To study the effects of late sowing and density on the lodging resistance and yield of rapeseed, and to provide the theoretical and technical support for the mechanized production of rapeseed, using three canola varieties (Shaanyou 28, Qinyou 28, and Qinyou 7) as the experimental materials, three sowing dates (T1: September 24, T2: October 1, and T3: October 8), and three densities (D1: 225,000 plants hm-2, D2: 450,000 plants hm-2, and D3: 675,000 plants hm-2) were set up to analyze the yield and constituent factors, the indexes related to lodging, the main components of the stem and the microstructure of the stem. The results showed that: (1) Under T1 and T2 treatments, with the increase of plant density, the yield of each plant of the three varieties decreased, the group yield increased first and then decreased, the lodging index decreased first and then increased, the vascular bundle and stem cross-sectional area decreased, the vascular bundle area/stem cross-sectional area, stem lignin, and cellulose content increased first and then decreased, the group yield was the largest at D2, while the lodging index was the smallest, and the yield and lodging resistance increased synergistically. Under the late sowing condition (T3), with the increase of density, the yield, lodging index, stem lignin, and cellulose content, above-ground fresh weight, vascular bundle area, stem cross-sectional area, and their ratios of the three cultivars decreased significantly, the group yield and lodging resistance increased, the lignin content was significantly positively correlated with the lodging resistance of stems, and the population yield and material resistance reached the maximum at D3. Compared with the normal sowing period (T1), the effective pods per plant, seeds per pod, yield per plant, population yield, and above-ground fresh weight the lodging index of each plant decreased significantly under the late sowing condition (T3), but the lodging resistance was enhanced. (2) Under the normal sowing period (T1), when the yield of the three variety groups was the highest, planting density was 450,000 plants hm-2. When the sowing date was delayed from T1 to T3, the yield of the three varieties was the highest at the density of 675,000 plants hm-2, among which Shaanyou 28 had the best density tolerance and late sowing resistance. In conclusion, under the late sowing condition, selecting dense and late sowing tolerant varieties and moderately increasing the density can compensate for the lack of yield, significantly increase the lignin and cellulose content of the stem, enhance the lodging resistance of rapeseed, effectively coordinate the contradiction between high yield and lodging, and achieve high yield and lodging resistance of late sowing rapeseed by compensating late with dense.
WeChat
WeChat