Genotype by Environment Interaction on Resistance to Cassava Green Mite Associated Traits and Effects on Yield Performance of Cassava Genotypes in Nigeria.

Joseph Onyeka,Essie Blay,Eric Danquah,Chiedozie Egesi,Isaac Asante,Lydia Jiwuba,Agyemang Danquah

doi:10.3389/fpls.2020.572200

Abstract

Cassava is the main source of carbohydrate for over 70% of the people in Nigeria, the world’s largest producer and consumer of the crop. The yields of cassava are, however, relatively low in Nigeria largely due to pests and disease infections that significantly lead to inconsistencies in productivity of cassava genotypes in various environments. Fifty-eight F1 hybrid cassava genotypes plus their two parents which served as check varieties were evaluated in three locations for two years (that is six environments). The objectives of the study were to evaluate genotype by environment interactions (GEI) on resistance to cassava green mite [CGM, Mononychellus tanajoa (Bondar)] associated traits and effects on yield performance of cassava genotypes in Nigeria and to identify superior genotypes that exhibit high stability which combine CGM resistance and high fresh root yield with general and specific environmental adaptation using additive main effects and multiplicative interaction (AMMI) and genotype stability index (GSI). The combined analysis of variance based on AMMI revealed significant genotype, environment, and genotype by environment interactions (GEI) for all traits. The percentage variation due to environment was higher than the percentage variation due to genotype for cassava green mite severity (CGMS), leaf retention (LR), root dry matter content (RDMC), and fresh root yield (FRY) indicating that environment greatly influenced the expression of these traits. The percentage variation due to GEI accounted for higher percentage variation than that of genotype and environment separately for all traits, indicating the influence of genotype by environment interaction on expression of the traits. These findings reveal that screening/evaluating for these traits needs multi-environment trials. According to GSI ranking, genotypes G31 (IBA131794), G19 (IBA131762), the check variety G52 (TMEB778), and G11 (IBA131748) were identified as the most stable and most resistant to CGM which also combine high FRY and other useful agronomic traits, implying that these traits in cassava can even be incorporated as preferred by farmers. These genotypes can be tested in more environments to determine their adaptability and potential recommendation for release to farmers for growing.

Highlights

Cassava (Manihot esculenta) is a perennial vegetatively propagated woody shrub, mostly grown as an annual that belongs to the Euphorbiaceae family
The main aim of this research was to analyze the effects of genotype by environment interaction on resistance to cassava green mite (CGM), shoot morphological and yield traits on 60 cassava genotypes using AMMI model
fresh root yield (FRY) had a significant positive correlation with SG (r = 0.31), RDMC (r = 0.32), and biomass (r = 0.28). These results indicate that plants with severe CGM had glabrous to little leaf pubescent, poor leaf retention and stay green, low root dry matter content, low root and stem yield

Summary

Introduction

Cassava (Manihot esculenta) is a perennial vegetatively propagated woody shrub, mostly grown as an annual that belongs to the Euphorbiaceae family. It is commonly grown in the tropical regions of the world (El-Sharkawy, 2003) with Nigeria being the world’s largest producer with approximately 45 million tonnes (Adekanye et al, 2013). Cassava is cultivated nearly in all the agro-ecological zones of Nigeria for its edible parts (roots and leaves). This provides farmers with steady income since it can be harvested at regular intervals

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