K. Iwaki et al., Adaptation and ecological differentiation in wheat with special reference to geographical variation of growth habit and Vrn genotype, PLANT BREED, 120(2), 2001, pp. 107-114
Geographical variation of growth habit was studied for 749 landraces from v
arious parts of the world, with special reference to their adaptation and e
cogeographical differentiation. The total frequency of spring-type landrace
s was 49.9%, and varied between localities. Spring-type landraces were freq
uent in two distinct areas where the average January temperature was either
below -7 degreesC or above 4 degreesC, with winter-type landraces in areas
from -7 degreesC to 4 degreesC. These results indicated that geographical
Variation of growth habit is closely related to the degree of winter coldne
ss. An analysis of the Vrn genotype for 216 spring-type landraces demonstra
ted the uneven distribution of four Vrn genes, with Vrn4 being the least fr
equent. The adaptive Vrn genotype was different between localities. Genotyp
es carrying Vrn-A1 and additional Vrn gene(s) were frequent in two distinct
areas where the average January temperature was either below -7 degreesC o
r over 10 degreesC, while genotypes with any of three Vrn genes, except Vrn
-A1, adapted to areas with temperatures from 4 degreesC to 10 degreesC. The
refore, it was concluded that the adaptability of wheat landraces differed
depending on their growth habit and Vrn genotype, and that ecotypes with di
fferent Vrn genotypes were allopatrically distributed as a result of adapta
tion to different winter temperature. However, the differential distributio
n of Vrn-B1, Vrn-D1 and Vrn4 could not be explained by their adaptability,
and might. reflect the polyphyletic origin of common wheat.