نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری، گروه ژنتیک و بهنژادی گیاهی، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران
2 دانشیار، گروه مهندسی تولید و ژنتیک گیاهی، واحد شوشتر، دانشگاه آزاد اسلامی، شوشتر، ایران
3 استادیار پژوهش، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی صفیآباد، سازمان تحقیقات، آموزش و ترویج کشاورزی، دزفول، ایران
4 استادیار، گروه مهندسی تولید و ژنتیک گیاهی، واحد شوشتر، دانشگاه آزاد اسلامی، شوشتر، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction
Heat stress is a serious threat to food security and agricultural production. Stress tolerance indices are one of the most widly used methods for selecting stress tolerant genotypes among researchers. Furthermore, the diallel crosses method has also been introduced as one of the desirable genetic designs for selecting suitable parental lines and genotypes to obtain superior hybrids. Evaluating genotypes for combining ability in early generations is an essential step in producing desirable hybrids. The aim of this study was to estimate stress tolerance indices as well as the general combining ability (GCA) and specific combining ability (SCA) of genotypes in order to determine superior heat stress tolerant lines and hybrids.
Materials and methods
The plant materials of this experiment were six lines and 15 hybrids resulting from their one-way diallele crosses (21 treatments) that were evaluated in two independent experiments, including early (July 15, heat stress conditions) and recommended (August 15, non-stress conditions) sowing dates in a randomized complete block design with three replications. The experiment was carried out at the Safiabad Agricultural Research and Education Center, Dezful, Khuzestan province, Iran, in the summer of 2019. The measured traits in this study included number of days to maturity, grain yield and yield components. To assess heat tolerance in the studied lines and hybrids, stress tolerance and sensitivity indices and principal component analysis (PCA) were used. GCA of lines and SCA of hybrids were also estimated based on grain yield and yield components under non-stress and heat stress conditions using the first model of the second method of Griffing. All statistical and genetic analyses were performed using Minitab version 16 and Diallel-SAS softwares.
Research findings
The results showed that five indices including mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), harmonic mean (HA) and tolerance index (TOL) had a positive and significant correlation with grain yield in both normal and heat stress conditions. Therefore, these indices are introduced as the best indices for selecting heat-tolerant genotypes. Considering the results of these indices as well as the results of principal component analysis and biplot diagram, three lines C3-95-3, C3-95-9 and C3-95-10, and three hybrids C3-95-3×C3-95-9,
C3-95-3×C3-95-10 and C3-95-9×C3-95-10 were identified as heat tolerant genotypes. The effects of SCA for grain yield, days to maturity, number of rows and number of grains per row in two hybrids C3-95-3×C3-95-9 and C3-95-3×C3-95-10 under both non-stress and heat stress conditions were positive and significant. According to the results of this experiment, the three parental lines C3-95-10, C3-95-9 and C3-95-3, in addition to being tolerant to heat stress and better performance than other lines under heat stress conditions, had the ability to transfer these characteristics to hybrids.
Conclusion
The results of this study showed that stress indices can be effectively used to screen heat-tolerant genotypes. The selected lines can be used as potential sources for production of heat tolerant genotypes in breeding programs. Considering the significant effects of SCA for grain yield, number of grains per row and number of days to maturity, and the low GCA/SCA ratio, the role of non-additive effects of genes in controlling these traits was more important than additive effects. Since the cross superiority due to low breeding value can not be reliable in the selection process, therefore, heterosis due to non-additive and dominance effects of genes can be used to control the relevant traits and hope to produce suitable hybrids.
کلیدواژهها [English]
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