Author
Milligan, Scott | |
Comstock, Jack |
Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only Publication Acceptance Date: 5/1/2006 Publication Date: 7/1/2006 Citation: Milligan, S.B., Comstock, J.C. 2006. Inheritance of resistance to ratoon stunting disease and implications for selectin in florida. [abstract]. American Society of Sugar Cane Technologists. 26:52 Interpretive Summary:
Technical Abstract: Ratoon Stunting Disease (RSD) (caused by Leifsonia xyli subsp. xyli (Davis et al.) Evtushenko et al.) may impart major economic yield losses in sugarcane, particularly in ratoon crops. Although control may be obtained by mechanical sanitation and the use of disease-free seed-cane, genetic resistance would add to its control. The germplasm from the sugarcane breeding program based at Canal Point, FL has been evaluated for RSD susceptibility since 1993. Susceptibility to RSD was determined by a serological test specific to RSD. The number of colonized vascular bundles per imprint (CVB) was determined from inoculated tests of Stage 2 and Stage 3 genotypes from the Canal Point breeding program. Stage 2 yields and RSD evaluations are determined from independent, unreplicated tests with about 1500 genotypes. Stage 3 trails consist of replicated tests of about 130 clones at four locations while an independent RSD inoculation test of the germplasm is conducted using a replicated test. We estimated narrow-sense heritabilities of log transformed CVB and yield components using a half-sib parental analysis. The narrow-sense heritability percent for CVB was low (h2 = 7.8%) but similar to that estimated for stalk number and sugar yield. Non-additive genetic variance was not indicated. Within test clonal repeatability analysis of the Stage 3 material indicated that the clonal repeatability was about 0.50 while Spearman correlations of Stage 2 CVB with Stage 3 CVB averaged r = 0.21. This suggested that the within test estimate is significantly inflated by the genotype x year variance. Correlations of CVB with the yield components of germplasm in the Stage 2 and Stage 3 trials indicated very low (r <0.10) to no correlation with any yield component. Among the inoculation tests, the check cultivars often varied as did their responses within the tests, however they tended to fall into three categories: resistant (CVB near 0), moderately susceptible (5 |