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Genetic Changes in Oat Bulk Populations under Winter Survival Stress 1
Author(s) -
Marshall H. G.
Publication year - 1976
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/cropsci1976.0011183x001600010003x
Subject(s) - biology , juvenile , avena , habit , population , resistance (ecology) , horticulture , zoology , botany , agronomy , ecology , demography , psychology , sociology , psychotherapist
Convergent crossing was used to produce 58 different winter oat ( Avena by zantina K. Koch and A. sativa L.) bulk populations, and these populations were subjected to 4 years of winter survival stress in Pennsylvania. Two types of observations were subsequently made to determine the effect of natural selection on these populations. First, all populations were compared in the F 8 and F7 generations to determine performance for juvenile growth habit, freezing resistance in a laboratory test, and winter survival in the field. Second, F 8 and F7 individual plants were isolated from 12 populations and classified for juvenile growth habit, maturity, and plant height. Derived F 1 and F 8 lines from six of these populations were compared for freezing resistance. Thirty‐four of the 58 populations increased significantly in freezing resistance and changed similarly for winter survival in the field. The majority of the populations that changed greatly for these chadracteristics were low performers in the F 3 . Initially elite populations made small, nonsignificant changes under natural selection. Nonresponsiveness to natural selection in the latter populations did not reflect low genetic variability, since a wide range in freezing resistance was observed among derived lines, regardless of generation or population. In every population, the F 3 growth habit ranged from intermediate to very erect. By the F 7 generation, 28 populations were significantly more decumbent in juvenile growth habit. Plants from 10 out of 12 populations were significantly more decumbent by the F 7 generation; and all populations were later in maturity. Plants with decumbent juvenile growth were latest in maturity, and these two characteristics were correlated within each generation of all populations. Five of 12 populations were taller by the F 7 generation, and the others did not change in average plant height under natural selection. Changes in maturity and plant height were independent of natural selection on winterhardiness. If the bulk population approach is to be used for natural selection for winterhardiness, controlled selection pressure during one or more early generations may have to be applied so that the tendency to increase gone frequencies for lateness and tallness can be offset.