Abstract: 【Objective】To analyze the effects of different planting densities and row spacing configurations on stem carbohydrate accumulation and lodging resistance of wheat under ridge-furrow rainfall harvesting planting mode, to clarify the reasonable density and row spacing of wheat under ridge-furrow rainfall harvesting planting mode, these results provided a theoretical basis for further stabilizing and increasing wheat yield.【Method】Xinong 979 which is the main wheat cultivar in the arid area of north was used as the experimental material, in 2019-2021, two densities (low density: 1.8 million plants per hm²; high density: 2.25 million plants per hm²) and two row spacing (equal row spacing: 20 cm; non-equal spacing: 12.5 cm∶35 cm∶12.5 cm) treatments were set in the rainfall harvesting planting mode, we analyzed the effects of different densities and row spacing on photosynthetic rate of middle and lower leaves in wheat plants, contents of stem non-structural carbohydrates and structural carbohydrates, stem breaking moment and lodging index, and grain yield.【Result】The photosynthetic rate (Pn) of the middle and lower leaves (inverted three-leaf, inverted four-leaf, and inverted five-leaf) in wheat plants, the contents of non-structural carbohydrates (glucose, fructose, sucrose) and structural carbohydrates (hemicellulose, cellulose) in the second internode at the base of stem, and the stem breaking moment were significantly decreased with the increase of planting density in the rainfall harvesting planting mode, the stem lodging index increased significantly; however, under high-density planting condition, non-equal row spacing treatment could significantly change all plant indexes, among them, compared with high planting density + equal spacing treatment, the Pn of inverted three-leaf, inverted four-leaf and inverted five-leaf in plants increased significantly, with increases of 7.7%-16.5%, 5.3%-37.7% and 11.9%-24.9%, respectively, the contents of glucose, fructose and sucrose in stems increased by 9.8%-15.0%, 8.8%-27.4% and 8.2%-41.1%, the contents of hemicellulose and cellulose increased by 4.5%-19.8%, 5.9%-31.2%, and the stem breaking moment increased by 4.8%-17.3%, the stem lodging index decreased by 10.9%-25.9%, wheat yield was also significantly increased by 13.5%-15.2%. Correlation analysis showed that, the contents of glucose, fructose and sucrose in the basal internode of wheat stem were positively correlated with the contents of hemicellulose and cellulose. Non-structural carbohydrates and structural carbohydrates in wheat stem were positively correlated with Pn of middle and lower leaves and stem breaking moment, however, they were negatively correlated with lodging index.【Conclusion】Under the rainfall harvesting planting mode, adjusting population spatial distribution by non-equal row spacing could effectively increase photosynthetic rate of middle and lower leaves of wheat plants, promote the synthesis and accumulation of sugar substances in stems, enhance the lodging resistance of wheat stem, furthermore, reduce the lodging incidence of wheat and improve grain yield.

Key words: wheat, rainfall harvesting planting, planting density, row spacing configuration, lodging