水肥一体化施氮水平对玉米籽粒灌浆和脱水过程的影响

Effect of Integrated Fertilization Level of Water and Fertilizer on Maize Grain Filling and Dehydration Process

以玉米品种“天赐19”为材料,于2017年和2018年在宁夏引黄灌区进行滴灌水肥一体化田间试验,设置0(N0)、90(N1)、180(N2)、270(N3)、360(N4)和450(N5)kg hm?26个氮肥水平,测定玉米百粒干鲜重,计算籽粒含水率,建立基于Logistic方程的籽粒灌浆模型并验证,分析玉米籽粒脱水动态特征,以探讨不同氮素水平对玉米籽粒灌浆和脱水过程的影响,探究明确玉米籽粒灌浆和含水量动态变化规律。结果表明:(1)滴灌水肥一体化条件下,利用2017年试验资料获得不同施氮水平玉米品种“天赐19”籽粒灌浆过程均符合Logistic方程。模型检验结果RMSE=0.203,R^2=0.954(P<0.01)。(2)各处理玉米籽粒灌浆速率均表现为先增后减的变化特征,两年试验均以施氮270kg·hm^?2处理(N3)灌浆速率最大。(3)施氮使玉米达到最大灌浆速率时间(Tmax)、最大灌浆速率(νmax)、达到最大灌浆速率时生长量(Wmax)和活跃灌浆期(T)均有所提高,N3(270kg·hm^?2)处理缩短了达到最大灌浆速率时间(Tmax),延长了灌浆持续期(t3)。(4)运用Logistic方程将各施氮处理灌浆过程划分为渐增期、速增期和缓增期3个阶段,其中速增期灌浆速率最大,对籽粒累积贡献率最高。(5)滴灌水肥一体化追施氮肥对玉米籽粒灌浆和脱水过程的调控具有明显促进作用。各处理籽粒含水率均表现为单调下降的趋势,脱水速率在生理成熟后期差异明显。两年试验均表现为270kg·hm^?2施氮处理玉米籽粒含水量较低,生理成熟后期脱水速率较快。

The field experiment of drip irrigation water and fertilizer integration was carried out in Ningxia Yellow River Irrigation District which using the maize variety“Tianci 19”as the material,and six different nitrogen fertilizer levels 0(N0),90(N1),180(N2),270(N3),360(N4)and 450(N5)kg·ha?1 in 2017 and 2018.The fresh weight of 100 grains of maize was determined,and the grain moisture content was calculated.The grain filling model based on Logistic equation was developed and verified,and the dynamic characteristics of maize grain dehydration were analyzed.To explore the effects of different nitrogen levels on maize grain filling and dehydration process,and the dynamic changes of maize grain filling and water content.The results showed that:(1)the grain filling process of the maize variety“Tianci 19”treated with different nitrogen application levels in 2017 was consistent with Logistic equation under the condition of integrated drip irrigation and water fertilization.The model test results were RMSE=0.203 and R2=0.954(P<0.01).(2)The grain filling rate of maize kernels in each treatment showed the characteristics of increasing first and then decreasing.The grain filling rate was the highest with 270 kg·ha^?1(N3)during the two-year test period.(3)Nitrogen application increased maize time to maximum grain filling rate(Tmax),maximum grain filling rate(νmax),growth at maximum grain filling rate(Wmax)and active grain filling stage(T),N3(270kg·ha?1)treatment shortens the time to maximum grain filling rate(Tmax)and prolongs the active grain filling stage(t3).(4)Logistic equation was used to divide the filling process of nitrogen application into three stages:pyramid stage,fast increase stage and slow increase stage.The grain filling rate was the highest in the fast increase stage and the grain accumulation.(5)Drip irrigation water and fertilizer integration of topdressing nitrogen fertilizer can significantly promote the regulation of maize grain filling and dehydration process.The water content of grain in each treatment showed a monotonous decreasing trend,and the dehydration rate was significantly different in the late stage of physiological maturity.In the two-year experiment,the water content of maize seeds treated with 270 kg·ha?1 nitrogen treatment was lower,and the dehydration rate was faster in the late stage of physiological maturity.