مطالعه نوع اثرات ژنی و برآورد روابط همبستگی بین صفات مورفولوژیکی و تحمل به بیماری سیاهک معمولی (Ustilago maydis) ذرت (Zae mays L.)

 Aim and Background. Since chemical control of corn common smut disease to be unsuccessful (that its agent is Ustilago maydis), screening of resistance hybrids to smut disease is necessary for maize breeding.  Materials and Methods. In this study, 89 single crosses hybrids including 60 single crosses derived from hybridization of 20 S6 inbred lines as female parents and 3 S6 commercial elit testers (K18,K19,K1264/5-1) as male parent and 29 new hybrids were evaluated in a RCBD with 2 replications in Agriculture and Natural Resources Center of Khorasan Razavi Province in 2008. The measured traits were leaf no. above ear, total leaf no., plant height, ear height, anthesis and silking date, anthesis silking-interval(ASI), spore injection time, leaf and stulk disease, ear length, ear diameter, row no./ ear, kernel no./ row, physiological maturity, infected plant percentage, tassel disease percentage, percentage and severity of smut traits, grain hector liter weight and moisture. Results. The ANOVA showed significant differences among test crosses in leaf no. above ear, total leaf no., plant height, ear height, anthesis and silking date, anthesis silking-interval(ASI), spore injection time, stem and leaf disease, ear length, ear diameter, row no./ear, kernel no./row, physiological maturity (p<0.01), and leaf and stem disease (p<0.05). the correlation analysis showed significant positive relations between grain moisture and smut infection percentage (0.68 **) and diseases severity (0.63**), but we observed negative significant relation between grain hectoliter weight with deasease severity (-0.65**) and smut infection percentage (-0.69**). Conclusions. Also, Line×tester analysis for related traits of smut resistance showed significant variance for infected stem and leaf and infected plant no. that for these traits only additivity gene effect were significant.