Genotypes with insignificant GEI are considered to be stable [8]

Genotypes with insignificant GEI are considered to be stable [8]. Stability analysis methods are divided into two main groups: univariate and multivariate [9]. Among multivariate methods, the additive main effects and multiplicative interaction (AMMI) analysis is widely used for GEI assessment. This method has been shown to be effective because it captures

a large portion of the GEI sum of squares [6]. It clearly separates main and interaction effects depending on their statistical significance and presents plant breeders with different kinds of selection opportunities, and the model often provides meaningful interpretation of agronomic data [7]. The AMMI analysis is useful in informing important decisions in breeding programmes, such as which genotypes exhibit specific adaptation and the selection of testing environments [6]. This is particularly

important for new breeding programmes that have not yet optimised their respective genotype testing networks. The results of an AMMI analysis are often presented in a biplot, which displays both the genotype and environment values and their relationships using the singular vector technique [7]. Such information, especially on GEI and associated stability, is important this website in selecting early-yielding cassava genotypes with improved adaptation to the abiotic stresses that prevail in target environments [10] and [11]. Selection of early-yielding cassava genotypes has become important in the national cassava breeding programmes in Africa as a result of increasing demand for such genotypes by

farmers [10], [12] and [13]. They are considered to be important in situations where mounting pressure on land for urban and industrial development compels farmers to intensify production, and in semi-arid regions, where early-yielding genotypes can be harvested after only one cycle Epothilone B (EPO906, Patupilone) of rain [12]. Wholey and Cock [14] have proposed that one way of improving the efficiency of cassava production in terms of fresh storage root yield (FSRY) per unit time is by selecting early-yielding genotypes with shortened growth periods. Previous research has shown that early-yielding cassava genotypes are harvested at ≤ 12 months after planting (MAP) [10], [12] and [15]. For the purpose of this study the performance and stability of the genotypes were evaluated for FSRY, defined as early FSRY, and related traits at 9 MAP. In that context, this study was conducted to assess the effect of genotype, environment and GEI on early FSRY and related traits and also to identify stable genotypes for early FSRY and related traits. Trials were conducted at three diverse locations in Uganda: at Namulonge and Jinja National Agricultural Research Institutes and at Nakasongola on private farmland. Namulonge is located at 32°36′ E and 0°31′47″ N, 1134 meters above sea level (m.a.s.l.); Jinja is located at 33°11′ E and 0°27′ N, 1173 m.a.s.l.

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