Variability and estimating in fruiting of shea tree (Vitellaria paradoxaC.F. Gaertn) associated to climatic conditions in West Africa: implications for sustainable management and development

Abstract

Shea tree (Vitellaria paradoxa) is one of the main native oil plants with high economic value in Africa. Its fruits are used for food, medicinal, cultural and exportation purposes. However, the lack of efficient tools to assess annual fruit production of the species limits the sustainable management of its resources. Therefore, production statistics are useful to organize the activities of the shea sector. This study aimed to (i) assess the interannual variation in fruit production along a climatic gradient in Burkina Faso, (ii) examine fruit production patterns according to climatic zones and tree size, (iii) assess the contribution of high-yielding trees in the annual potential production and (iv) develop allometric equations for estimating fruit yields of the species. The yield of 212 trees distributed across three climatic zones was monitored over four successive years. Within each climatic zone, fruit production was significantly different among years. Fruit production was positively and significantly correlated with tree size. The interannual variation in fruit production at tree individual level was higher in drier climatic conditions. The mean interindividual synchrony was less than 50% in each zone, suggesting a large range in fruit production patterns of the species. Annually, more than 55% of the total fruit production was supported by high-yielding trees. The best regression models for estimating fruit yields had R 2 values of 69-73% with prediction errors ranging from −7% to 4%. Our findings are useful tools for the planning of rational exploitation of shea tree's resources and its sustainable management.

Morphological diversity patterns among selected elite Shea trees (Vitellaria paradoxa C.F. Gaertn.) from Tchologo and Bagou districts in Northern Cte dIvoire

“…The impacts of climate on the expression of morphological characters have also been reported in Northern Equator (Maranz and Wiesman, 2003), Mali (Sanou et al, 2006;Tchabi and Adechi, 2014), Benin (Kougblénou et al, 2012;Kafilatou et al, 2015) and Uganda (Gwali et al, 2012). Moreover, in area of study the mineral composition of the soil, varying from one ecological zone to another, would have also influenced the expression of morphological characters as reported by Sanou et al (2006), Moore (2008) and Bondé et al (2019) respectively in studies on the vegetative characteristics of shea tree parks in Mali, Eastern Ghana and West Africa. The environmental effect significantly influencing the expression of agromorphological characters in shea tree can lead to a possible structuring of elite shea trees according to districts or departments.…”

“…To overcome these problems, progressive domestication and genetic improvement of the species are being considered. Previous research has focused on fruit production (Lamien, 2006;Aleza et al, 2018), vegetative propagation (Bonkoungou et al, 1988), molecular diversity of populations (Bouvet et al, 2004;Fontaine et al, 2004;Sanou et al, 2005;Gwali et al, 2014 ;Abdulai et al, 2016), the spatial structure of populations (Kelly et al, 2004;Sanou et al, 2006, Aleza et al, 2015, the parasitism of the shea trees (Bayala et al, 2009;Samaké et al, 2011), the variability of fruit yields (Lamien et al, 2007;Bondé et al, 2019), etc. In Côte d'Ivoire especially, researches on V. paradoxa by Salé et al (1991) reported that some characters such as fruit number, leaf and fruit size, leaf density, flowering and fruit ripening times are related to nut and butter yields.…”

Impact of environmental conditions on fruit production patterns of shea tree (Vitellaria paradoxa C.F.Gaertn) in West Africa

“…Fruit production was visually measured by counting the number of fruits on the fruiting branches. The total number of fruits per tree was assessed according to the method developed by Bondé et al (). The effect of the competition on the fruit production of shea tree was appreciated in comparison with the density of adult trees growing around each sampled tree.…”

“…Studies conducted at local scale showed that the performance in fruit production of shea tree is significantly affected by land use and soil types (Aleza, Villamor, Nyarko, Wala, & Akpagana, ; Lamien, Ouédraogo, Diallo, & Guinko, ). Previous studies in West Africa reported that climatic gradient has an effect on the species’ fruit production with the highest production in Sudanian zone (Bondé, Ouédraogo, Ouédraogo, Thiombiano, & Boussim, ; Glèle Kakaï et al, ). A significant interannual variation in fruit production of shea tree was also observed by Boffa et al (), Soro, Koffi, and Soro () and Bondé et al ().…”

“…Previous studies in West Africa reported that climatic gradient has an effect on the species’ fruit production with the highest production in Sudanian zone (Bondé, Ouédraogo, Ouédraogo, Thiombiano, & Boussim, ; Glèle Kakaï et al, ). A significant interannual variation in fruit production of shea tree was also observed by Boffa et al (), Soro, Koffi, and Soro () and Bondé et al (). However, the influence of land use and climatic conditions on interannual variation in fruit production of shea tree at individual tree and population level are poorly known.…”