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

This Article Full Text (PDF) A correction has been published A correction has been published A correction has been published 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 Yen, S.-T. Articles by Murphy, R. P. Search for Related Content PubMed Articles by Yen, S.-T. Articles by Murphy, R. P. Agricola Articles by Yen, S.-T. Articles by Murphy, R. P.

Cytology and Breeding of Hexaploid Alfalfa. I. Stability of Chromosome Number¹

Two hexaploid amphiploids (2n=6x=48), a naturally occurring hexaploid, and two hexaploid wild species of alfalfa (Medicago spp.) were used in this study. The parents, F₁ hybrids, and a portion of their progenies were analyzed cytologically. Variation in somatic chromosome number was detected in most of the populations studied. Chromosome numbers varied from 2n=36 to 2n=51 with a mean of 46.7 ± 2.51 in the F₁ population, and from 2n=33 to 2n=51 (except for one with 2n=72) with a mean of 46.1 ± 2.34 in the selfed and crossed progenies derived from euplold F₁ plants (2n=48). The percentage of hexaploids was estimated at 64 in the F₁ population and 27 in the selfed and crossed progenies of the euploid F₁ plants.

A wide range in plant vigor among individual plants was observed in the field nurseries about 2 months after transplanting. The overall mean vigor score (I lowest to l0 highest) was 5.9 for the progenies of hexaploid F₁ plants and 5.6 for the progemes of aneuploid F₁ plants. Both values were significantly lower than the mean vigor of the cultivated check cultivars (2n=-4x=32). The frequency of plants with vigor of 7 (average of the check cultivars) or higher within the progenies of hexaploid and aneuploid F₁ plants was 38 and 28%, respectively. No apparent relationship was detected between vigor and the chromosome number of the plants. In the progenies of hexaploid F₁ plants, 33% of the plants with vigor of 7 or higher were hexaploids.

Key Words: Amphiploid • Euploid • Aneuploid • Medicago sativa • M. caerulea • M. falcata • M. cancellata • M. saxatilis

² Research associate and professor, Cornell Univ., Ithaca.

Received for publication September 29, 1978.