Document Type : Original research
10.12816/ejpb.2019.256168
Abstract
This study was conducted at the Agricultural Extension Field, El-Gemmeiza, El-Gharbiah Governorate, Egypt during the two successive growing seasons 2014/15 and 2015/16. The eight common wheat cultivars (Triticum aestivum L. em Thell), Line 1, Sids 1, Sids 13, Shandweel 1, Misr 1, Sakha 61, Sakha 94 and Gemmeiza 12 were crossed in a half dilele cross design to estimate combining ability associated with grain yield and its component in three expirements under the three sowing dates, i.e. of 25 October (D1 sowing date), 15th November (D2 sowing date), 5th December (D3 sowing date) and to determined the most stable parents and crosses with high grain yield. Also, to determine the pest method of selection will be used in the segregation generations. The results showed that mean squares due to sowing dates were highly significant for all traits studied, indicating as expected that the differences between the three sowing dates were markedly differed. Mean squares due to genotypes, parents, crosses, parent vs. crosses and interactions between parents or crosses with sowing dates were highly significant for all yield, and some of its components at the three sowing dates as well as their combined analysis. Mean squares due to GCA, SCA, GCA x sowing date and SCA x sowing date were highly significant and/or significant for grain yield and some of its components in the three sowing dates and combined analysis. The ratios of GCA / SCA that exceeded the unity were detected for yield and yield components traits at the three sowing dates and their combined analysis, indicating that the largest part of the total genetic variability associated with these traits is a result of additive and additive x additive gene action. While, for other traits, the non-additive gene effects seemed to be responsible for their inheritance. It could be concluded that the breeder can be used the four parents P5 (Misr 1), P6 (Sakha 94), P7 (Sakha 61) and P8 (Gemmeiza 12) to improve yield and earliness including them in breeding programs. The breeder could include the five crosses (Gemmeiza 12 x Line 1), (Sakha 94 x Sids 1), (Gemmeiza 12 x Shandaweel 1), (Sakha 94 x Misr 1) and (Sakha 61 x Sakha 94) in breeding programs to segregate lines with high grain and straw yield, since they shwoed significant and positive (Ŝij) effects for grain and straw yield and some of its components in the three sowing dates and their combined analysis. Finally, pedigree method of selection will be an excellent method for breeders to select good lines with high yield and stability under a wide range of sowing dates based on yield and yield component traits.
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