2.4.1. Logistic Model

The logistic model depicts a sigmoidal curve [44] that increases gradually at first, more rapidly in the middle, and then slowly at the end before leveling off at a maximum value [45,46], such as the growth curve of DBA [47]. The model equation is as follows:

$$\mathbf{y}\_{\rm D} = a/(1 + b \exp(-kt)) \; t = \sum\_{i=1}^{n} (t\_i - 10) \tag{3}$$

where yD is the dependent growth parameter (DBA, kg ha−1); *a* denotes the uppermost asymptote, implying the theoretical upper limit of DBA growth; *b* and *k* are model parameters; *t* is the effective accumulated temperature after emergence in the present study (hereinafter referred to as the effective accumulated temperature, ◦C). Notably, *t*air, *t*canopy, *t*20, and *t*<sup>40</sup> ( ◦C), represent the effective accumulated temperature of the air, canopy, and soil at 20 cm or 40 cm of the root zone, respectively. *ti* is the day *i* value (from crop emergence) of daily average temperature of the air, canopy, or soil at 20 cm or 40 cm depth of the crop root zone. (It is calculated as 30 ◦C when *ti* exceeds 30 ◦C, and it will be calculated as 10 ◦C if the value is less than 10 ◦C [48].) *n* is the total number of days from crop emergence to harvest.
