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 Elgin, J. H. Articles by Leath, K. T. Search for Related Content PubMed Articles by Elgin, J. H., Jr. Articles by Leath, K. T. Agricola Articles by Elgin, J. H. Articles by Leath, K. T.

Use of Strain Crosses in the Development of Multiple Pest Resistant Alfalfa with Improved Field Performance¹

Alfalfa (Medicago sativa L.) forage production is seldom limited by one pest, but by a collectinn of pests. Consequently, alfalfa cultivars need multiple pest resistance (MPR). Crossing alfalfa strains with different types of pest resistances, each with a dominant type inheritance, should result in populations with economlc levels of resistance to the combined pests. Fourteen strain cross populations were produced at Beltsville, Md. and Reno, Nev. and increased to the Syn 3 or Syn 4 generation. Evaluations of the Syn 1 to Syn 4 generations of six of the populatinns were made for resistance to anthracnose, bacterial wilt, common leafspot, rust, root-knot nematode, stem nematode, pea aphid, spotted alfalfa aphid, potato leafhopper yellowing, and for fall dormancy ratings. In addition, 3-year forage yield trials of the Syn 2 to Syn 4 of all 14 populations were conducted at Beltsville and Reno. In most cases the pest resistance and dormancy ratings of the six strain cross Populations evaluated were near the mean of the parental strains. In only a few occasions did increasing synthetic generationsignificantly reduce the level of pest resistance or dormancy levels. Forage yields of all 14 populations averaged 108% of the mean of the parent strains and 102% of the best parent. There was a trend for populations with low yielding parents to be lower yielding than populations with high yielding parents. With a few exceptions, yields remained relatively stable between the Syn 2 and Syn 4 generations. The use of strain crosses to produce MPR populations and cultlvars with improved field performance appears to be a promlsing plant breeding method for alfalfa breeders.

Key Words: Medicago sativa L. • Breeding methods • Diseases • Insects • Nematodes • Forage yields

² Research agronomist and research agronomist, USDAF, Field Crops Lab., Plant Genetics and Germplasm Inst., Beltsville Agric. Res. Ctr. (BARC), Beltsville, MD 20705; former research agronomist (presently with Pioneer Hi-Bred Int., Kerman, Calif.), and research plant pathologist, USDA, Reno, Nev.; research agronomist, USDA, Manhattan, Kans.; research geneticist and research plant pathologist, USDA, St. Paul, Minn.; research agronomist, USDA, Prosser, Wash.; and research agronomist and research plant pathologist, USDA, University Park, Pa., respectively.

Received for publication July 27, 1981.