# Diversity in Selected Grain Mineral and Protein among Pigeonpea Landraces
## 4 Discussion  
The genotypic variability observed for the various minerals including Ca, Cu, Mg, Mn, P and Zn indicated the potential for exploiting the landraces in pigeonpea genetic improvement programs that are aimed at the optimization of the grain of such minerals. Similar findings of genetic variation in nutritional characteristics were previously reported in improved and vegetable pigeonpea varieties [22; 23]. In a similar study involving common bean, differences in individual minerals and protein were attributed to fertilizer applications and edaphic factors [24]. For instance, the grain content of Zn and Ca was due to soil and/or foliar applications of chemical fertilizers containing these minerals [25; 26]. Nonetheless, the pigeonpea genotypes in this study were grown without the use of fertilizers. In the current study, genotype 'G-03' attained the highest concentrations for most mineral elements, thus demonstrating its superiority and potential for exploitation in future pigeonpea programs for enhancing grain nutrients. The grain mineral elements in these pigeon landraces are essential for the optimal functioning of the immune system [23; 27]. For example, calcium is important for normal heartbeat and muscle functioning, bone health as well as neurotransmission [28]. The highest Ca content observed in genotype 'G-03' (2103.43 mg/kg) was double that in similar studies [29]. Moreover, the Ca content which was observed in this study for 'G-03' was higher than in common bean [24]. The high levels (>15,000 mg/kg) of K accumulated by pigeonpea landraces such as 'G-13', 'G-06' and 'G-09' in this study also suggested the potential to reduce the risk of cardiovascular diseases and diabetes when included in the diet [30]. The presence of K in the body is also associated with an increase in iron utilization and hypertension control [31]. In comparison with other leguminous species, the P content in the pigeonpea landraces was higher than in both lentil (_Lens culinaris_) (299.45 mg/100 g) and garden pea (_Pisum sativum_) (352.79 mg/100 g). On the other hand, the Mg content observed in this study was almost two-fold that observed in a similar study in Nigeria (84.31 mg/100 g), suggesting that the accumulation of this mineral depends on both genetic and environmental factors since distinct genotypes were used in the studies [32]. Mg acts as a cofactor for more than 300 enzymes, thus regulating multiple fundamental functions such as glycaemic control, type 2 diabetes, myocardial contractions and osteoporosis [33; 34]. Among the micronutrients in this study, iron was the most abundant microelement (ranging between 32.99 and 66.05 mg/kg), and was similar to the content observed in chick \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Cluster** & **Sub-Cluster** & **Number of Genotypes** & **Total** & **Genotypes** & **Type** \\ \hline \multirow{4}{*}{I} & \multirow{4}{*}{a} & \multirow{4}{*}{2} & \multirow{4}{*}{5} & G-01 & Exotic \\ \cline{3-6}  & & & G-08 & Local \\ \cline{3-6}  & & & G-11 & Exotic \\ \cline{3-6}  & & & G-12 & Exotic \\ \cline{3-6}  & & & G-02 & Exotic \\ \hline \multirow{4}{*}{II} & \multirow{4}{*}{a} & \multirow{4}{*}{3} & \multirow{4}{*}{4} & G-06 & Exotic \\ \cline{3-6}  & & & G-10 & Improved \\ \cline{3-6}  & & & G-13 & Exotic \\ \cline{3-6}  & & & G-09 & Exotic \\ \hline \multirow{4}{*}{III} & \multirow{4}{*}{a} & \multirow{4}{*}{2} & \multirow{4}{*}{5} & G-03 & Local \\ \cline{3-6}  & & & G-14 & Exotic \\ \cline{3-6}  & & & G-04 & Exotic \\ \cline{3-6}  & & & G-05 & Local \\ \cline{3-6}  & & & G-07 & Exotic \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Groups of pigeonpea landraces determined via cluster analysis based on grain mineral and protein content. pea (48.6-55.6 mg/kg), but was significantly lower than in lentil (75.6-100 mg/kg) [35; 36]. The landraces 'G-11' and 'G-13', which showed relatively high grain Fe content, could be used in biofortification aimed at fighting anaemia in vulnerable groups such as women and children.