F 
A COMPARISON OF MAIZE-BREEDING METHODS 5 
The interannual parent-offspring correlation of rank for the six 
seasons was as follows: 
Correlation of Correlation of 
Year rank! Year rank ! 
(ib) be 0.41+0.16 1971-222 2S 0.87+0.06 
P1920 5221 f64-, 10 1 7g ar 18+ .20 
Li | So ae 06+ .15 : 12a, 24. =~ 380+ .20 
All correlations are positive in sign, and for the early years the 
coefficients are significant. 
PLANTS FROM HIGH-YIELDING ROWS COMPARED WITH HIGH-YIELD. 
ING PLANTS SELECTED WITHOUT REGARD TO THE PROGENY 
PERFORMANCE 
In each year’s experiments one half of the progenies represented 
selections from the highest performing progenies of the preceding 
year. The other half represented selections from high-yielding indi- 
viduals without regard to the behavior of the progeny in which 
they occurred. 
Table 2 shows that, in the crossed blocks, over a period of six years 
there was no significant difference between the progenies descended 
from high-yielding progenies and those descended from high-yielding 
plants. In four of the six years the “high-row”’ progenies outyielded 
the “high-plant’’ progenies, but in no single year is the difference 
ees and in the total for the six years the yields are practically 
equal. 
TaBLE 2.—Mean length of ears of maize progenies descended from high-yielding 
progenies and from high-yielding individuals 
| _ Crossed block (cm.) Selfed block (cm.) | 
e2. e ___| Selfed as 
Wear | | | percent- 
: : : | age of 
bocce Pen | rotale ee? | See. | regal) ecommee 
i | | | 
ba, SP es EA UES a ee a RR 
Awe is oy St Sai aa 25.5 22.7 | 2410) 20.2 19.2 | 197 | 81.7 
TS ae 37.86 | 42.23) 40.04, 36.22, 28.34 2. 28 80.6 
ae souet ee 25.77| 25.15} 25.46| 2270| 19.7 21.2 83.3 
| | Siageee ris a? aL 34.19| 3242! 33.31) 29.10) 25.35| 27.23 81.7 
| ENS De gaan | 30.55} 31.14| 30.84) 29.23| 23.47 26. 35 | 85.4 
| ei eo | 31.00] 29.90; 30.45) 27.10} 2260! 24.85 81.6 
— — — 
ee Sie | 30.81 | 30.60; 30.70| 27.43) 23.11 25.27 82.3 
| i | 
In the selfed blocks, on the contrary, the high-row blocks out- 
yield the high-plant blocks in all of the six years. The mean differ- 
ence is 4.48+0.57 per cent, a departure from zero of 7.9 times the 
probable error. 
The comparisons are based on small plantings, and the yields 
vary from year to year. The effects of annual fluctuations are 
eliminated by confining the comparisons to the differences instead of 
the absolute yields. That the small size of the blocks does not 
Vitiate the results is indicated by the regularity of the results. This 
eecarty is most apparent in the percentage difference between the 
selfed and crossed blocks. In the six years the maximum range of 
6z d?2 
1Calculated by Spearman’s formula e=1-N(N?-))’ where d=difference in rank and N=number. 
ee EE 
