TABLE 44.-Yield of individual F3 plants from low and high yielding strains of Marquis-Hard Federation wheat crosses, in comparison with the parents, grown at Bozeman and Havre, Mont., in 1924

Among the high-yielding strains A1-24 was first at Bozeman and B1-65 first at Havre. The latter strain also gave a high yield at Bozeman. It outyielded the higher yielding parent at both points. The mean yields and differences of this strain and the high-yielding parent at each point are as follows:

Bozeman:
B1-65-
Marquis

Difference...

Yield per plant
(grams)
6.07 ± 0.32
4. 72.21

1.35.38

The differences are both significant. The parent plant in the F2 generation yielded 11 grams and was one of those of highest yield. It appears therefore that from a high-yielding F, plant an F, strain has been obtained which gives promise of being significantly higher in yield than either parent when grown under conditions where each parent is best adapted. Other strains also have been obtained which are similarly promising.

The frequency distribution of the yields of all F, plants studied and those from duplicate parent check rows are given in Table 45, and the Bozeman data are shown graphically in Figure 9.

TABLE 45.-Yields of 2,112 F, plants of Marquis-Hard Federation wheat crosses, in comparison with the parents, grown at Bozeman and Havre, Mont., in 1924

The data show that at both stations the average yield of the hybrid plants exceeded that of the parent varieties. This accords with the Bozeman F, data. It therefore appears that transgressive segregation has occurred for higher yielding hybrid plants than those of either the Hard Federation or Marquis parents.

CRUDE-PROTEIN CONTENT

The crude-protein content of wheat is a quality factor which in recent years is receiving increasing attention and is reflected in the price of the grain when marketed. It varies with environment and yield, but in part is controlled by factors associated with variety. Lyon (12) and Roberts (15) have studied the variation and inheritance of crude-protein content within different plants and pureline strains of a variety. The present study was designed to determine how the varietal factors which determine crude-protein content are inherited in hybrids.

The crude-protein content of the grain from F2 and F3 generations and parent plants and the bulk grain from nursery rows of F, strains and parents was determined. Data on F2 plants were obtained only from Bozeman material. Because of limited quantities of grain from single plants, single determinations were made on wholewheat samples. The data are given in Table 46 and are shown graphically in Figure 11.

The crude-protein determinations were made in the research laboratory of the grain division of the Bureau of Agricultural Economics. The work was all done under the direction of D. A. Coleman, in charge of the laboratory. The writers wish to express their appreciation to the officials of the Bureau of Agricultural Economics and of the grain division of the bureau, and particularly to Doctor Coleman, for the many courtesies extended in this cooperation. The writers wish also to express their appreciation to H. C. Fellows, who with Doctor Coleman made the determinations on the F material, and to J. C. Wangler, Junior biochemist, Bureau of Plant Industry, who made the determinations of the Fs generation.

TABLE 46.-Segregation in the F, generation into frequency classes for crude-protien content of the grain of 567 F2 plants of Marquis-Hard Federation and reciprocal wheat crosses, in comparison with 189 plants of the parent varieties, grown at Bozeman, Mont., in 1923

11 12 13 14 15 16 17 18 19 20 brids and that of Hard

ent. The results from the reciprocal crosses differ by 0.12±0.04 per cent in favor of the Hard Federation-Marquis crosses. difference is statistically significant, although the difference of the

average of the reciprocal crosses from the average of the total hybrid population in each case is 0.06±0.04, indicating but little, if any, paternal influence.

The variability of the hybrids in comparison with the parents, as indicated by coefficients of variability, is as follows:

F2 hybrids.

Hard Federation..
Marquis....

Coefficient of variation

5. 108±0.102

5. 081.251

5. 398.263

The data show that the F, hybrids are slightly more variable in crude-protein content than Hard Federation and that Marquis is slightly but not significantly more variable in crude-protein

or Hard Federation.

50

content

than either the hybrids

40

SO MOCCASIN N

HF

30

20

10

In 1924, at Bozeman, Moccasin, and Havre, bulk grain from nursery rows of F, strains and parent checks from the three stations was analyzed in duplicate for crude-protein content. Grain from the poorer

yielding rows at Mocca-30

The

PERCENTAGE OF ROWS

sin was not saved.
grain from all but one
of each of the parent
check rows also was
discarded, so complete
results from that station
were not obtained. The
frequency data in half
per cent frequency clas-
ses are given in Table
47 and are shown graph-
ically in Figure 12.

Figure 12 shows that the crude-protein content increases at the stations in their order at Moccasin, Bozeman, and Havre, this being the reverse order for the stations as to yield.

9 10 11 12 13 14 15 16 17 18 19 CRUDE-PROTEIN CONTENT

FIG. 12.-Frequency distribution of F3 hybrid wheat strains and the range of variation of the Marquis and Hard Federation parent checks, together with their average crude-protein content at Moccasin, Bozeman, and Havre, Mont., in 1924

The Bozeman F, data show that the hybrids and also the Marquis parent are extremely variable. This is partly the result of soil variation. Two sections in the nursery, comprising about 15 rows each, were much lower in crude-protein content of the grain produced than the remainder of the nursery. Probably a lack of available nitrates in the soil of these two sections resulted in "yellowberry" wheat with a lower crude-protein content. At this station the F, hybrids averaged practically the same as Hard Federation in crude-protein content and 0.4 per cent less than Marquis.

TABLE 47.-Crude-protein content in the F3 generation of grain from 639 strains: of Marquis-Hard Federation wheat hybrids in comparison with 63 parent checks grown at Bozeman, Moccasin, and Havre, Mont., in 1924

At Moccasin, where the yields were slightly higher than at Boze-man, the crude-protein contents of both hybrids and parents areslightly lower. The data from a single check row of each parent shows a difference of 1.2 per cent in favor of Marquis. Considering the variability shown in the Bozeman data it is likely that the relative percentages of the two parents are not correct and that this difference between the two is greater than actually existed. The F, hybrids averaged lower than Hard Federation, which in part may be caused by the lower yielding strains having been discarded.

At Havre, where the yields were low in comparison with those from Bozeman and Moccasin, the crude-protein content was higher. The average of the hybrids was nearly intermediate to that of the parents. at this point, which is similar to the F2 results at Bozeman.

The data on the crude-protein content of the grain of F2 plants afforded opportunity to select for high crude-protein content in that generation. Some of the F, plants of highest crude protein were the parents of families studied on a plant basis in the F, generation. Data for some of the F, strains of highest and lowest average crudeprotein content, compared with the nearest check rows of the parents studied in the same manner, are given in Table 48.