Effect of gibberellic acid on some fluorescence and chlorophyll characteristics of Cyclamen persicum Mill. seedlings under different light regimes

The use of growth regulators and light quality change are two methods to improve plant performance. Therefore, a factorial experiment was conducted in a completely randomized design. Factors included three light modes (greenhouse light (control) and LED combination light of white: red: blue as ۷۰: ۱۰: ۲۰ and ۴۰: ۴۰: ۲۰ ratios) and gibberellic acid in four concentrations (۰, ۲۰, ۴۰ and ۶۰ mg/l). At the stage of cotyledon emergence, the seedlings were exposed to LED and greenhouse light for ۴ months. Gibberellic acid was sprayed on the leaves three times from the end of the third growing month. Based on the results, in the ۶- to ۸-leaf stage, the highest amount of trapped energy flux (TR۰ / RC) was related to greenhouse light and the highest electron transfer flux in each reaction center (ET۰ / RC) was observed at the lowest concentration of gibberellic acid (zero) in greenhouse light. The lowest light fluorescence intensity at ۵۰ μs and ۲ milliseconds (F۰ and Fj) at the lowest gibberellic acid concentration under ۴۰: ۴۰: ۲۰ and the lowest light fluorescence intensity at ۶۰ ms, variable and maximum fluorescence (Fi, FV and Fm) were obtained in the same light regime. The highest content of chlorophyll b and total chlorophyll was obtained in ۴۰: ۴۰: ۲۰ light mode and the highest amount of root fresh and dry weight, root length and volume in the greenhouse and the highest leaf area in the greenhouse and a concentration of ۴۰ mg/l gibberellic acid were observed. Although the use of LED light regimes and high concentrations of gibberellic acid was beneficial in improving some physiological traits and fluorescence indices, in general, natural greenhouse light was sufficient for growing Cyclamen in the seedling production stage.  

Keywords:

Fluorescence chlorophyll , Total chlorophyll , Wet and dry root weight , Fv/Fm. , فلورسنس کلروفیل , کلروفیل کل , وزن تر و خشک ریشه , Fv/Fm