Model Construction of Rainfall Interception by Maize Canopy

Rainfall is the main water source of crops. Crops maintain their normal growth and development by absorbing water from the soil. However, the role of rainfall is often overestimated in water resource evaluation and farmland water balance research because the rainfall interception effect of crop canopy is not considered. It is difficult to calculate crop interception quantitatively, which seriously restricts the impact assessment of rainfall on crops. Therefore, in order to determine the interception effect in different growth stages of maize under different rainfall, the rainfall interception experiment of maize is carried out at Jinzhou Agricultural Meteorological Experimental Station of Liaoning Province in 2018. A total of 10 rainfall levels (rainfall over 20 mm is designed for the measurement of saturated interception) and 8 leaf area indexes (representing 8 different growth periods) are examined in the experiment. The rainfall interception effect of maize canopy is systematically analyzed by simulation. Results show that under certain rainfall, the relationship between the interception of maize canopy and leaf area index conforms to the relationship of quadratic polynomial, exponential function and power function, among which the quadratic polynomial has the highest explanation rate. Under the assumption of fixed leaf area index, the rainfall interception of maize canopy is in accordance with the quadratic polynomial, exponential function, power function and logarithmic function. When leaf area index is above 3, the explanation rate of power function is the highest, and the relationship between saturated interception of maize and leaf area index is in accordance with the quadratic polynomial, exponential function and power function, among which the explanation rate of quadratic polynomial is the highest. The comprehensive leaf area index and rainfall analysis indicate a positive correlation between canopy interception and the square of leaf area index and the logarithm of rainfall. According to the traditional planting mode of maize in China, the maximum leaf area index of high-yield maize is generally about 5-6. Therefore, the maximum interception of a rainfall process is usually 1.5-2.3 mm. When leaf area index is less than 1, the rainfall interception of maize can be ignored. Results are of practical significance for the evaluation of the effectiveness of rainfall resources and the study of farmland water balance.