Abstract
Stability of yield and its attributes were assessed for nineteen genotypes over twelve environments (two seasons 2009 and 2010 × six planting dates), to determine the quantitative responses of cowpea genotypes. The interaction between genotypes and environments (G×E) were significant for all the characters studied characters except pod length, hundred seed weight and weight of pods per plant. The longest pods and heaviest hundred seeds weight were produced by genotype TVU 21, IT82C-116, providing the highest number of seeds per plant. Whereas, Sudany genotypes gave the highest number of pods per plant and heaviest seeds per plant, Blackeye Crowder genotypes had the heaviest pods per plant and total dry seed yield. The best season and planting date are fall season, third planting date (August, 15th) for most studied traits. The stable genotypes were Chinese Red, IT81D1064, IT85F2205 and Sudany for total dry seed yield. Key words: Sowing dates, stability parameters, genotype × environment, selection, grain yield.
Highlights
Cowpea (Vigna unguiculata (L.) Walp) is one of the most ancient crops known to man
Stable performance of cowpea genotypes across contrasting environments is essential for the successful selection of stable and high yielding varieties (Dashiell et al, 1994; Ariyo, 2000; Ahmed et al, 2005; Yousaf and Sarwar, 2008)
The occurrence of large genotype × environment (G × E) interaction affects the recommendations of the breeders in selecting genotypes for specific environment
Summary
In Egypt, cowpea is a popular vegetable crop. Stable performance of cowpea genotypes across contrasting environments is essential for the successful selection of stable and high yielding varieties (Dashiell et al, 1994; Ariyo, 2000; Ahmed et al, 2005; Yousaf and Sarwar, 2008). Combination of genotypes stability with high yield is an important criteria for selecting high yielding and stable genotypes. The regression technique (Eberhart and Russell, 1966) has been used In this technique, the response of genotypes to a given environment is considered. Environment analysis is used to provide unbiased estimates of yield and other agronomic characteristics and to determine yield stability or the ability to withstand both predictable and unpredictable environmental variation (Kamdi, 2001).
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