关键词: 夏玉米, 有效积温, Logistic模型, 氮磷钾, 株高, 叶面积指数

Abstract:

【Objective】In order to explore the growth dynamic prediction model and its characteristic parameters of summer maize plant height and leaf area index (LAI) based on effective accumulated temperature with different nitrogen, phosphorus and potassium treatments, in order to provide a theoretical basis for using effective accumulated temperature to quantitatively simulate the growth and development of summer maize.【Method】Based on the two-year field experiment in Langfang, Hebei province (2019-2020), this study uses Zhengdan 958 as the experimental material and is divided into three single-factor fertilizer efficiency experiments of nitrogen, phosphorus, and potassium. Each factor is set at 4 levels, respectively no fertilizer, low fertilizer, moderate fertilizer and high fertilizer treatments. The Logistic mathematical model was used to fit the dynamic equation of summer maize plant height and leaf area index based on effective accumulated temperature under different nitrogen, phosphorus and potassium nutrition levels, and the growth rate curve and its characteristic parameters were used to quantitatively analyze the growth and development characteristics of summer maize.【Result】(1) Under the conditions of this experiment, compared with other treatments, the maximum summer corn plant height was the largest in the treatments with proper amount of fertilizer (N2, P2 and K2). Excessive application of potassium fertilizer has a significant inhibitory effect on the maximum plant height of summer corn. Appropriate fertilization treatment of summer maize plant height requires accumulated temperature of 952.43-958.83℃·d. proper fertilization can effectively increase summer maize leaf area index, and excessive or insufficient nutrients will affect the formation of leaf area. Appropriate fertilization treatment of summer maize leaf area index required accumulated temperature to enter the plateau period is 849.18-952.43 ℃·d.(2) The fit R² of the summer maize plant height and leaf area index equations established with effective accumulated temperature as the independent variable under each fertilization treatment condition were 0.9949-0.9970 and 0.9840-0.9939, respectively, and the equations reached extremely significant levels and had biological significance. The correlation coefficient (r) between the simulated value and the measured value based on the plant height fitting equation of the effective accumulated temperature is between 0.9961-0.9983; the r of the simulated value and the measured value of the leaf area index fitting equation based on the effective accumulated temperature is 0.9815-0.9981.(3) Under various fertilization conditions, the growth rate of summer maize plant height and leaf area index showed a “single-peak curve”. Under the conditions of appropriate fertilization, the growth rate curve showed the characteristics of rapid rise and fall. The growth rate curve of the treatments without nitrogen fertilizer, phosphate fertilizer and potassium fertilizer showed the characteristics of slow rise and slow decline. (4) Under the condition of appropriate fertilization, the accumulated temperature of summer maize plant height entering the rapid growth period, the accumulated temperature entering the slow growth period and the accumulated temperature reaching the maximum growth rate are 394.17℃·d, 776.63℃·d and 585.40℃·d, respectively, which were significantly different from N0, P0 and K0 treatment. The maximum growth rate and average growth rate of plant height in the rapid growth period are 0.4907 cm·(℃·d)^-1 and 0.4302 cm·(℃·d)^-1, respectively, which are not significantly different from N0, P0 and K0 treatment. (5) Under the condition of appropriate fertilization, the accumulated temperature of summer maize leaf area index entering the rapid increase period, the accumulated temperature entering the slow increase period and reaching the maximum growth rate are 609.69℃·d, 855.08℃·d and 732.38℃·d, respectively. The maximum growth rate of leaf area index and the average growth rate of rapid increase period are 0.0135℃·d and 0.0118℃·d, respectively.【Conclusion】Insufficient nutrient supply can increase the effective accumulated temperature required for summer corn plant height and leaf area index to enter the plateau period. The Logistic model based on the effective accumulated temperature can well simulate and predict the dynamic changes of summer maize plant height and leaf area index under different N, P, and K treatments. The degree of fit and stability of the fitting equation under the condition of proper fertilization is better than that of the fitting equation with excessive or insufficient nutrients. Compared with the treatment with no fertilization, the plant height and LAI of summer corn reach the required accumulated temperature during the critical period (accumulated temperature required to enter the rapid increase period, accumulated temperature required to enter the slow increase period, and accumulated temperature required for the maximum growth rate). The growth rate (the maximum growth rate, the average growth rate during the rapid growth period) has decreased significantly. This study provides a theoretical basis for the effective accumulated temperature to quantitatively simulate the growth and development of summer maize.

Key words: summer maize, effective accumulated temperature, Logistic model, NPK, plant height, LAI