STUDIES ON THE INHERITANCE OF EARLINESS IN 
WHEAT 1 
By Victor H. Florell 3 
Agronomist, Office of Cereal Investigations, Bureau of Plant Industry 
INTRODUCTION 
The studies reported in this paper 
were undertaken primarily to deter¬ 
mine the inheritance of earliness in 
wheat in connection with breeding for 
earlier varieties. As the cross under 
observation was intended purely for 
economic purposes, only general notes 
were taken on the Fi progeny. But in 
regard to the F 2 and F 3 progenies, earli¬ 
ness notes were taken on individual 
plants and families. 
The investigation of the problem of 
early maturity in plants has engaged 
for many years the active interest of 
geneticists and plant breeders. The 
value of such investigation has been 
emphasized by the practical import¬ 
ance of developing varieties of crop 
plants suitable for the early market or 
of such precocity as to escape unfavor¬ 
able conditions induced by climate or 
crop pests. 
In general, the behavior of the hybrid 
material in the different studies re¬ 
ported has been similar. In the Fi 
progeny, time of heading or maturity 
has been found to be intermediate 
between that of the parents, with the 
means or the hybrid inclining toward 
one or the other parent.. In the F* 
the tendency has been for the inter¬ 
mediate condition to be maintained 
but with a range of variation almost 
covering the extremes of both parents, 
and both with and without the group¬ 
ing into classes showing definite segre¬ 
gation. In subsequent generations the 
segregation into distinct classes be¬ 
comes more and more marked as homo¬ 
zygosity is approached. 
REVIEW OF LITERATURE ON 
INHERITANCE OF EARLINESS 
EXPERIMENTS WITH WHEAT 
William Farrer (6 ) 3 early observed 
that the progeny in the Fi generation 
was intermediate between the parents, 
and that there was no difference in this 
respect in the reciprocal of a cross. In 
the F 2 he found rather wide variation 
in time of ripening. 
Biffen (2) found that the Fi produced 
ripe grains well along toward the date 
of ripening of the late parent of an 
interspecific cross between an early 
(Polish) and a late (Rivet) wheat. In 
the F 2 , although all plants flowered 
simultaneously, many plants ripened 
at the same time as the early parent, 
while some were almost ripe and still 
others green. He concluded that earli¬ 
ness is dominant. 
Fruwirth (8, p. 176, 288, 814) be¬ 
lieves the early ripening to be partially 
dominant in wheat, rye, and barley. 
Thompson (15) made numerous 
crosses between eight varieties of 
wheat, ranging from very early to late 
maturing. In ten Fi crosses with the 
late parent the ripening period of most 
plants was near the mean of the late 
parent. In the F 2 most individuals 
were intermediate, with no indication 
of “heaping up” except in the inter¬ 
mediate position, but the range of 
variation extends nearly from that of 
the earliest to that of the latest of the 
parent varieties. He found, as did 
Biffen (2), that earliness and lateness 
are inherited independently of other 
characters. He also made the inter¬ 
esting observation that the earliest 
plants of an F 2 population frequently 
were quite as large and productive as 
the latest grandparent. 
Freeman (7) made crosses between 
durum and common white wheats, 
as well as between two common wheats. 
He found that the average date of first 
heading in both F 2 and F 3 progenies in 
every case was intermediate but nearer 
to that of the late parent. In the 
durum cross, there was an extension 
of range much beyond that of the late 
parent. 
1 Received for publication Mar. 1, 1924—issued January, 1925. 
2 The writer wishes to express appreciation to Dr. E. B. Babcock, Dr. R. E. Clausen, and Prof. C. M. 
Titus, of the University of California, for the kindly advice and assistance given during the course of this 
investigation. 
3 Reference is made by number (italic) to “Literature cited,” p. 347. 
Journal of Agricultural Research, 
Washington, D. C. 
( 333 ) 
Vol. XXIX, No. 7 
Oct. 1, 1924 
Key No. G-437 
