Two extensively inbred strains of summer squash – designated “crookneck” and “scallop” – are crossed. The length of fruit in the crookneck averages 40 cm and that in the scallop averages 7 cm. In the F1 generation of the cross crookneck X scallop, the average fruit length was 18 cm and the variance in fruit length was 11 cm2. In the F2 generation obtained from the cross
F1 X F1 and grown under the same conditions, the variance in fruit length was 70 cm2.
a. What is the standard deviation of the fruit length in the F2 generation?
b. What is the magnitude of the environmental variance in the F2 generation?
c. What is the magnitude of the genotypic variance in the F2 population?
d. What is the broad-sense heritability of fruit length in the F2 population?
e. Are most differences in fruit length in the F2 generation due to differences in genotype among the plants or to differences in environment?
