Sixteen genotypes {13 promising lines and 3 check varieties i.e.Sakha 1, Sakha 3 and Giza 10} were evaluated in two successive seasons (2013/14 and 2014/15) at three locations viz: El- Gemmiza Experiment. Station., El-Garbia Governorate (clay loam), Sakha Exp. Station, Kafr El-Sheikh Governorate (clay soil) and Ismailia Exp. Station, Ismailia Governorate (sandy soil). These materials were evaluated under two plant density i.e. 1200 and 1500 seeds per m2. The experimental design was randomized complete block design with three replications for each of the twelve environments (locations x years x plant density). Data were recorded for the following characters: (1) Seed yield(ton) per fed (fed=0.42 ha), (2) Oil percentage, (3)Oil yield(kg) per fed and (4) Straw yield(ton) per fed. In addition to estimation of phenotypic and genotypic stability parameters according to Eberhart and Russell (1966) and Tai (1971) methods.The obtained results may be summarized as follows:
1- Mean squares due to environments, genotypes and genotypes × environments interactions were highly significant for seed yield per fed, oil percentage,oil yield per fed and straw yield per fed. Environment no. one (Gemmiza Station, season 2013/2014 with plant density 1200 seeds per m2) had the highest value of seed yield/fed,environment no. nine (Ismailia Station, season 2013/2014 with plant density 1200 seeds/m2) had the highest oil percentage,environment no. one (Gemmiza Station, season 2013/2014 with plant density 1200 seeds/m2) gave the highest mean for oil yield per fed and environments no. two (Gemmiza Station, season 2013/2014 with plant density 1500 seeds per m2)and no. four (Gemmiza Station, season 2014/2015 with plant density 1500 seeds per m2) gave the highest mean for straw yield per fed.
2- LinesL. 541/C/3, L. 541/D/10, L .16, L. 541/C/8 and L. 22 gave the highest seed yield/fed,linesL. 541/C/3, L. 541/D/10, L. 16, L. 22, L. 541/C/8 and L. 402/1 gave the highest oil yield/fed compared with the grand meanwhile LinesL. 541/C/3 and L. 541/D/10 gave the highest value for straw yield per fed.
3-Genotype-environment (linear) mean squares was insignificant for seedyield/fed, oil yield/fed and straw yield per fed.
4- For seed yield per fed, L. 541/C/3, L. 541/C/8, L. 541/D/10, L .16 and L .22 gave the highest mean values than grand mean, bi=1 and S2dwere not differ from zero, indicating that these lines as phenotypically stable over all environments studied theywere genotypically stable and gave the average genetic stability over all environments. These lines may be recommended to be released for commercial flax production which they performed better under all environments.With respect to oil yield per fed,lines541/C/8, 541/D/10, 402/1, L .16 and L .22 gave the minimum deviation mean square S2d, bi=1, surpassed the general grand mean and showed genotypic stability indicating that these genotypes are more stable than other genotypes, and they may recommended to be included in breeding programs for development variety of oil yield stability and or adaptability of flax. Concerning straw yield per fed, lines L. 541/D/10 and L .16 had mean values higher than grand mean, and their regression coefficient (bi) did not significantly differ from unity and deviation from regression (S2d) was insignificant. These genotypes exhibited more stability for all studied locations and considered the most desired genotypes.
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