Spatiotemporal Dynamics of Leaf Shape Coefficient of Tobacco During Field Period

To investigate the temporal and spatial dynamics of the leaf shape coefficient (α value) in field-grown tobacco, this study used Nicotiana tabacum cv. Yunyan 87 as the experimental material. By measuring the leaf length, leaf width, and leaf area under different developmental stages (temporal factor), planting densities, and leaf positions (spatial factors), the α values under various temporal and spatial conditions were calculated to clarify the characteristics and underlying mechanisms of the temporal and spatial dynamics in α values. Results showed that planting density had no significant effect on α values, while its interaction with leaf position exhibited significant effect. The average α values of different densities across leaf position showed a trend of decrease-increase-decrease-increase with the days after transplanting. Over the whole growth period, the α values for each leaf position of Yunyan 87 fluctuated between 0.512 and 0.860. Logistic model fitting results suggested that the inconsistent growth rates of leaf length and width might be the main cause of fluctuations of α values. Therefore, when calculating tobacco leaf area using α values, it is recommended to incorporate the α values corresponding to different developmental stages and leaf positions into the formula to improve the accuracy of leaf area calculation. The α values for different developmental stages and leaf positions obtained in this study, along with the proposed methods, provide a basis for more accurate and convenient leaf area calculations in tobacco production.