Effects of nitrogen strategies on population quality and grain yield of mechanical sowing wheat under intercropping condition in Sichuan Hilly Areas

A medium-gluten wheat cultivar, Chuanmai 42, was taken as an experiment material, the effects of nitrogen levels and application patterns on population quality and grain yield of strip-relay-intercropping wheat (half planted compared with sole-cropping wheat) were studied using the split block experiment design. The results show that leaf area index (LAI) of wheat after jointing, and the dry matter accumulation are increased with increase of nitrogen levels, while grain-leaf ratio is increased at first and then decreased, and the ratio reaches its largest value at the nitrogen rate of 180 kg/ha. Simultaneously, the LAI after flowering, the dry matter accumulation per day and grain-leaf ratio are all improved effectively at the dressing ratio of 7:3 (base fertilizer: jointing fertilizer). In aspect of yield, spike number and seeds per panicle are increased with increase of nitrogen levels, while the earbearing tiller percentage and 1000-grain weight are increased at first and then percentage is improved effectively at the dressing ratio of 7:3 (base fertilizer: jointing fertilizer). The results of correlation analysis show that the LAI after booting, the dry matter accumulation at booting and the dry matter accumulation per day are significantly correlated with grain yield. In the present study, the spike number, number of seeds per panicle and 1000-grain weight are optimal under the nitrogen amount of 180 kg/ha combined with dressing ratio of 7:3 (base fertilizer: jointing fertilizer), and the highest grain yield is 4800.4 kg/ha. The corresponding population indexes under this nitrogen strategy are 184.5104 /ha of the seedling number, 225.3104 /ha of the spike number, 72.8% of the spike rate, 4.68 of the highest LAI at booting, 2.11 of LAI at filling, 1600.6 kg/ha of post-anthesis dry matter accumulation, 9652.5104 /ha of seeds number and 11.501 mg/cm2 of grain-leaf ratio, respectively.