FACTORS FOR YIELD AND QUALITY OF SPRING WHEAT 
61 
relation was slightly negative. The correlation between F 2 plants 
at Bozeman in 1923 and F 3 strains produced therefrom at Havre in 
1924 was positive but small and not significant. The average cor- 
relation of 0.132 can not be considered very important. 
The ripening period and the fruiting period are very strongly cor- 
related, as shown by all of the four coefficients obtained. The 
average correlation of 0.758 is larger than between any other pair 
of characters and due to their dependence in chances of occurrence. 
The F 2 data at Bozeman illustrate how dependent each factor is on 
the other and are given in Table 56. 
Table 56. — Correlation between heading period and fruiting period in F2 plants of 
Marquis-Hard Federation wheat crosses grown at Bozeman, Mont., in 1928 
Ripening period (days) 
Fruiting period 
August 
September 
Total 
25 
27 
29 
31 
2 
4 
6 
8 10 
36 davs 
1 
8 
13 
8 
1 
38 days . 
1 
9 
13 
41 
17 
2 
5 . 
31 
36 
21 j 
1 
32 
8 
14 
23 
10 
1 
3 
19 
69 
90 
38 
1 
1 
7" 
15 
29 
7 
92 
2 
2 
10 
16 
11 
88 
124 
48 davs 
3 
2 
2 ' '"{' 
1 
128 
86 
22 
1 
Total 
30 
73 
93 
56 222 59 
41 
8 1 
583 
/=0.817±0.009. 
The ripening period also is positively correlated with height, the 
later strains being the taller. Significant correlations were obtained in 
four instances, and the average correlation of 0.276 is fairly important. 
A longer ripening period also was found to be positively correlated 
with larger yield. Under the widely different Montana conditions 
significant positive correlations were obtained in all four experi- 
ments, and the average correlation of 0.343 is important. 
The ripening period and crude-protein content are on the average 
slightly negatively correlated. This relationship was obtained in 
two of four instances. In 1923 at Bozeman the F 2 results probably 
are the most typical of average conditions with, a correlation coeffi- 
cient of -0.148 ±0.028. In 1924 at Bozeman two bad spots in the 
nursery, owing probably to a lack of available nitrates, resulted in 
earlier maturity of about 30 rows and "yellow-berry" kernels. This 
increased an otherwise positive correlation about twice the amount it 
might have been. At Moccasin in 1924 the correlation was practi- 
cally zero. At Havre, however, under severe drought conditions 
the important negative correlation of — 0.378± 0.034 was obtained. 
This illustrates the differences which are frequently obtained be- 
cause of the lack of a proper balance between soil moisture and avail- 
able nitrates. 
