[Maize growth and its responses to heat condition in Northeast China]

Taking 3 maize cultivars (Danyu 39, Yuandan 29, and Longdan 13) as test materials, a field experiment was conducted to study their growth characteristics and responses to air temperature under the conditions of early, medium and late sowing. For the three cultivars, the days from sowing to seedling emergence under early, medium and late sowing were averagely 13, 11 and 8 d, respectively, and the seedling emergence rate was the fastest when the mean air temperature was about 18 degrees C. Higher or lower air temperature would decrease the seedling emergence rate. The test cultivars had less difference in the days from seedling to jointing, which was slightly affected by air temperature. Compared with Danyu 39 and Yuandan 29, the late-maturing Longdan 13 had an increased growth rate from jointing to mature stage, and thus, the days for mature shortened markedly. For all the three maize cultivars, the days from jointing to mature tended to decrease with increasing air temperature. The dry matter accumulation rate in whole growth period, grain yield, and 100-seed mass were in the order of Danyu 39 > Yuandan 29 > Longdan 13.