Genetical studies of quantitative characters in peas. 3. seed and seedling characters in the F₂ of a six-parent diallel set of crosses

Summary

Very little information is available on the genetics of seed size and the initial stages of plant development in peas. An experiment involving F₂ material available from a full 6 x 6 diallel set of crosses involving 2 wild forms, 2 primitive and 2 European cultivars was set up to investigate a number of plant characters. These were seed weight, seedling shoot and root length and the number of lateral roots at 6, 7, 8 and 9 days after germination, and shoot and root fresh weight at 9 days.

The 6 x 6 diallel was reduced to a 4 x 4 as two of the primitive form parents each contained a single reciprocal translocation in relation to the remaining four parents.

Polygenic control was found for all characters examined, principally additive for seed weight, but with dominance being important for the seedling characters. Large differences were found between the primitive types and the cultivars with respect to fresh weight of shoot and root, and the number of lateral roots. It is suggested that those differences results from unconscious selection by plant breeders.

A number of mature plant characters, time to flowering, flower number per node and ovule number per pod both at the first and second flowering nodes were also investigated. Genotype-environment interactions appear to account for the different results found in this experiment with F₂ material from those in the F₁ which was grown in the previous year.