Response of Catharanthus roseus cv. ‘Pacifica XP’ to Adding Copper and Foliar Spraying with Benzoic and Salicylic Acids

Abstract

The experiment was carried out in a greenhouse at the University of Diyala’s Research Station for the Department of Horticulture and Landscaping in the College of Agriculture during the 2020–2021 academic year. Experiments were conducted on Catharanthus roseus cv. ‘Pacifica XP’ from November 24, 2020, to June 1, 2021, and the effects of adding copper at 0, 30, 45, and 60 mg L-1, and foliar spraying with benzoic and salicylic acids at concentrations of 20 and 40 mgL-1, along with spraying with distilled water as a control treatment, were analyzed. A factorial experiment (54) with three replications was conducted using the randomized complete block design (RCBD). Results showed that all vegetative and biochemical characteristics-including leaf number, leaf area, chlorophyll content, nitrogen, phosphorus, potassium, copper content, total carbohydrates, phenolic acids, vincristine, vinblastine, vindeline, and catharanthine content-were significantly improved by the addition of copper at a concentration of 60 mg L-1. Number of leaves, leaf area, dry weight of leaves, percentage of nitrogen and potassium in the leaves, copper content in the leaves, phenolic acid content in the leaves, and vinblastine content in the leaves were all found to improve after foliar spraying with benzoic acid at a concentration of 40 mg L-1. The number of leaves, percentage of potassium, content of copper in the leaves, and phenolic acid content in the leaves were all significantly affected by the interaction treatments between the concentrations of copper, benzoic, and salicylic acids, with the interaction treatment BA40Cu60 yielding the best results. The characteristics of chlorophyll content in leaves, nitrogen and phosphorous percentages, total carbohydrates percentages, and vincristine, vinblastine, vindeline, and catharanthine leaf contents all favored the SA40Cu60 interaction treatment, whereas the vincristine content favored the BA20SA40 interaction treatment.