MORPHO-MOLECULAR CHARACTERISTICS AND PHYSICO-CHEMICAL PROPERTIES OF BALANITES AEGYPTIACA (L.) DELILE IN THE SAHELIAN ZONE OF NIGERIA

Abstract

Balanites aegyptiaca (BURKAN) is a wild fruit tree of high ethnomedicinal importance in the Sahelian zone of Nigeria for treating ailments like typhoid and malaria. The wild populations of the species are threatened by overexploitation and habitat loss. Variation in plant leaf, fruit morphology, genetic diversity, and physico-chemical properties from different locations which are essential for superior trait selection and vital to developing strategies for its domestication and conservation, is limited in Nigeria. This study was therefore conducted to determine the fruit and leaf morphology, physico-chemical and molecular characteristics of Balanites aegyptiaca in the Sahelian zone of Nigeria. Eight locations in five states: Baure and Mashi (Katsina), Buratai (Borno), Dumsai and Gashua (Yobe), Gamawa (Bauchi), Guri and Kirikasama (Jigawa) were purposively selected, based on the availability of Balanites aegyptiaca trees. Ten mature trees were randomly selected from each location. Thirty ripe fruits and leaves were randomly collected from each tree. Fruit Length (FL, cm), Fruit Weight (FW, g), Fruit Thickness (FT, cm), and Pulp Weight (PW, g) were determined. Leaf morphology: Leaf Length (LL, cm), Leaf Width (LW, cm), and Leaf Thickness (LT, cm) were measured. Oil was extracted from the fruit kernels obtained from each location using soxhlet extraction method. Physico-chemical properties of extracted oil: refractive index, viscosity (cP), acid, and iodine values (mgKOH/g) were analysed. Genetic characteristics of selected trees were determined using chloroplast gene sequences of matK region. Nucleotide diversity (Pi), Parsimony informatics sites (Ps), Polymorphic sites (S), and average number of nucleotide difference (k) were determined following standard procedures. Data were analysed using descriptive statistics, cluster analysis, and ANOVA at α0.05. The FL varied significantly from 2.45±0.31 (Dumsai) to 3.08±0.26 (Kirikasama), while FW ranged from 1.77±0.19 (Gashua) to 2.13±0.16 (Baure). Baure had the highest FT (1.84±0.39), while Guri had the least, (1.41±0.15). The PW significantly decreased from 4.44±1.87 (Gamawa) to 2.18±1.33 (Buratai). The LL, LW, and LT significantly increased from 0.41±0.05 (Dumsai) to 0.62±0.35 (Baure); 0.21±0.13 (Buratai) to 0.44±0.19 (Baure); and 0.41±0.05 (Dumsai) to 0.62±0.35 (Baure), respectively. This supported the feasibility of location as a criterion for selection in trait improvement. Refractive index and viscosity increased from 1.36±0.15 (Mashi) to 1.48±0.06 (Gamawa) and 41.33±2.08 (Gashua) to 48.67±2.52 (Buratai), respectively. Acid and iodine values varied significantly from 1.36±0.07 (Dumsai) to 2.11±0.07 (Baure) and 67.07±1.53 (Gamawa) to 85.33±2.52 (Baure), respectively. The Pi and Ps varied from 0.002 (Dumsai) to 0.264 (Mashi) and 0.00 (Dumsai) to 2.00 (Mashi), respectively. The S and k ranged from 3.0 (Dumsai) to 302.00 (Mashi) and 2.00 (Dumsai) to 151.70 (Mashi), respectively. The high genetic diversity in Mashi signified germplasm potential for species improvement. Species population in Baure and Mashi formed a distinct cluster with the highest bootstrap value (100), while the other populations formed a single cluster with bootstrap value of 4. The genetically diverse population in Mashi is a potential source for superior germplasm required for the domestication and improvement of Balanites aegyptiaca and could play vital roles in germplasm collection.