Limits to maize productivity in the North China Plain: A comparison analysis for spring and summer maize

Assessing the constraints to maize productivity and narrowing the yield gap between yield potential and actual farmers' yield in intensive maize production are essential to meeting future food demand with finite resources. A 6-year experiment that compared spring and summer maize was conducted to illuminate the limiting factors to maize productivity in the North China Plain (NCP). Drought stress in 2015 and overcast and rainy stress at the critical stage (15 d pre-silking to 15 d post-silking) in 2009, 2010 and 2016 reduced the kernel number in spring maize, and the overcast and rainy stress around silking in 2009, 2010, 2013 and 2016 led to poor pollination and low kernel number in summer maize, i.e., environmental stress at the key stage bracketing silking severely restricted the kernel number of spring and summer maize. The main limits to spring maize weight were that there was a low filling rate during the early stage and that the abundant solar and thermal resources after silking were not efficiently utilized due to heat stress; the limiting factor for summer maize weight was that the filling rate declined rapidly during the late stage because low temperature and solar radiation at late September reduced the filling rate.