Abstract:

To study the effects of different sowing dates and sowing densities on population dynamics and lodging resistance of winter wheat under drip irrigation, Xindong 22 (less-spike type) and Handan 5316 (multi-spike type) were used as the test materials, the field test design of the split area was adopted, and the main area had three sowing dates: September 23 (B1), October 4 (B2) and October 15 (B3); the sub-area had four seeding densities: 3.15×10⁶·hm^-2 (M1), 5.10×10⁶ hm^-2 (M2), 7.05×10⁶ g hm^-2 (M3) and 9.00×10⁶ hm^-2 (M4). The results showed that: (1) The growth period of winter wheat under drip irrigation was shortened with the delay of sowing date. Under B3 sowing date, the growth period of Xindong 22 and Handan 5316 were 11 d shorter than B2 and 22 d shorter than B1. Density had little effect on the growth process. (2) The population size and leaf area index (LAI) increased with the increase of density and decreased with the delay of sowing date. Late sowing population tended to catch up with the normal sowing date at the later stage of growth; Population size and leaf area dynamics of B2 treated under the same density and M2 or M3 treatments in the same sowing date were the smallest with the growth process, showing better leaf regulation function. (3) With the increase of density, basal internode and barycenter height increased, basal diameter, mechanical strength and lodging resistance index decreased; With the delay of sowing date, basal internode became shorter, center of gravity height decreased, diameter increased, mechanical strength and lodging resistance index increased. Effect of density on stem character was greater than that of sowing date. In the actual production, the interaction effect of density and sowing date should be brought into full play, and the density of late sowing treatment should be appropriately increased to optimize individual growth and ensure the formation of high yield. (4) The average yield of B2 treatment was 8.09%-17.52% and 16.01%-21.07% higher than that of B1 and B3. The yields of B2M3 treatment of Xindong22 and B2M2 treatment of Handan 5316 were the highest, reaching 8 541.04 kg·hm^-2 and 9 218.08 kg·hm^-2, respectively. (5) From the perspective of population growth, Xindong22 was more sensitive to density, Handan 5316 was more sensitive to sowing date. In production, large panicle varieties should pay attention to the adjustment of sowing date under the premise of reasonable density, while multi spike varieties should pay attention to the adjustment of sowing amount under the premise of appropriate sowing date, so as to give full play to the potential of yield increase of wheat varieties.

Key words: drip irrigation, winter wheat, sowing date, density, leaf area index, stem strength