Abstract:

To apply nitrogen fertilizer more reasonably and improve nitrogen use efficiency in planting high-efficiency maize varieties, low-nitrogen and high-efficiency type maize variety ‘Jingnongke 728’ and high-nitrogen and high-efficiency type maize variety ‘Xianyu 335’ were used as materials, five nitrogen treatments were set up: N1(120 kg/hm²), N2(180 kg/hm²), N3(240 kg/hm²), N4(300 kg/hm²), and NCK (360 kg/hm², nitrogen application rate in local field production). The photosynthetic characteristics and grain filling characteristics of the two maize varieties were measured in this experiment. The results showed that the photosynthetic rate of ‘Jingnongke 728’ under N2 treatment at jointing stage and filling stage was significantly higher than that under NCK, and the transpiration rate at jointing stage was significantly higher than that under NCK, the intercellular carbon dioxide concentration at the tasseling stage was lower than that under NCK, and the difference was significant. The photosynthetic rate, transpiration rate and stomatal conductance of ‘Xianyu 335’ under N4 treatment were significantly higher than those under NCK at the silking stage, and the photosynthetic rate was significantly higher than that under NCK at the filling stage. The intercellular carbon dioxide concentration during tasseling and filling stage was significantly lower than that under NCK. The grain-filling rate of ‘Xianyu 335’ under N4 treatment was significantly higher than that under NCK. Therefore, the optimum nitrogen application rate of ‘Jingnongke 728’ is about 180 kg/hm² (N2), and that of ‘Xianyu 335’ is about 300 kg/hm² (N4).

Key words: maize, nitrogen application rate, eastern Hebei Province, photosynthetic characteristics, grain filling characteristics