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Parental Inbreeding and Performance of Alfalfa Single‐crosses 1
Author(s) -
Hill R. R.
Publication year - 1975
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1975.0011183x001500030027x
Subject(s) - diallel cross , biology , inbreeding , inbreeding depression , cultivar , horticulture , genetics , combinatorics , mathematics , hybrid , population , demography , sociology
S 2 and S 4 progenies were obtained from 10 S 0 parents each from ‘MSA‐W4’ and ‘MSB‐W4’ alfalfa ( Medicago sativa L.). Two five‐parent diallel sets were attempted within S 0 , S 2 , and S 4 parental generations in each cultivar. All but one of the sets with S 2 and S 4 parents gave incomplete diallels. First harvest dry matter yields were measured in small row plots during each of two growing seasons. Average yields of the S 2 −crosses were less than those of the S 0 −crosses in all sets. Individual exceptions to the average trend occurred in both populations, but more frequently in MSA‐W4 than in MSB‐W4. The number of S 4 −crosses was small, and the results with them were variable. Yields of all S 4 crosses in one set, which had one parent common to all crosses, were greater than yields of the corresponding S 0 or S 2 −crosses. Other S 4 crosses generally yielded less than the corresponding S 0 or S 2 −crosses. Mean squares for both general (GCA) and specific combinnig ability (SCA) pooled over sets in MSA‐W4 increased from the S 0 to the S 2 parental generation. This increase was greater for SCA than for GCA. GCA was significant in the S 2 −crosses from MSB‐W4, but no combining ability mean square was significant in the S 2 or S 4 −crosses from MSB‐W4.