Peter Nelson

Date of Award:


Document Type:


Degree Name:

Master of Arts (MA)


Plants, Soils, and Climate


George Stewart


The results presented in this paper are from data accumulated by a study of the F3 generation of a cross between the two varieties, Sevier and New Zealand wheat. This cross was made during the summer of 1920 by Professor George Stewart with the object of combining the high-yielding power of Sevier with the strong straw of New Zealand. In the fall of 1922 the problem was assigned to me, at which time I selected about 150 superior plants, possessing the desired characteristics, at least so far as appearance was concerned. Since then these plants and the F3 generation have been studied mainly with the object of finding out whether size characters behave in Mendelian fashion or not. Other characters received attention incidentally, and will also be reported briefly.

To study a variable problem with any degree of accuracy there must of necessity be a definite means by which variations may be measured. Size differences in straw are extremely difficult of measurement, and measurements at best can only be approximations. It was decided, therefore, to make a careful study of size variations in wheat heads, and only estimate straw strength.

The study of this problem is valuable for two main reasons:

1. If high-yielding power and straw strength can be combined from two different varieties it is worth knowing because of the economic value of such a combination. From this point of view the original object of the cross under discussion itself justifies the investigation.

2. Since it is not a definitely settled question as to whether heritable size fluctuations behave according to the principles of Mendelism the problem has both interest and value from the point of view of genetics.