Study on the Theoretical Model of Watering Ratio and Drought Resistance under Proportional Irrigation of Maize

【Objective】 To research and establish a theoretical model of the relationship between watering ratio and drought resistance in the hope of providing a theoretical basis for accurate identification of drought resistance under the condition of proportional irrigation of corn. 【Methods】 From 2017 to 2019, 12 hybrids were treated with 6 water gradients under the condition of reducing the proportion of irrigation. Each treatment area was irrigated 8 times in the whole process. The watering for emergence was 675 m³/hm², and the water for the remaining 7 times was reduced according to the proportion of 100%, 80%, 60%, 40%, 20% and 0% to form different drought stress intensity. Based on the equivalent transformation and derivation of the lack irrigation model, the proportional of irrigation model was established. The model was validated with the results of 3 years of experiments. 【Results】 A theoretical model of the relationship between water supply rate and corn drought resistance was established, and the model was γ= Φ ^k (Φ^k + ${\Phi }_h^k$), which could describe maize hybrid in nonlinear power exponential saturation curve drought resistant coefficient (γ) changing with watering ratio(Φ). After being fitted and verified, the correlation coefficient between the predicted value and the actual value of 12 corn hybrids was 0.973-0.995 (mean 0.987), and the fitting reached an extremely significant level (P <0.01, 0.917). The RPD value of residual prediction deviation fitted by the model was 3.914-9.485, which was greater than 3.0, which meant the model was a good fitting. 【Conclusion】 The model of watering ratio and drought resistance of maize hybrid can be used in the precise identification of maize drought resistance under proportional irrigation. The parameters, half-yield watering ratio (Φ_h) and water sensitive coefficient (k) have definite biological significance, which are two important indexes of maize drought resistance. Maize varieties with small values of two parameters have relatively stable drought resistance.