EXTRATO DE Caesalpinia ferrea NO MANEJO DA MANCHA MARROM DE ALTERNARIA EM MUDAS DE TANGERINA ‘DANCY’

Abstract

The tangerine 'Dancy' (Citrus tangerine Hort . Ex Tanaka ) is affected by various diseases , especially the brown spot Alternaria (MMA), caused by Alternaria alternata f . sp. citri, which has been promoting reduction in productivity and causing serious damage in Brazilian planting. The main form of disease control is the use of synthetic fungicides, then, the search for natural products, which do not degrade the environment, is shown as a promising alternative. This study aimed to verify the potential of Caesalpinia ferrea extract on control of MMA in Tangerine ‘Dancy’ seedlings. The experiment was conducted at Plant Pathology Laboratory in Agricultural Sciences Centro de Ciências Agrárias, Universidade Federal da Paraíba, Campus II, Areia-PB. The seedlings with 30 days of culture were purchased from a commercial planting in Remigio-PB (6° 54′ 10″ S, 35° 50′ 2″ W). The experimental setup the seedlings were sprayed with C. ferrea extract at concentrations of 10; 100; 500 e 1000 μg/mL; fungicide (8 g/100 L), and sterilized destilled water to point of run-off. Then were placed in a moist chamber and after 24 hours was performed inoculation of A. alternata (105 conidia/mL). After 96 hours were done evaluations of severity and incidence of the disease. The design was completely randomized, in 6 treatments with 25 replications, totaling an experimental area of 150 seedlings. To determine the activity of the enzymes phenylalanine, ammonia-lyase , peroxidase and polyphenoloxidase, were removed leaves/repetition before and 23 days after treatment application. Regression test was used for the concentrations of the extracts when evaluated the incidence and severity and the Dunett test at P < 0.05 probability to compare the means of enzymatic analysis. The concentrations of 100 and 500 μg/mL of C. ferrea extract decreased incidence of A. alternate 27 and 45%, respectively, and lower disease severity (8 and 4%). Just phenylalanine ammonia-lyase showed a significant increase in its activity, the highest values occurring at concentrations of 100 and 1000 mg/mL of C. ferrea extract.