Seven sugar beet cultivars (Three poly germ Sara / 2135, Dina / 2134 and Bts /302 and four mono germ genotypes i.e. Helios poly, Marathon, Ravel and Francesca) were evaluated in two successive seasons (2014/15 and 2015/16) in three different planting date using randomized complete block design with 3 replications for each of the six environments at Moshtohor Experiment research station, EL-Khalubiah. Data were recorded for root yield (ton)/ fad. and sugar yield (ton)/ fad. Estimation of phenotypic and genotypic stability parameters were made according to Eberhart and Russell (1966) and Tai (1971) methods. The obtained results may be summarized as follows:
Mean squares due to environments, genotypes and genotypes × environments interactions were highly significant for the tow studied traits. The genotype Heliospoly gave higher value of root yield, followed by Ravel and then Francesca, while the other genotypes gave the lowest mean root yields across environments. Also, the mention genotypes give high sugar productivity/ fad.
The wide range of the regression coefficient (bi) ranged were found for seven sugar beet genotypes indicating different response to environmental conditions. The genotypes of Bts/302, Marathon, Ravel and Francesca were classified as highly adapted to a wide range of planting date environments and two out of the previous stable genotypes represented in Ravel and Francesca, exhibited higher root yields, so, these ones considered preferred.
The genotype Francesca had mean values higher than grand mean, and their (bi) did not significantly differ from unity and (S2d) was insignificant and very low. This genotype exhibited more stability for all studied environments and considered the most desired genotypes. Meanwhile, Genotypes Bts/302 and Heliospoly had a degree of above average stability (α < 0) and (λ = 1) with probability 80%. These genotypes may be recommended to be released for commercial sugar production which they performed better under all environments.
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