GENE EFFECTS FOR YIELD AND YIELD COMPONENTS IN TWO SOYBEAN CROSSES UNDER NORMAL AND DEFFICIT IRRIGATIONS

doi:10.12816/ejpb.2019.256697

GENE EFFECTS FOR YIELD AND YIELD COMPONENTS IN TWO SOYBEAN CROSSES UNDER NORMAL AND DEFFICIT IRRIGATIONS

Document Type : Original research

10.12816/ejpb.2019.256697

Abstract

The present study was conducted at the experimental farm of Itay EL-Baroud Agricultural Research Station, ARC during the summer season of 2017 and 2018 to determine the gene effects, heritability in broad and narrow sense and genetic advance % by using the five populations (P₁, P₂, F₁, F₂ and F₃) of the two crosses namely; Giza 21 x Line 164 and DR101-937 x Line 164. For this purpose the two crosses were grown in two experiments under normal irrigation (full number of irrigations) and reduced irrigation (half number of irrigations); each experiment was arranged in randomized complete block design with three replicates. The results showed that, mean squares due to of the two segregating generations F₂ and F₃ were higher than mean squares of non-segregating generations (P₁, P₂ and F₁₎ under normal and reduced irrigation for both crosses. Reduced irrigation had negative effects on seed yield and its components in the five populations of the cross Giza 21 x Line 164 where the reduced irrigation led to increasing number of empty pods/plant and decreasing number of pods/plant. Also, seed yield of P₁, P₂, F₁, F₂ and F₃ were sharply decreased under reduced irrigation. While, yield and its components of the cross DR101-937 x Giza 21 were not affected by reduced irrigation in all populations, except number of pods and seed yield of P₂; these traits sharply decreased under reduced irrigation. The C and D scaling test for all traits in the two crosses Giza 21 x Line 164 and DR101-937 x Giza 21 showed that at least one or both of C or D were found significant in normal and reduced irrigation, indicating the presence of non-allelic interaction in the inheritance of all studied traits. In both crosses, the additive gene action (d) and epistasis gene action from the type additive x additive (i) were significant for most yield traits under normal and reduced irrigations. Finally, the significance of dominance gene (h) was absent in all traits under both irrigation treatments. The desirable shape of epistasis (complementary) was presented in most traits in both crosses. The genetic advance (∆ G) of Giza 21 x Line 164 ranged from 1.66% in plant height to 12.99% in main root length under normal irrigation and ranged from 1.42% in 100-seed weight to 12.71% in seed yield/plant under reduced irrigation. The cross DR101-937 x Line 164 exceeded the cross Giza 21 x Line 164 in genetic advance% in most trait, where ∆G % of DR101-937 x Line 164 ranged from 3.32% for 100-seed weight to 17.03% for seed yield/plant under normal irrigation and ranged from 1.39% for 100-seed weight to 21.85% for seed yield/plant under reduced irrigation. From the previous results it could be clear that pedigree selection in the early segregation generations could be an excellent method of these crosses for the breeder view to select line of high genetic stability for most studied traits especially seed yield.

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