نوع مقاله : مقاله پژوهشی
نویسندگان
گروه اصلاح نباتات، دانشکده علوم زراعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction: Tobacco (Nicotiana tabacum L.) is one of the most important plants of Solanaceae family and is mainly consumed in the tobacco industry due to the commercial use of leaves. The production of hybrid varieties is one of the most important breeding programs for plants including tobacco. Estimation of genetic parameters is one of the most important stages of breeding programs for hybridization that helps in better selection of genotypes. This study was conducted with the aim of estimating general, private combinability, heterosis and genetic variance components for agronomic and morphological traits in tobacco genotypes through line × tester analysis.
Materials and Methods: In this study, 16 sterile F1 hybrids with 8 parents, namely 4 lines and 4 testers, along with two controls (K326 and TC100), were studied in a Randomized Complete Block Design (RCBD) with a total of 26 treatments and 3 replications in the field of Tirtash Tobacco Research and Education Center. The agronomic and morphological traits studied included leaf length and width (centimeters), number of leaves, plant height (centimeters), stem diameter (millimeters), chlorophyll index, number of days to flowering, leaf area coefficient, and leaf shape index. SAS software and Line × Tester program were used to perform all statistical calculations.
Results: The results of the analysis of variance of the data for all morphological and agronomic traits studied showed that the effects of treatments for the traits plant height, chlorophyll index and number of days to flowering were statistically significant at the probability level of one percent and for the trait leaf number at the probability level of five percent. Then, for the traits in which the effects of treatments were significant, the Line × Tester analysis test was performed. Based on the results of the Line × Tester analysis of variance, the significance of the parental effect, the effect of crossing and the interaction of parents × crossings for all the traits studied indicates the existence of sufficient genetic diversity between the parental cultivars and their crosses and significant heterosis for all the traits studied. The examination of the relative contribution of lines, testers and the interaction of line × tester to the total variance showed that for all the traits studied, the contribution of the interaction of line × tester to the total variance was greater than the contribution of lines and testers to the total variance.
Conclusion: The results indicate the existence of genetic diversity among genotypes. Based on the results of general parental combinability, the Coker 371G line and the Cocker176 tester (CMS) had positive and significant general combinability, and these lines and testers can be used as parents in tobacco breeding programs. Based on the results of private combinability, the K394 × MN 944 (CMS) hybrid, due to its positive and significant private combinability in terms of chlorophyll index, and the NC60 × Coker 374 (CMS) hybrid, due to its positive and significant private combinability in terms of plant height and positive heterosis percentage, can be used for the production of male sterile hybrid tobacco. The results of the estimation of genetic variance components showed that in the traits of leaf number, plant height and number of days to flowering, incremental variance plays a major role and the selection method from among segregating generations is appropriate. While the chlorophyll index trait was mostly affected by non-additive variance, hybrid production is recommended to improve this trait.
کلیدواژهها [English]