| In order to increase wheat yield and select suitable sowing method and seeding rate of wheat in wheat-cotton intercropping system,a split plot experiment involving two sowing methods (broadcasting and drilling) and four seeding rates (187.5 kg·hm-2,225.0 kg·hm-2,262.5 kg·hm-2,300.0 kg·hm-2 ) was designed to study the effect of sowing methods and seeding rates on grain filling and yield traits of wheat. The results showed that compared with drilling,broadcasting increased grain filling period by 3.3,0.6 d for marginal and inner rows,respectively,but decreased the average and maximum grain-filling rate by 0.18,0.26 mg·grain-1·d-1 for marginal rows,and delayed the appearing time of the maximum grain-filling rate by 0.2 d. For the inner rows,broadcasting increased the theoretical final grain weight by 1.7 g obviously due to the increase of the average and maximum grain-filling rate by 0.02,0.04 mg·grain-1·d-1,respectively,at the same time delayed the appearing time of the maximum grain-filling rate by 0.6 d. Compared with the seeding rate of 187.5 kg·hm-2 ,the sustainable filling period at seeding rate of 300.0 kg·hm-2 was prolonged by 2.8 and 1.8 d,2.6 and 2.2 d respectively for marginal rows,inner rows of broadcasting and drilling,the average grain-filling rate was decreased by 0.10 and 0.02,0.11 and 0.10 mg·grain-1·d-1 and the maximum grain-filling rate was decreased by 0.15 and 0.03,0.15 and 0.15 mg·grain-1·d-1 ,the appearing time of the maximum grain-filling rate was prolonged by 0.7 and 0.5 d,0.9 and -0.8 d. And the theoretical final grain weight was decreased by 1.5 and 3.1,1.1 and 6.5 g. Broadcasting significantly increased wheat yield of inner rows by 405.0 kg·hm-2 due to the significantly increased panicle number per unit area by 1 460 thousand panicle·hm-2,also the increased grain number per ear by 1.4 and thousand-grain weight by 0.2 g of inner rows. The difference of panicle number per unit area,grain number per ear,thousand-grain weight and wheat yield between drilling and broadcasting was not significant. The yield of broadcasting increased by 5.1% compared with drilling. With the increase of seeding rate,the panicle number per unit area increased but grains per ear and thousand-grain weight decreased. For broadcasting the yield was the highest at the seeding rate of 225.0 kg·hm-2 and for drilling it was at the seeding rate of 262.5 kg·hm-2. In wheat-cotton intercropping system the suitable sowing method was broadcasting and the optimum seeding rate was 225.0 kg·hm-2. |
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