.75%-33.13% in edge rows. There were significantly greater yield improvements in intercropping system than in sole cropping.

During the flower-pegging stage, foliar applications of a 0.5% potassium dihydrogen phosphate solution could help mitigate leaf membrane system damage caused by peanut shading in maize, enhance its osmoregulatory capacity and antioxidant enzyme activity, increase both the number and weight of full fruits per plant as well as the total weight per hundred fruits, thereby improving peanut yield under the maize–peanut intercropping system.