Dynamic Simulation and Allometric Relationship of Tobacco Stem Growth

Exploring the growth dynamics of pitch and circumference of tobacco stem and the growing relationship can provide a scientific basis for rational plant shape of tobacco. In this study, Zhongyan100 was selected to investigate the growth traits of pitch and circumference from the rosette stage to the flower-bud appearing stage. Richards growth dynamic model was used to simulate the growth dynamics of the pitch and circumference with different positions, and standardized major axis (SMA) method was used to analyze the allometric relationship between pitch and stem circumference. The results showed that:(1) the Richards growth dynamic model of the main stem pitch and circumference of all positions conforms to the "S" type growth curve (R²>0.9); among them, the Richards growth dynamic simulation of pitch at the middle leaf position is typical "S" type curve; and the RMSE test shows high precision and accuracy; (2) The order of maximum value of main stem pitch was upper > middle > lower, and the order of maximum value of main stem circumference was lower > middle > upper; (3) The standardized major axis method indicates showed that there is a significant allometric growth relationship between the pitch and circumference at different positions and different stages (p <0.001). The allometric slope was upper > middle > lower, and rosette stage > flourishing stage > flower-bud appearing stage. The above results showed that the Richards equation and standardized major axis could accurately simulate the tobacco main stem growth dynamic and growing relationship, verify the rule that the stem of tobacco is mainly pitch elongation at first, and then circumference thickening. Considering the tobacco plant type characteristics, the rosette stage and flourishing stage played a key role in stem elongation, while the flower-bud appearing stage played a key role in stem thickening. The results of this study will help to establish a reasonable plant type and improve the lodging resistance of tobacco plants