Physiogenetic researches on the crosses L. hirsutum x L. esculentum (var. Palla Oro, Comet, Cuor di Bue) confirm the results already emerged from researches on F2 and F3:
1) - No correlation between vitmin C content and carotenoid content in fruit.
2) - The gene B, responsible for the B-carotene synthosis, is not present in common red-fleshed varieties. Such conclusion has been confirmed by the results obtained by Tomes, Quackenbush, Nelson and North on their crosses between yellow, red -orange, and tangerine varieties.
3) - In F4 a full range of phenotypes occurs: high lycopen and low carotene content, high carotene and lycopen traces, equal content of both pigments, red orange fruits with high content of both. The synthesis of the two pigments is made through distinct precesses, controlled by two independent genic systems. This conclusion is confirmed both by my researches on the effect of high temperature on maturation, and by the recent studies of Goodwin and Malini Jamikorn.
4) - Very important for selection is the occurrence of phenotypes having high content in provitamin A and in vitamin C - equal at least to that of common cultivated varieties - and in lycopen (mg.% B-carotene 7.05-8.15: lycopen 16.70-1550; ascorbic acid 35).