In order to investigate the phenotypic for quality characteristecs of bread wheat in relation to kernel protein content and the effects of this environmental affected trait on exoression of genotypic effects of bread wheat cultivars for high molecular weight glutenin subunits(HMWG)this study was conducted, To obtaindifferent levels of kernel protein content in four cultivars of wheat, 5levels of nitrogen fertilizer (0,45,90,135 and 180 kg/ha N)were applied in a factorial experiment(4×5)within a RCBD of 3 replication. The HMWG genotypes of the cultivars were determined by SDS-PAGE . The quality characters: protein cintent, farinofraphic components (Water absorption, dough development and stability duration,dough weakening rate and valorimetery valre)T Zeleny and SDS sedimentation volume and finally kernel hardiness were determined for investigated vultivars.Then using ANOVA and mean comparison as well as correlation analyses , follow up of characters as the phenotypic factors of protein cintent and the HMWG genotypes of the cultivars were assayed. Results indicated that by applying of different levels of nitrogen, in two three times in the stages of tillering to kernel development, the mean protein content increased from 11.4 to 13.4% . investigation of phevotypic performance of quality characters in different genitypes for HMWG subunits ( the good and poor genotypes according to genome score for gluten strength and bread making quality) in different levels of protein content showed that the response of quality characters will be different in different varieties . in this study nikmesjad as a good qrality cultivar holding alleles encoding subunits 2* and 5+10 for GIU-A1 and GIU-D1 respectilvely showed less response to increase in protein content over 12% and its potential for glrten strength was expressed in this amount of protein content, while M-70-4 as a poor cultivar for gluten strength and genome score, showed a good response to increasing of protein content and its quality characteristecs like SDS sedimentation volume, valorimetery value and dough development time got better. Finally it appears that the cultivars with poor gluten strength express their genotypic potential for bread making quality in protein content of over 12% and approzimately 13% while the cultivars with good strength of gluten appear to express their genitypic potential for quality in approzimately 12% protein content.
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