| To investigate the yield characteristics and temperature and light use efficiency of early maturing wheat varieties under late sowing after rice stubble and early harvest in the southwestern, a two factor split plot experiment was designed, with sowing date as the main plot namely, early sowing(S1, 23 October), regular sowing(S2, 30 October), late sowing for 7 d(S3, 6 November), late sowing for 14 d(S4, 13 November), and late sowing for 21 d(S5, 20 November), and planting density as the split plot(2.50×106, 3.25×106, 4.00×106 plants·hm-2), to study the effects of sowing date and planting density on yield and its components, dry matter accumulation and translocation, filling characteristics and temperature, light use efficiency of winter wheat. The results showed that there was no significant difference in wheat yield among S2, S3 and S4, while S1 and S5 reduced yields by 7.6% and 32.2%, respectively, compared to S2. There is no significant difference in yield between different planting densities. Late sowing can shorten the entire growth period of winter wheat, and reduce the effective accumulated temperature and daily average temperature before jointing. Compared with S2, S3, S4 and S5 reduced the accumulated temperature during wheat growth by 65.4, 84.1 and 93.8 ℃, and the daily average temperature by 1.3, 2.4 and 3.7 ℃, respectively. Late sowing increased the daily average temperature during jointing to booting and booting to flowering stages, reduced the effective number of spikes, and increased the number of grains per spike. Late sowing wheat has abundant temperature and light resources after flowering, manifested by an increase in daily average temperature and radiation after flowering, an increase in dry matter accumulation after flowering, an acceleration in grain filling rate, a shortened duration of grain filling, and stable grain weight. Increasing planting density increased the contribution rate of pre flowering dry matter, reduced the duration and activity time of grain filling, and had a relatively small impact on the grain filling rate. Moderate late sowing can improve temperature use efficiency, with an increase rate of 2.24% and 8.02% for S3 and S4, respectively, compared to S2. In summary, late sowing winter wheat can achieve stable yield by increasing the number of grains per ear, and the accumulation amount and transport efficiency of dry matter after flowering can be improved. |
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