Proximate and Mineral Nutrition of Common Bean Genotypes as Influenced by Harvesting Time

Onkgolotse G Moatshe-Mashiqa,Patrick K Mashiqa,Odireleng O Molosiwa

doi:10.5539/jas.v14n1p85

Abstract

Common bean is the most consumed legume by humans and hence significant for global food security and nutritive value mainly iron (Fe) and zinc (Zn). The objective of the study was to evaluate the effect of harvesting time and genotypes on proximate and mineral composition of common bean. Two field experiments were carried out in Sebele (24o33&prime;S, 25o54&prime;E, 994 m above sea level) horticultural fields during summer 2018/2019. Treatments included two common bean genotypes DAB 564 (white) or 520 (red) and three harvesting stages as the early, mid and late season harvest. In both seasons, genotype and harvesting time significantly (P &lt; 0.05) influenced proximate, macro and micro mineral composition of common bean seeds. Generally genotypes studied had a sufficient amount of proximate and mineral content with crude protein, iron (Fe) and zinc (Zn) content as the most abundant minerals at a range between 20-22%, 33-101 mg g-1 and 41-45 mg g-1, respectively across harvesting times. Genotype DAB 564 (white coloured) significantly (P &lt; 0.05) produced seeds with the highest concentration of proximate and mineral contents especially zinc (45 mg g-1) and iron (70 mg g-1) content irrespective of season. Harvesting common bean seed early or mid-stage produced high seed concentration of proximate, micro and macro mineral content across genotype or season.

Highlights

Legumes are staple food in human diets around the world (FAOSTAT, 2010; Ndidi et al, 2014), their wide cultivation in most countries with total world production rates of more than 17 million tonnes, led by China, Indonesia, India and Turkey as the largest producers and consumers of beans (FAOSTAT, 2010; Richardson, 2012)
Crude fibre and protein resulted with 17 or 41% and 6 or 7% genotypic difference, respectively during season 1 or 2 (Table 1), indicating genetic variations with genotype DAB 564 expressing a better nutrition than DAB 520
Proximate and mineral nutrition of common bean is significantly influenced by genotype and harvesting time

Summary

Introduction

Legumes are staple food in human diets around the world (FAOSTAT, 2010; Ndidi et al, 2014), their wide cultivation in most countries with total world production rates of more than 17 million tonnes, led by China, Indonesia, India and Turkey as the largest producers and consumers of beans (FAOSTAT, 2010; Richardson, 2012). Maruapula and Novakofski (2010) has reported iron as the only micronutrient with the intake above the recommended two-thirds of recommended daily allowance (RDA) above making common beans a vital source of iron. Despite the nutritional value of legumes including common bean, most African countries including Botswana still experience high incidences of food insecurity, hunger and micronutrient induced malnutrition including zinc and iron deficiencies (Nestel et al, 2006). The adult age groups of men and women has poor health conditions which are mostly caused by low macro and micro nutrient intake especially protein, fiber, iron and zinc (Maruapula & Novakofski, 2010).

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