Inheritance of growth curve

There have not been reported, so far as is known to the writer, any studies on inheritance of the growth curve which expresses the entire course of development of plants, except by Ashby. According to his investigations, the logarithmetic growth curve of F1 which was obtained from corn plants during the vegetative period of growth, that is, from emergence to 70 days afterwards, was quite the same as the curve obtained from one of the parents, indicating that complete dominance occurred in this case. In the present study, by using wheat plants, attempts were made to determine whether the growth curve produced by the employment of Robertson's growth equation is inherited. In Robertson's growth equation, the constant K is of special significance for the investigation of inheritance of growth curve because the slopes of growth curves are affected by variations in the magnitudes of the constant K. Since it has been pointed out by Copeman, Klages, and Iwamoto that the values of constant K are greatly affected by environmental factors, all plants of parents and progeny were cultivated under as nearly uniform conditions as it was possible to obtain. Under these circumstances, the values of K were calculated from the data obtained from weekly height measurements. According to the results thus obtained, the values of K in F1 hybrids were intermediate between those of the parents and the same average values were obtained in F1 reciprocal crosses. Furthermore, in F3 progeny, such results were obtained that the frequency distribution of K of each family was considerably different, showing that each family Presented its own independent phenotype. From these F1 and F3 results, the author arrived at the conclusion that the constant K may be inherited according to the Mendelian rule. If this is so, the next question is, what factors are involved in the production of constant K? In reply to this question, the writer wishes to state that multiple factors may be involved in the control of values of K in view of the results of F2 in which frequency distribution was transgressively segregated.