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-Gharbia 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) Straw yield(ton) per fed (fed=0.42 ha), (2) Long fiber percentage, (3) Long fiber yield(ton) per fed and (4) Seed 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 forstraw yield per fed, long fiber percentage, long fiberyield per fed and seed yield per fed. The 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, environment no. ten (Ismailia Station, season 2013/2014 with plant density 1500 seeds per m2)had the highest long fiber percentage, environment no. four (Gemmiza Station, season 2014/2015 with plant density 1500 seeds per m2) gave the highest mean for long fiber yield per fed and environment no. one (GemmizaStation, season 2013/2014 with plant density 1200 seeds per m2)had the highest value of seed yield/fed.
2- LinesL. 541/C/3 and L. 541/D/10 gave the highest value for straw yield per fed, long fiber yield per fed and seed yield per fed. While the two check varieties Sakha 3 and Giza 10 had the highest long fiber percentage but they gave the lowest seed yield per fed.
3- Genotype-environment (linear) mean squares was insignificantfor straw yield per fed, long fiber percentage and seed yield per fed.
4- For straw yield per fed,linesL. 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.With respect to fiber yield per fed,linesL. 541/C/6, L. 402/1 and L .16 gave the minimum deviation mean square S2d and these strains had surpassed the general grand mean, indicating that these genotypes are more stable than other genotypes, while six genotypes i.e.L. 541/C/6, L. 541/D/8, L. 541/D/10, L. 402/1, L .16 and the check variety Sakha 3 showed genotypic stability so it may recommended to be included in breeding programs for development variety of fiber yield stability and or adaptability of flax. Regarding 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 they were 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.
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