Evaluation of the Behavior of Cashew Genotypes with Regard to Bacterial Disease in Agroforestry Farms in Northern Côte d'Ivoire

Abstract

Notwithstanding the inflows of currency for the populations who practice it, the cultivation of the cashew tree contributes to strengthening the forestry agrosystem in Côte d'Ivoire. However, this culture, with multiple interests, is confronted with attacks from parasites including bacterial disease. Bacterial disease causes extensive damage to vegetative organs as well as fruits and causes yield losses. The objective of this study is to assess the behavior of cashew genotypes in relation to the severity and incidence of bacterial disease in the context of agroforestry production in Côte d'Ivoire.
 To achieve this objective, 1.200 branches were observed to assess the tolerance or sensitivity of 30 cashew trees in agroforestry orchards of cashew trees in the localities of Korhogo, Sinématiali and Boundiali. These cashew genotypes were selected and geolocated. The factor studied is the cashew genotype, composed of 30 cashew genotypes, with 6 modalities which are the severity index of bacterial disease on leaves, twigs and nuts, the incidence of bacterial disease. bacterial disease on leaves, twigs and nuts. The data collected that are the index of severity of bacterial disease on leaves, twigs and nuts, the incidence of bacterial disease on leaves, twigs and nuts have made the subject to descriptive analysis and PCA. The ascending hierarchical classification (HAC) and multivariate analysis completed the data analysis. The results obtained revealed three groups of cashew trees. Those of group 3 made up of twelve (12) genotypes, namely SYDN, SDYY, SDYN and KBSD coming from the localities of Sinématiali and Korhogo, differ from the others by a weak infection of the nuts (8.67 ± 2.74). The genotypes in this group are more resilient and their development in an agroforestry system could help promote agroecological management of bacterial disease, improve and intensify agroforestry practices in C. d'Ivoire.

Distribution of Bacterial Disease in the Main Mango Production Areas of Côte d'Ivoire

“…In each orchard selected, a block of one-hectare plots comprising 100 mango trees spaced 10 m apart from each other was demarcated. At the level of each plot, 1440 branches of 36 mango trees were evaluated according to the diagonal and median method [10]. These tree populations were studied using the traveling inventory method combined with the diagonals and medians method.…”

“…This evaluation focused on ten (10) branches marked on either side of the NS and EO axes to be viewed and carried by hand. A scale adapted to that of Bhagwat et al [17] was used to qualify the level of incidence of bacteriosis on each tree Cardoso et al [13] This six-level scale (0-5) is defined as follows: 0 (no symptoms); grade 1 (1 to 10%: low incidence); grade 2 (11-20%: moderate incidence); grade 3 (21-30%: medium or intermediate incidence); grade 4 (31-50%: high incidence); grade 5 (> 50%: very high incidence).…”

“…Excel 2016 software was used for data entry and for the construction of graphs [10]. Statistica version 10 software was used for descriptive analysis of the data, for comparison tests of means [18] Pearson's correlation test was performed with SPSS 16.0 software to establish a relationship between the incidence of bacteriosis and agromorphological parameters [10].…”

“…Excel 2016 software was used for data entry and for the construction of graphs [10]. Statistica version 10 software was used for descriptive analysis of the data, for comparison tests of means [18] Pearson's correlation test was performed with SPSS 16.0 software to establish a relationship between the incidence of bacteriosis and agromorphological parameters [10]. Finally, principal component analysis (ACP) and ascending hierarchical classification (CHA) supplemented by multivariate analysis (MANOVA) were performed to structure the mango orchards into different groups [18].…”