[Effects of extremely-late sowing on the grain yield, nitrogen uptake and utilization, and grain protein content in...

In order to explore the cultivation techniques for high yield, quality and nitrogen use efficiency of wheat and guide the production practice of late sowing, a two-year experiment of different sowing times and plant densities in fixed plots was conducted from October 2012 to June 2014. Weak-spring cultivar of Yanzhan4110 (YZ4110) and semi-winter cultivar of Aikang58 (AK58) were sowed with two cropping patterns: Normal sowing (sowing in the middle of October, 2.4×10⁶ plants·hm^-2) and extremely-late sowing (sowing in the middle of November, 6.0×10⁶ plants·hm^-2). The nitrate-N content in 0-40 cm soil, the nitrogen (N) uptake and utilization, grain yield, grain protein content and N uptake efficiency in winter wheat were investigated. Compared with normal sowing, extremely-late sowing significantly increased the nitrate-N content in 0-40 cm soil at jointing and anthesis stages, which in turn promoted the N uptake and accumulation of plants after jointing stage and increased the N distribution ratio of spikes at maturity. As a result, the grains with extremely-late sowing had higher protein contentin both YZ4110 and AK58, and higher protein yield and N uptake efficiency in YZ4110 than that with normal sowing. However, the effects of extremely-late sowing on grain yield were different in the two cultivars. Compared with normal sowing, extremely-late sowing clearly raised the grain yield of YZ4110, but significantly decreased that of AK58. These results indicated that extremely-late sowing is an alternative cropping technique to increase grain yield and protein content for winter wheat in irrigation zones through maintaining the soil N supply after jointing stage and increasing N uptake efficiency.