The effects of intraspecific competition and light transmission within the canopy on wheat yield in a wide-precision planting pattern

The wide-precision planting pattern has become widely used in the North China Plain as a practice for increasing wheat yield. However, the effects of tillering development and light transmission within canopy on wheat yield under different sowing widths have not been clearly described. Therefore, a two-year experiment was conducted, including four different seeding widths (6 cm, W6; 8 cm, W8; 10 cm, W10; 12 cm, W12) and the traditional planting pattern with seeding width of 4 cm (W4). The results indicated mainly positive effects by the reduced intraspecific competition, specifically all three yield components of W6 and W8 were higher than those for W4. The configurations with more than 10-cm seeding width were mainly affected by the negative effect of a relative homogeneous canopy, leading to the weakened light transmission, leaf senescence, and reduced grain number per spike. Finally, the yields of W6 and W8 were significantly higher than that of W4, whereas the yield in W12 was lower (though not significantly) than W4. In wheat production, therefore, the appropriate seeding width of 6-8 cm is recommended for farmers, whereas the too wide seeding width, with more than 10 cm, should be avoided.