INHERITANCE OF LATE LEAFING AND LATERAL BUD FRUITFULNESS IN WALNUT (JUGLANS REGIA L.), PHENOTYPIC CORRELATIONS AMONG SOME TRAITS OF THE TREES.

In France, the Fruit Research Station of Bordeaux started a walnut variety breeding program in 1977. Twenty-two crosses have been carried out so far.
French, late leafing, blight tolerant varieties with good nut quality, choosen as female parents, were pollinated by Californian varieties with early bud break but fruiting on lateral bearers and thus heavy producing.
In 2450 hybrids observed, 37.2 p.cent of seedlings ranged from medium late to very very late leafing.
This percentage depended mainly on the earliness of parents used.
In all of these progeny, there was a percentage often around 20 p.cent, of extremely late leafing hybrids which have no agronomical interest.
The analysis of collected data showed a high correlation between the leafing time of one-year-old seedlings in the nursery and this parameter observed, some years later, on the same trees, in selection plots (r = ± 0.78). Therefore it was possible to do an early sreening for late leafing as soon as the uprooting from the nursery.
In 730 late bud breaking hybrids studied here, about 10 p.cent fruited on lateral bearers as their Californian parents.
This percentage was higher in early leafing ones.
The lateral bud fruitfulness character was also fairly correlated with moderately spreading or spreading growth habit.
The lateral fruit bearing hybrids are very early producers, having a high yield potential and most of them bearing catkins as soon as 6 years of age.

I International Symposium on Walnut Production

E. Germain

https://doi.org/10.17660/ActaHortic.1990.284.15