552 



INDEX 



Ustilago maydis, 24 



Variability, 49 



Variance components, estimating, 368 



Variance components, genetic interpreta- 

 tions, 503 



Variances of general, maternal, and specific 



effects, estimation of, 368-69 

 Variety crossing, 16 



Variety testing, 426 



Vascular organization, 108 



Vegetative propagation, 12, 13 



Viability, 335 



Vigor 



hypotheses for difference in, 300-302 

 loss of and selling, 13 

 reestablished by outcrossing, 7 



Vigor in original plant as measure of number 

 of favorable yield genes, 428 



Vigorous hybrid and weak inbred, difference 

 between, 327 



Virulence, 279 



Water requirements of hybrids, 106 

 Waxy gene, 239 



Weak inbred and vigorous hybrid, differ- 

 ence between, 327 



White dent corn, 32 



frequency curve of grain rows, 21 

 White dent maize, 29 



average grain-row numbers, 38 



average values in the families of, 35 



yields per acre, 38 



Xenia, 8, 9 

 history of, 10 

 in maize, 10 



X-ray dosage and mutation frequency, 

 271-74 



Yeast genetics, 257 



Yeast, advantages for biochemical genetics, 



257 



Yield loss from one generation to the next, 

 42 



Yield of seed, prediction of, 302 



Yielding abilitv, correlations indicative of, 

 54 



Zea {See Maize) 



Zea mays 



double crosses, 378 



gamete selection for specific combining 

 ability, 378-88 



single cross performance data, 378 



test crosses, 379 

 Zygote, 371 



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