Abstract
Groundnut is an important component of the diet of both rural and urban populations in the Sub-Saharan Africa. The national average pod yield is 0.25 t/ha which is far less than the global average. The diverse environmental conditions of Zimbabwe make selection and release of stable groundnut genotypes a challenge, mainly due to genotype x environment interaction (GEI). Twenty-five groundnut genotypes were evaluated to examine the level and type of GEI on pod yield. The genotypes were evaluated under multi-environmental yield trial conducted in (2013/14 summer season) at five environments. The objectives of the experiment were to determine the presence of GEI on pod yield stability of groundnut genotypes, to identify genotypes that are specifically or widely adapted. General combined analysis of variance (GenStat Version 14) at 5% significance level indicated that genotypes (G) were not significant (p = 0.153), environments (E) and genotype x environment interactions (GEI) were highly significant (P < 0.05) on pod yield. The environment influenced yield of the groundnut genotypes. Environment and genotype explained 58.8 and 6.1% respectively of the total treatment variance, whilst the genotype by environment interaction accounted for 35.1%, indicating that environment influenced a lot on the performance of the genotypes. High significant level of GEI indicates that some genotypes may be released for specific environments. Basing on the mean pod yield value from the combined (ANOVA) analysis of variance results, groundnut genotype G24 (3.34 t/ha, check variety) was the highest yielder, followed by G7 (3.31t/ha) and then G2, G14 and G11 (3.29, 3.25 and 3.02 t/ha respectively). The results indicate that the experimental genotypes have great potential to be released and grown on large scale production. Stability analysis based on one multivariate or various uni-variate parameters to extract more information on the GEI on pod yield stability of groundnut is recommended. Key words: Groundnut, genotypes, pod-yield, multi-environmental trial, experimental, genotype x environment interaction.
Highlights
Zimbabwean environment is so diverse and so sophisticated (Nyamapfene, 1991; Rukuni et al, 2006)and that leads to very high levels of genotype x environment interactions (GEI)
General analysis of variance at 5% significance level indicated that genotypes (G) were not significant (p = 0.153), but environments (E) and genotype x environment interactions (GEI) were highly significant both (P < 0.001) on pod yield of twenty-five groundnut genotypes and accounted for 4.12, 39.68 and 23.72% of the total sum of squares, respectively (Table 3)
The results shows evidence that there was genotype x environment interaction in this study as well as significance of genotypic performance that was due to the environments
Summary
Zimbabwean environment is so diverse and so sophisticated (Nyamapfene, 1991; Rukuni et al, 2006)and that leads to very high levels of genotype x environment interactions (GEI). Higher genotype x environment interaction is usually expected to be as a result of large environmental differences as in Zimbabwe. It has been noted that genotypes tested in different locations or years often have significant fluctuation in yield due to the response of genotypes to environmental factors such as climate, soil fertility, pests and disease pathogens (Kang, 2004). These variations in yield are the ones that are usually referred to as genotype x environment interaction (GEI) and they are so frequent whenever experiments are conducted. It has been noted that a proper understanding of the environmental and genetic factors that causes the interaction as well as an assessment of their importance is likely to have a great impact on the development, evaluation and selection of superior germplasm (Magari and Kang, 1993; Basford and Cooper, 1998)
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