Morphological and nutritional composition of Bauhinia thonningii pods and seeds in Northern Ethiopia

Wild edible fruits are rich in micronutrients and serve as an essential source of nutrition for the poor in developing countries, where malnutrition is widespread. The morphological and nutritional compositions of Bauhinia thonningii pod and seed were evaluated using samples collected from two distinct agroecological zones, the warm moist lowlands (WMLL) and tepid sub-moist mid-highlands (TSMMHL), in the Tselemti district, Ethiopia. Data were analyzed using independent sample t-test, ANOVA with a general linear model, and Principal component analysis (PCA) for morphological traits, proximate composition, and mineral content to determine their association with agroecological zones. The results showed that morphological traits such as the mean pod length (p < 0.000), pod width (p = 0.036), pod thickness (p = 0.005), pericarp weight (p = 0.006), total seed weight (p = 0.003), individual seed weight (p = 0.005), and number of seeds per pod (p < 0.000) differed significantly between the two agroecological zones (p < 0.05). Higher mean values of pod length (18.34 cm), width (2.87 cm), thickness (0.85 cm), total pod weight (11.56 g), total seed weight (8.93 g), and number of seeds per pod (51 ns) were recorded in the warm moist lowlands compared to the tepid sub-moist mid-highlands. The moisture content of the B. thonningii pod (9.02%) and seed (7.02%) was higher in tepid sub-moist mid-highlands than in the warm moist lowlands. The crude protein (9.74 and 30.73%), crude fat (0.96 and 2.48%), crude fiber (26.03 and 32.86%), total carbohydrates (56.30 and 33.70%), and energy values (1106.36 and 1103.87 kJ/100 g) of the pod and seed, respectively, were higher in the WMLL compared to the TSMMHL. All proximate compositions of the B. thonningii pod and seed varied significantly between the two agroecological zones (p < 0.05), except for ash content. Most mineral concentrations in the pod and seeds, such as calcium (152.26 and 36.77 mg/100 g), magnesium (129.59 and 8.04 mg/100 g), potassium (1325.44 and 130.61 mg/100 g), and sodium (8.99 and 16.90 mg/100 g), were significantly higher in the warm moist lowland agroecology. This may be attributed to higher humidity, soil mineralization, evaporative concentration, and increased soil nutrient movement under warm lowland environmental conditions. Significant differences were observed in the concentrations of all minerals in the pods and seeds between the agroecologies, except for magnesium and zinc in the seed analysis. Overall, the findings indicate that understanding the morphological, proximate, and mineral compositions of B. thonningii is valuable for its sustainable utilization, conservation, domestication, and breeding. The pods and seeds of B. thonningii possess high nutritional potential and could be used for both human and animal nutrition following further detailed investigation.