Search

The genotype + genotype x environment (GGE) biplot methodology has the potential to determine combining ability effects, identify efficient testers, and distinct heterotic groups in a line x tester study. However, it has not been adequately applied for such analysis. Therefore, this study was done to assess the combining ability of some maize inbred lines and testers for grain yield, identify most efficient testers and classify inbred lines into heterotic groups using GGE biplot. Fifteen experimental single cross hybrids, generated from a 5 x 3 line by line x tester crosses procedure, were evaluated across seven sites in Iran in 2018 using a randomized complete block design with three replicates per entry at each site. According to the pooled analysis of variance, crosses showed significant differences for grain yield. Also, the differences observed among the testers, inbred lines, and interactions for the line x tester, crosses x environments, line x tester x environment was significant. The inbred line L4 was recognized as outstanding for its general combining ability (GCA) effect and the tester K18 was highly efficient based on its discriminating power. It can be concluded that the crosses of L4 x K47/3 and L4 x B73 are suggested to release high grain yield hybrids. Results of the GGE biplot analyses were close to the conventional line x tester method in combining ability and heterotic patterns of the yield of lines, grouping, and identification of testers. [ABSTRACT FROM AUTHOR]

A thermomechanical processing (TMP) method consisting of annealing, cold working, and partial remelting was employed to modify the microstructure and mechanical properties of Al 2024 alloy. The effects of the semi-solid temperature and holding time at the semi-solid temperature on the microstructure of the alloy were studied. The results showed that the optimum parameters were 610 °C and 7 min. Also, T6 heat treatment was applied to the thermomechanical processed alloy with the best combination of the parameters to examine its effect on the characteristics of the alloy. The results revealed that the amounts of yield strength and ultimate tensile strength increased, but T6 heat treatment did not have any remarkable effect on the tensile properties of the thermomechanical processed sample but improved the hardness of the alloy. In addition, the fracture mode in the thermomechanical processed sample was ductile while in the sample that underwent T6, brittle fracture was dominant.