Effects of sowing time and rate on crop growth and radiation use efficiency of winter wheat in the North China Plain

Crop depends on its canopy to intercept solar radiation to drive both assimilation and water, nutrient absorption for its growth. Field experiments, involving three sowing time and three sowing rate, were conducted at Luancheng Station to investigate the effects of canopy size and development on crop growth and radiation use efficiency (RUE) of winter wheat during 2009/2010 and 2010/2011 growing seasons. The results showed that the maximum effects of sowing time on the phenological development occurred between emergence and elongation, and which was 186.0 and 162.3 doC thermal time difference during 2009/2010 and 2010/2011, respectively. Sowing time and sowing rate significantly affected above-ground biomass accumulation and RUE. Results showed that optimized sowing time and sowing rate has the potential to improve yield of winter wheat and radiation use efficiency. RUE during pre-anthesis was lower than that during post-anthesis, especially for the delayed sowing treatments which was mainly caused by the lower dry matter mobilization (DMM) and dry matter mobilization efficiency (DMME). Compared with the normal sowing time treatment, the delayed sowing time treatments had the lower DMM and DMME which indicated that the different sowing date would affect the duration of growth and then the RUE.