Abstract:

In order to clarify the effective ways for intercropping soybean to resist lodging, a field experiment of spraying plant growth regulators on soybean corn strip composite planting was conducted in the summer soybean growing season of 2023. A split zone design was adopted, with the main zone as the planting mode. Two planting modes were set up: soybean corn 6:4 mode (M₁) and soybean corn 6:3 mode (M₂); the sub zone was treated with growth regulators, consisting of four treatments: R₁ (silicon fertilizer), R₂ (silicon fertilizer+27.5% hexanoic·mepiquat chloride), R₃ (27.5% hexanoic·mepiquat chloride), and R₄ (water control); all together there were eight treatments. By systematically analyzing the differences in SPAD values, canopy nutritional indicators, lodging resistance traits, and yield indicators of soybean top three leaves among different treatments, the effects of silicon fertilizer and hexanoic·mepiquat chloride on the growth, development, and lodging resistance of intercropped soybeans were clarified. The results showed that during the grain filling stage of summer soybeans, the nutritional parameters of the plant canopy in each treatment were higher than those of the control. The R₂ treatment had the highest stem bending resistance, stem dry weight, and stem plumpness. The main stem length of the R₂ and R₃ treatments was lower than that of the R₁ and R₄ treatments, but the differences between treatments were not significant; the yield and yield components (number of pods per plant, number of grains per plant, and 100 grain weight) of each treatment were higher than those of the control R₄ treatment; the yield was highest in the R₂ treatment, and the yield of the M₁R₂ treatment was higher than that of the M₂R₂ treatment; the lodging resistance index was significantly positively correlated with stem bending resistance and stem thickness, and negatively correlated with main stem length. Both silicon fertilizer and hexanoic·mepiquat chloride spray can improve the nutritional indicators of the summer soybean canopy during the grain filling stage. At the same time, by increasing the stem bending resistance and stem plumpness of soybean plants, we can reduce plant height, improve soybean lodging resistance index, and inhibit plant lodging. In summary, silicon fertilizer and hexanoic·mepiquat chloride can promote plant photosynthetic production and yield formation by enhancing plant resistance, reducing plant height, and improving plant spatial structure.

Key words: summer soybean, plant growth regulators, silicon fertilizer, hexanoic·mepiquat chloride, growth and development, lodging resistance, soybeans and corn strip intercropping