The impact of melatonin and glutathione on the physiological characteristics of the hot pepper Capsicum annuum L. grown under cadmium pollution

Abstract

The experiment was conducted in pots within the plastic house of a nursery located in the Al-Muqdadiya district, situated to the north of Baqubah, the central city of Diyala governorate, which lies 90 km northeast of the capital, Baghdad. This study focused on Capsicum annuum L, specifically the Barbarian F1 class of Indian origin, during the autumn season. The objective of the experiment was to investigate the effects of melatonin and glutathione treatments on the physiological characteristics of Capsicum annuum L grown under conditions polluted with cadmium. The research followed a Randomized Complete Block Design (R.C.B.D.) with three replicates. Three treatments were applied: cadmium, added to the soil at concentrations of 0 and 15 mg.kg soil-1, and melatonin and glutathione, applied to the leaves at concentrations of 0, 50, and 100 mg.L-1. The results revealed a significant decrease in fruit carbohydrate content and catalase enzyme activity when treated with cadmium at a concentration of 15 mg.kg soil-1. However, applying melatonin at concentrations of 50 and 100 mg.L-1 led to a significant increase in fruit carbohydrate and protein content, along with a notable rise in catalase and peroxidase enzyme activities. The concentration of 100 mg.L-1 demonstrated the highest mean values for these features. Moreover, the study demonstrated a significant increase in fruit carbohydrate and protein content, as well as catalase enzyme activity, when plants were treated with glutathione at concentrations of 50 and 100 mg.L-1. The highest mean values for these features were observed when plants were treated with glutathione at a concentration of 100 mg.L 1.