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Performance of S 1 Alfalfa Lines from Original and Improved Populations
Author(s) -
ElNahrawy M. A.,
Bingham E. T.
Publication year - 1989
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/cropsci1989.0011183x002900040016x
Subject(s) - inbreeding depression , inbreeding , biology , selection (genetic algorithm) , medicago sativa , selfing , agronomy , botany , population , demography , artificial intelligence , sociology , computer science
Inbreeding has many uses in plant breeding. Improvement of autotetraploid alfalfa ( Medicago sativa L.) by selection during inbreeding was evaluated by measuring inbreeding depression on herbage yield in 60 S 1 lines from original and 120 S 1 lines from improved populations. Original and improved populations were produced by synthesizing both before and after selection, respectively, in ‘Vernal’, ‘Saranac’, ‘Iroquois’, ‘Honeoye’, and an experimental containing Vernal and Saranac. Selection for self‐fertility and vigor was practiced during four generations of inbreeding. Natural and directional selection during inbreeding reduced 536 S 1 lines to 152 in the S 2 , to 75 in S 3 , and to 16 in the S 4 generation. The 16 selected S 4 inbreds were used to make single crosses, and then two sets of double crosses (DCA and DCB) that were designated improved populations. The original materials were synthesized from open‐pollinated seed of 452 of the original 536 plants (W40) and by using remnant seed of 41 lines identified as superior during the inbreeding and selection process (W41). A higher proportion of plants in the improved populations produced sufficient SI seed for field testing (49%), than did plants in the original populations (27%). The S 1 lines from the improved populations showed less inbreeding depression for herbage yield (19% below S 0 ), while those from the originalshowed more inbreeding depression (28% below S 0 ). Higher percentages S 1 entries were included in the highest three herbage yield classes from improved populations (19.7%) than from original populations (12.4%). Thus, inbreeding depression was reduced in the improved populations. Selection during inbreeding to produce the 16 S 4 parents mof the improved population likely decreased the frequency of deleterious alleles and accumulated favorable alleles.