HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Miller, P. R. Articles by Christie, B. R. Search for Related Content PubMed Articles by Miller, P. R. Articles by Christie, B. R. Agricola Articles by Miller, P. R. Articles by Christie, B. R.

Genetics of Resistance to Verticillium Witl in ‘Vertus’ Alfalfa

Dep. of Agronomy and Plant Genetics, Univ. of Minnesota, St. Paul, MN, 55108
Agric. Canada, Res. Stn., P.O. Box 1210, Charlottetown, PE, Canada, C1A 7M8.

^* Corresponding author.

It is difficult to bread alfalfa (Medicago sativa L.) cultivars with >50% resistance to Verticillium albo-atrum Reinke & Berthier. The objectives of this study wre to determine if selecion for resistance to V. albo-atrum within the alfalfa cultivar Vertus reduces general combining ability (GCA) compared to specific combining ability (SCA) and to compare disease evaluation in a controlled environment based on foliar symptoms and stem colonization. Two populations of Vertus were studied, one selected on the absence of foliar symptoms after repeated inoculation, the other selected at random. Correlations between stem colonization and foliar symptoms in both populations were low. Seedling height, stem colonization, and first and second-regrowth foliar symptoms were analyzed for GCA and SCA. Estimates of GCA variances for these characters were three to five times greater in the random population than in the resistant population. Estimates of SCA variances were similar for both populations, with one exception. Estimated GCA/SCA ratios were 4.7:1 and 5.0:1 for foliar symptom evaluation of two regrowth periods in the random population. Corresponding estimated GCA/SCA ratios in the resistant population were 2.9:1 and 1.9:1 This suggests that additive genetic variance will provide limited improvement of resistance levels and nonadditive genetic variance will not be a source of higher levels of resistance to verticillium wilt in this cultivar.

Received for publication October 15, 1990.