Morphological and Physiological Responses of Sweet Pepper (Capsicum annuum L.) to Varying Light Intensities

Abstract

This study was conducted in the Plant Laboratory of the Department of Biology – College of Education, University of Samarra, beginning in October 2024, to study the effect of light stress on the vegetative and chemo-biological traits of sweet pepper (Capsicum annuum L.) under varying intensities of light stress. The experiment was designed based on the One-Factor Experimental Design with three replicates per treatment unit. The control group was exposed to a light intensity of 55 µE, while the four other experimental groups were subjected to light intensities of 5 µE, 370 µE, 780 µE, and 1600 µE, respectively. The plants were exposed to a photoperiod of 16 hours of light and 8 hours of darkness at a temperature of 25 °C, with irrigation applied using the bottom watering method to avoid root fungal infections.
The results of the vegetative characteristics showed that the highest values for leaf area, fresh weight, stem length, stem diameter were recorded at the 780 µE light intensity treatment, with values of 16.233 cm², 6.433 g, 17.266 cm, 3.0 mm,. The highest root length (13.566 cm) was observed at the 370 µE treatment, while the highest dry weight (0.773 g) was recorded at the 1600 µE treatment. These findings suggest that moderate to high light intensities promote optimal vegetative growth in Capsicum annuum L., which may have practical implications for controlled environment agriculture.