Fig. 2. Temperatures at inflection point (50% sterile males) in parents, F₁, F₂ (white circle) and of successive backcrosses (see Table 2). (A) The Y chromosome of Delhi is introduced into the Prunay background. (B) The Y chromosome of Prunay is introduced into the Delhi background. Horizontal arrows in each graph show the temperatures at inflection point of the two parental lines: Delhi (top) and Prunay (bottom). From G₃ to G₆, values are not different and the mean is illustrated by a dotted line. The respective roles of Y and genetic background are indicated.