Evaluation of Performance of Introduced Yam Bean (Pachyrhizus spp.) in Three Agro-Ecological Zones of Rwanda

Ndirigwe Jean,Kamarirwa Vestine,Rubaihayo Patrick,Tumwegamire Silver,Rukundo Placide,Mwanga O M Robert,Tukamuhabwa Phenihas,Agaba Rolland,Kayinamura Evrard,Wolfgang J Grüneberg

doi:10.1007/s12042-017-9188-5

Abstract

The yam bean (Pachyrizhus spp) was recently introduced as a root crop with high-yield potential, considerable protein and micro-nutrient concentration to investigate its potential for food production in Rwanda. Except for Chuin types (Pachyrizhus tuberosus) which have high storage root dry matter (RDM) (26 to 36%), most accessions are consumed raw and are reported to have low RDM. The present study aimed to evaluate and identify adapted high yielding yam bean accessions in major agro-ecological zones of Rwanda. Field experiments with 22 accessions were conducted in 2012 at three research sites representing the major agro-ecologies of Rwanda. Strict reproductive pruning was followed to enhance fresh storage root yields. Across locations, ANOVA indicated highly significant differences (p < 0.01) for genotypes (G), locations (L), seasons (S) and G x L effects for storage root yield, vine yield and harvest index and accounted for 21.88%, 43.41%, 1.43% and 13.25% of the treatment sum of squares, respectively. The GGE bi-plot revealed that EC209018 is high yielding but unstable. However, genotypes, AC209034, AC209035 and EC209046, were outstanding in terms of adaptation and relative stability across the 3 locations, suggesting consistent root yields irrespective of location and environmental conditions. The GGE scatter plot showed that all genotypes formed one mega-environment for storage root yield (Karama, Musanze and Rubona) and two mega-environments for biomass yield (Karama and Rubona as one mega-environment and Musanze the second one). This study revealed that Karama is the most suitable environment for evaluation and selection of yam bean for yield components in Rwanda.

Highlights

Yam bean (Pachyrhizus spp.,) is a small genus of storage root forming legumes with neo-tropical origin
This study revealed that Karama is the most suitable environment for evaluation and selection of yam bean for yield components in Rwanda
This paper focused on the results of storage root yield, genetic variability for yield and yield components, as well as GxE interactions for yam bean accessions introduced to Rwanda

Summary

Introduction

Yam bean (Pachyrhizus spp.,) is a small genus of storage root forming legumes with neo-tropical origin. The genus Pachyrhizus belongs to the subtribe Glycininae (Lackey 1977) and the closest major crop is soybean (Glycine max). The genus consists of five species (Sørensen 1990; Doyle and Doyle 1993) and three of these species are cultivated including; the Andean yam bean (P. ahipa), Mexican yam bean. (P. erosus), and Amazonian yam bean (P. tuberosus) (Sørensen 1996). Whereas other legume crops such as soybean and common bean (Phaseolus vulgaris) are grown mainly for their edible seeds, yam bean is grown mainly for its edible storage roots (Sørensen et al 1997). The yam bean produces seeds but are not edible because they contain high amounts of toxic polyphenols especially rotenoids. The extract of rotenoids has potential for use in insecticide products to control thrips, aphids and whitefly larvae in crop production (Lautié et al 2013; Noman et al 2007; Alavez-Solano et al 1996)

Methods

Results

Conclusion