Development of growth model for grafted hot pepper seedlings as affected by air temperature and light intensity

The objective of this study was to develop a growth model for grafted hot pepper seedlings as affected by air temperature and light intensity. After grafted union formation, the hot pepper seedlings were cultivated in various environmental factors in terms of four levels, mean daily air temperature (17, 22, 27, and 32^◦ C) and 3 levels of light intensity (150, 350, and 550 µmol·m^−2·s−1). The growth traits were measured 0, 7, 14, 21, and 28 days after grafted union formation (DAGU). The plant height was improved, and development of leaves enhanced by higher air temperature. The number of leaves was greatest under the combination of the high temperature and high light intensity, resulting in 39.0/plant at 28 DAGU. The leaf area and dry weight showed 491.9 cm² /plant and 2.68 g/plant, respectively, at 28 DAGU under 32^◦ C air temperature and 550 µmol·m−2·s−1 light intensity. The changes of dry weight were rapidly increased under the higher air temperature and light intensity as followed by analysis of the growth curve. The beta distribution model was developed, and the relative growth rate (RGR) was simulated by the model, the maximum RGR was predicted at 0.116 g·g·d⁻¹. The RGR showed 0.113, 0.127, and 0.109 g·g·d⁻¹ at 10, 20, and 30^◦ C air temperature, respectively, and RGR was improved by 12% by increasing the air temperature by 10^◦ C, without going over 25^◦ C ADT. Results indicated that the developed growth model might be applied to optimal environmental control for maximized RGR of production of grafted hot pepper seedlings.