FACTORS FOR YIELD AND QUALITY OF SPRING WHEAT 
47 
Differences in the competitive ability of normal and dwarf plants 
may introduce a variable into the data for average plant yield, but 
it seems doubtful whether this variable had any very pronounced 
effect on the result. Average plant-yield data are given in Table 43. 
Table 43. — Yield per plant in the F 3 generation of 523 Marquis-Hard Federation 
wheat hybrids, in comparison with 61 parent checks grown in nursery rows at 
Bozeman and Havre, Mont., in 1924 
Number of rows 
Yield per plant 
Bozeman 
Havre 
• 
F 3 
hybrids 
Hard 
Federa- 
tion 
Marquis 
F 3 
hybrids 
Hard 
Federa- 
tion 
Marquis 
0. 5 gram 
3 
197 
69 
23 
7 
3 
1. 5 grams 
12 
3 
1 
2 
8 
2. 5 grams.- .. . 
4 
36 
81 
56 
36 
10 
1 
6 
3. 5 grams -- ... 
6 
5 
2 
I 
4 
3 
4. 5 grams --- 
6. 5 grams 
7. 5 grams 

8. 5 grams - - 
9. 5 grams 
Total.. 
Average yield in grams 
224 
5.03 
13 
4.19 
13 
4.96 
299 
1.94 
18 
2.11 
17 
1.68 
The plant data from Bozeman show that the hybrids averaged 
slightly more in yield than Marquis, the higher yielding parent. At 
Havre the hybrids were intermediate in yield, averaging less than 
Hard Federation, the higher yielding parent. Under the unfavorable 
droughty conditions prevailing at Havre the Hard Federation checks 
consistently outyielded the Marquis checks in 1924, while at Boze- 
man under favorable conditions the Marquis checks outyielded those 
of Hard Federation. 
The F 3 yield data from Bozeman were affected by the premature 
ripening of some plants, due to root-rot. The Marquis parent was 
less affected by this disease than the hybrids or Hard Federation. 
The percentage of Marquis plants prematurely ripened was 13.6, 
that of Hard Federation 18.7, and that of the F 3 hybrids 18.0. There 
was considerable variation among the hybrid rows as to the extent 
of injury. Only one row, however, was not affected, the greatest 
amount of injury being 38 per cent. The F 3 hybrid material offered 
an opportunity to select both for resistance to the root-rot and for 
high yield. 
Selections were made in the F 2 generation on a plant-yield basis. 
Some of the highest yielding F 2 plants were included among the 
families studied on the individual-plant basis in the F 3 generation. 
The highest and lowest yielding of the F 3 families, compared with 
the nearest labeled parent check rows, are given in Table 44. 
Strain A3-90 was the lowest yielding of 25 strains at Bozeman and 
Bl-78 the lowest of 16 strains at Havre. As an average for both 
points, strain B2-98 ranked lowest, although it outyielded Marquis, 
the lower yielding parent at Havre. No one strain had a yield sig- 
nificantly less than that of the lowest yielding parent at either of 
the two stations. 
