Abstract
Sweet potato [Ipomoea batatas) (L.) Lam] is grown by small holder farmers across a wide range of environments in Malawi. A multi-location trial of eight genotypes for three seasons at six research stations was undertaken using additive main effects and multiplicative interaction (AMMI) model analysis to determine the genotypes’ stability and influence of genotype × environment interactions (GEI) on storage root yield. ANOVA showed high significant differences in storage root yield of the genotypes among seasons and locations (p≤0.01). Genotype, environment and genotype × environmental interaction significantly influenced storage root yield variation of the cultivars (p≤0.01). The variance in yield was mainly attributable to environment variability (62.86%) than genotypes variation (14.25%) and G × E interactions (15.06%). Semusa was superior for storage root yield (27.77t/ha) and Lu96/334 was the most inferior (11.19 t/ha). AMMI stability analysis revealed that LU96/303 (24.72 t/ha) was the most stable genotype across sites. Biplot analysis showed that Chitedze and Baka were sites conducive for high yields hence can be used for preliminary yield evaluation to capture maximum genotypes’ yield potential, while Lunyangwa was the lowest yields site; therefore useful for assessing the potential of worst performance of genotypes under unfavourable environmental conditions. Key words: G × E interactions, multi-locational trial, stability, sweet potato, genotypes, root yield.
Highlights
A better understanding of genotypes and environment interactions (GEI) is critical for any crop varieties improvement program (Singh et al, 2006; Osiru et al., 2009; Andrade et al, 2016) as it helps breeders to identify superior genotypes and their best environments (Yan and Rajcan, 2002; Thiyagu et al, 2013)
Sweet potato [Ipomoea batatas) (L.) Lam], like other crops suffers yield losses that are due to abiotic and biotics limitations (Tekalign, 2007; Kivuva et al, 2014; Chalwe et al, 2017) an understanding of the nature and magnitude of GEI among sweet potato genotypes is essential in both sweet potato breeding and variety release (Singh et al, 2006; Rukundo et al, 2013)
Genotypic yield levels have been the focus of many sweet potato farmers but adaptation to environments and stability of the genotypes have always been the underpinning determinants of final yields (Eberhart and Russell, 1966; Bilbro and Ray, 1976; Rea and Vieira, 2002)
Summary
A better understanding of genotypes and environment interactions (GEI) is critical for any crop varieties improvement program (Singh et al, 2006; Osiru et al., 2009; Andrade et al, 2016) as it helps breeders to identify superior genotypes and their best environments (Yan and Rajcan, 2002; Thiyagu et al, 2013). Sweet potato [Ipomoea batatas) (L.) Lam], like other crops suffers yield losses that are due to abiotic and biotics limitations (Tekalign, 2007; Kivuva et al, 2014; Chalwe et al, 2017) an understanding of the nature and magnitude of GEI among sweet potato genotypes is essential in both sweet potato breeding and variety release (Singh et al, 2006; Rukundo et al, 2013). This study used the additive main effect and multiplicative interaction (AMMI) model to assess elite sweet potato genotypes in Malawi to determine their stability and influence of genotype × environment interactions (GEI) on storage root yield in order to identify superior cultivars
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