International Journal of Advance Agricultural Research
ISSN: 2053-1265
Vol. 7(2), pp. 21-31, March 2019
doi.org/10.33500/ijaar.2019.07.003



Influence of Gigaspora margarita and Acaulospora tuberculata on tolerance to Phytophthora megakarya in Theobroma cacao under plant nursery conditions

DJOCGOUE Pierre François2,4, SIMO Claude1,4*, MINYAKA Emile3,4, TASSONG SAAH Denis1,
NJONZO-NZO Stephanie Alvine1 and TAFFOUO Victor Desire1

1Department of Plant Biology, Faculty of Science, University of Douala P. O. Box 24157, Douala, Cameroon.
2Department of Plant Biology, Faculty of Science, P. O. Box 812, Yaoundé, Cameroon.
3Department of Biochemistry, Faculty of Science, University of Douala, P. O. Box 24157 Douala, Cameroon.
4Laboratory of Plant Physiology, Department of Biological Sciences, Higher Teacher’s Training College, P. O. Box 47, Yaounde, Cameroon.

*To whom correspondence should be addressed. E-mail: simoclaude@yahoo.fr.

Received 04 February, 2019; Received in revised form 10 March, 2019; Accepted 14 March, 2019.

Abstract


Keywords:
Theobroma cacao, Phytophthora megakarya, Gigaspora margarita, Acaulospora tuberculata, Tolerance.


The effect of Gigaspora margarita and Acaulospora tuberculata inoculation on the tolerance of hybrid genotypes of cocoa (Theobroma cacao L.) to stress caused by Phytophthora megakarya, was studied in a greenhouse and thereafter in the laboratory. An assessment of the susceptibility of parental and hybrid genotypes of the family F79SA (T79/501x SNK413) was performed after artificial infection with P. megakarya in the absence and presence of arbuscular mycorrhizal (AM) fungi by the leaf disc test. Variance analysis of necrotic surfaces showed a significant date effect and genotype effect (P>0.05) in the offspring. In addition, 68% of hybrid genotypes had a lower necrosis surface than the most active parent in the absence of the AM fungi. Under the control of AM fungi, 86% of hybrid genotypes were very tolerant and 14% were tolerant on day 7. The map of tolerance analysis under the control of AM fungi shows a strong dominance of the black color in all hybrid genotypes thus translating very small necrotic surfaces. These results indicate that the G. margarita and A. tuberculata significantly reduced susceptibility to P. megakarya in T. cacao. Although, the progeny came from fathers tolerant to P. megakarya, there tend to be many incidents with susceptibility to this fungus.

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