Phenological responses of maize to changes in environment when grown at different latitudes in China

Environmental conditions greatly affect the growth of maize. To examine differences in phenological responses of maize (Zea mays L.) to climatic factors under different environmental conditions as induced by latitude, experiments were conducted from 2007 to 2010 at 34 sites in seven Chinese provinces located in the north spring maize region of China between latitudes 35 degrees 11' and 48 degrees 08'N in the cultivation of hybrid zhengdan958 (ZD958). Latitude is an important geographical factor which significantly affects temperature, sunshine hours, and the duration of crop growth. The findings of this study indicate that for every 10 increase in the latitude, northward, the growth durations of sowing to emergence and emergence to silking were significantly increased by 0.7 d and 1.25 d, respectively as a consequence of lowering temperatures (mean, maximum, and minimum temperatures). Reproductive growth duration (silking to maturity), which was significantly correlated with the precipitation, decreased by 0.8 d with each 1 degrees increase in latitude northward. At higher latitudes, the number of growing degree days (GDD) of maize vegetative growth duration (emergence to silking) was significantly higher, and the GDD of the reproductive growth duration were significantly lower. The average photoperiod during the photoperiod-sensitive phase of maize development across all the experimental sites was 14.9 h with a range of 13.7-15.6 h. Total leaf numbers increased from 18.7 to 23.7 with an average of 21.0 across all experimental sites. Significant and positive linear relationships were found to occur between both latitude and photoperiods and latitude and total leaf number. In the north China spring maize region, the mean growth duration of ZD958 was 143.73 d, which constituted 82.8% of the frost free period, the percentage increasing with higher latitude. These findings strongly indicate that in order to ensure high and stable production of maize in the north spring maize region of China, with its limited heat resources, especially in the high-latitude regions, there is a need to cultivate short-growth-duration cultivars. (C) 2013 Elsevier B.V. All rights reserved.