sodininkystė ir daržininkystė 25(4)

any significant effect on fruit sizes and were in general medium to small for both
cultivars. Smallest fruit size was recorded on the ‘Reine Claude’ (Tables 3 and 4).
For all cultivars the fruit weight decreased with increasing crop (data not shown).
Similar pattern was found for the content of soluble solids (Table 4). Fruit quality
characterized by the content of soluble solids was high for ‘Reine Claude’ with
average 20% and 15% for ‘Opal’ However, plums from trees on Ferlenain had significant
higher content of soluble solids for both cultivars.
Tree survival. The winter of 1995/96 was special in the way that it came frost
from the end of November until the end of March without any snow cover. Under
these climatic conditions the root systems became partly damaged on some of the
rootstock and cultivar combinations. The rootstocks Ferlenain was the least frost
tolerance with 50% and 20% of the trees lost on the two cultivars ‘Opal’ and ‘Reine
Claude’, respectively. The rootstocks Fereley and St. Julien A were the most winter
tolerant with all trees surviving the test period of 8 years.
Discussion: The objectives of the breeding programme at INRA Bordeaux
was reducing the vigour of the rootstocks, early bearing, heavy and regular production
and type of branching and fructification leading to faster pruning and
lower production costs (Renaud and Salesses, 1994). The first minor yield was
not achieved until the third leaf for ‘Opal and fifth leaf for ‘Reine Claude’. The
trees suffered some the first growing season likely due to root drying under transport.
However, from the second leaf and the rest of the test period, normal annual
growth was achieved.
Plum trees are generally slow to come into bearing. However, the ‘Opal’ trees
started to crop earlier than ‘Reine Claude’ independent of rootstock choice. The
dwarfing rootstock showing most promise in this trial was Ferlenain for ‘Reine
Claude’. Mature trees on this rootstock were significant smaller than the other rootstocks
except Fereley. Total cumulative yield and yield efficiency from these trees
on Ferlenain was significant better than on the other rootstocks. Similar effect by
this rootstock on the cultivars ‘Victoria’ and ‘Czar’ is reported by Webster and
Wertheim (1993). Trials in France have shown similar results as well with prune and
gage trees on Ferlenain dwarfing the trees and to yield good size fruits with no
incompatibility problems for ‘Green Gage’ (Bernard and Renaud, 1990). At bloom
time in the third – sixth leaf the amount of flowering were judged. Across all cultivar
and rootstock combinations the Ferlenain rootstock got the highest scores and this
effect was clearly demonstrated for the cultivar ‘Reine Claude’.
However, half of the Ferlenain trees did not survive in the ‘Opal’ trial and they
yielded less than the other rootstocks.
The rootstocks Ferciana, P 8–13 and the standard St. Julien A did not dwarf the
two cultivars significantly and the cumulative yields during the experiment per tree
were in the same area. No significant differences in the average fruit size where
found for the different cultivar/rootstock combinations. Fruit size is linked to the
cultivar and the crop load on the trees. These trees had moderate large yields and
likely got no fruit size reductions.
The content of soluble solids are important components of plum quality. This
component was not strongly influenced by the rootstocks and only minor differen-
184