Effect of sowing date, planting density, and nitrogen application on dry matter accumulation, transfer, distribution, and yield of wheat

To clarify the regulation mechanism of sowing date, planting density, and nitrogen application on yield, a three-factor fracture zone-test design was adopted. The sowing dates were October 12 and November 12 (represented as ST and LT, respectively); the planting densities were 2.25×10⁶ plants·hm^-2, 3.00×10⁶ plants·hm^-2, and 3.75×10⁶ plants·hm^-2 (represented as M1, M2, and M3, respectively); and nitrogen fertilizers were applied at three rates to each planting density (pure N 150 kg·hm^-2, 225 kg·hm^-2, and 300 kg·hm^-2, represented as N1, N2, and N3, respectively). The effects of different sowing dates, planting densities, and nitrogen application rates on dry matter accumulation, transfer and yield of 'Annongda 1216' were studied. The interaction of sowing date, planting density, and nitrogen application rate significantly affected yield and its components, nitrogen use efficiency, dry matter accumulation, dry matter transfer before anthesis, dry matter accumulation after anthesis, and dry matter distribution at maturity. Under the ST condition, the dry matter accumulation amount at anthesis and maturity, dry matter accumulation amount after anthesis and its contribution to grain, spike number, kernel number per spike, 1000-grain weight, and yield were significantly higher than those under LT condition. Under the ST and LT conditions, the spike number, dry matter accumulation amount at anthesis and maturity under the M2 and M3 treatments were significantly higher than those under the M1 treatment. On the other hand, the grain number per spike, dry matter accumulation amount after anthesis and its contribution to grain, grain weight and its proportion under the M2 treatment were significantly higher than those under the M1 and M3 treatments. The spike number, dry matter accumulation amount at anthesis and maturity, dry matter accumulation amount after anthesis and its contribution to grain under the N3 treatment were significantly higher than those under the N1 and N2 treatments. The grain number per spike, 1000-grain weight, grain weight and its proportion at maturity stage in the M1 and M2 treatments under the ST condition and all planting density treatments under LT condition were significantly higher than those under the N1 and N2 treatments. Under the conditions of this experiment, applying nitrogen fertilizer and increasing planting densities appropriately were beneficial to increase grain yield. 'Annongda 1216' sown on October 12 at a density of 3.00×10⁶ plants·hm^-2 with a nitrogen application rate of 300 kg·hm^-2 showed a higher yield.