Effects of Temperature, Light Intensity and DIF on Growth Characteristics in Platycodon grandiflorum

Abstract

Bellflower (P. grandiflorum) has been an important medicinal plant since the ancient time. In the present study, we aimed to determine the effects of temperature, light intensity, and the difference between day and night temperature (DIF) on plant leaf and root morphology in P. grandiflorum. Plants were grown for five months in a Biotron room with a constant temperature (15, 20, 25, and 30°C) as well as natural light and shading condition. In the natural light, the lowest plant height (23.8 cm) was observed at 30°C compared than low-intensity light. Shading caused inhibition in the leaf length and leaf width compared than natural light condition. The number of branches decreased significantly (p≤0.05) under the low light intensity condition except for the temperature at 30°C. Root morphology was significantly affected by different levels of light intensity treatment in P. grandiflorum for. duplex. However, the highest root length (8.2 cm) and diameter (7.8 mm) was observed when the plants were grown under high light intensity. In P. grandiflorum with green petal, temperature and shading showed significant changes in plant morphology. However, the plant height under the natural light condition was in the range of 45.8~48.2 cm in the temperature range of 15~25°C. The negative DIF at 15/30°C decreased growth and development of both P. grandiflorum for. duplex and P. grandiflorum with green petals plants as reflected in the lowest plant height, leaf width, leaf length, number of branches, root length, root diameter, and root fresh weight. The present study concluded that the fluctuation of temperature and light intensity affects both leaf and root morphology, and the DIF has a significant influence on the growth and development of bellflower.