Evaluación de la capacidad antagónica in vitro de dos cepas de Trichoderma spp. frente a Moniliophthora roreri (Cif. & Par.) y Phytophthora spp. en mazorcas de Theobroma cacao L.

The general objective of the present investigation was: To evaluate the in vitro antagonistic capacity of two strains of Trichoderma sp. against phytopathogens of cocoa pod. The present study was carried out in the Phytopathology Laboratory of the Faculty of Agricultural Sciences of the Technical University of Babahoyo, located at Km 7.5 of the Babahoyo - Montalvo Road, province of Los Rios. For the antagonism tests of the fungus Trichoderma spp. against the phytopathogens Phytophthora spp. and M. roreri isolated from cocoa fruits, two strains (probably different species) were used. One strain 1 was isolated from plantations of T. cacao L. (cacao) from the Tropical Experimental Station Pichilingue of INIAP, and a second strain 2 was isolated from a crop of Capsicum annuum L. (bell pepper) in the canton of Portoviejo, province of Manabí. Ten treatments were applied, based on the dual combination of antagonistic fungi and phytopathogenic fungi, plus absolute controls, with five replicates per treatment, distributed in a complete randomized design (CRD). The experimental unit consisted of a 90 mm diameter Petri dish, adjusted to pH 5.5 and incubated at 25 ± 1 ºC, with alternating periods of 12 hours of light and 12 hours of darkness. For the determination of significant statistical differences between treatments for the variables analyzed, the Tukey test was applied at 5%. The following variables were evaluated: Radial growth rate, radial growth mean, radial growth rate, antagonist-pathogen contact time, radial growth inhibition percentage, substrate competition and mycoparasitism. The analysis of the results revealed the following: The isolates of M. roreri and P. spp presented the pathogenic and morphological characteristics desirable to develop the antagonism tests. Strain 1 (T. spp) and strain 2 (T. spp) presented excellent antagonistic characteristics on the control of M. roreri and P. spp. In relation to the dual confrontation, strain 2 (T. sp.) (39. 2 mm) presented a high accumulated radial growth on M. roreri (5.8 mm), in contrast to strain 1 (T. sp.) (37.2 mm) which presented a low accumulated radial growth on M. roreri (7.2 mm). In the dual confrontation, the treatment with strain 2 (T. sp) (19.6 mm) showed a higher mean radial growth over the pathogen M. roreri (2.9 mm) and the dual confrontation with strain 1 (T. sp) (18.6 mm) showed a higher mean radial growth over the pathogen M. roreri (3.9 mm). In the dual confrontation, the treatment with strain 1 (T. sp) (1.53 mm.h-1) showed a higher radial growth rate over the pathogen M. roreri (0.13 mm.h-1). In the dual confrontation with strain 1 (T. sp) (3.66 mm.h-1), it presented a superior radial growth rate over the pathogen P. spp (0.22 mm.h-1). In relation to the dual confrontation with strain 2 (T. sp) (1.63 mm.h-1), which showed a superior radial growth rate over the pathogen M. roreri (0.04 mm.h-1). A superior growth rate was obtained with strain 2 (T. sp) (3.64 mm.h-1) over the pathogen P. spp (0.84 mm.h-1). In the dual confrontation, the radial growth inhibition effect of strain 2 (T. spp.) was higher on the pathogen M. roreri (84.44 %), while for the pathogen P. spp (83.11 %) it was lower, unlike strain 1 (T. spp.) which showed a lower radial growth inhibition effect on M. roreri (81.33 %) and on P. spp (82.22 %). The radial growth inhibition effect of strain 1 (T. spp.) on the pathogen P. spp (84.44 %) was statistically equal to the radial growth inhibition effect of strain 2 (T. spp.) on P. spp (84 %). The mechanisms of antagonism found were mycoparasitism and competition for space and nutrients for T. spp. strains, located in grade 1 of the antagonism scale.

• Κύριος συγγραφέας: Medina Pinoargote, Marcos Alejandro (author)
• Μορφή: masterThesis
• Έκδοση: 2022
• Θέματα: Fitopatógenos; Antagonismo; Eficacia; Cacao
• Διαθέσιμο Online: http://dspace.utb.edu.ec/handle/49000/14659