sodininkystė ir daržininkystė 25(4)

semi-dwarf rootstocks, such as M.26 or P 60 show good orchard performance on
light soils, on fertile ones they grow too vigorously (Skrzyñski and Poniedziaùek
1999). On the other hand, rootstock M.9 with its many advantages (Webster,
1992; Webster and Hollands, 1999) in some conditions is not winter hardy enough
(Czynczyk, 1979, 1997; Webster and Hollands, 1999) and suffers from droughts
(Czynczyk and Omieciñska, 1990; Makosz and Wùodarczyk, 1993). Therefore, it
is necessary to select the rootstock, which is best suited to our severe climatic
conditions. As rootstock of Polish origin are thought to be more frost resistant
(Zagaja et al. 1998), we tried to assess the performance of ‘Jonica’ trees, one of
the most popular cultivars in our orchards, grafted on Polish selection rootstocks:
P 22, P 59 and P 60 in comparison to standard ones: M.9 and M.26. The second
goal was to find a rootstock best adapted to soil and climate conditions, specific
for southern Poland.
Material and methods. The experiment was established in the spring of 1997
in the Experimental Station in Garlica Murowana, near Krakow. The soil of the plot
where the fruit trees were planted was in the valuation class II b. It is of the brown
soil type developed from loess and represents a species determined as silt loam. The
experimental material was composed of one-year-old budded trees of cultivar ‘Jonica’
on five rootstocks: M.9, M.26, P 22, P 59 and P 60. In the orchard the soil
cultivation system was herbicidal fallow in rows and grass in inter-rows. The apple
trees were spaced 1.0 × 4.0 m. The crowns of trees were trimmed in a slender
spindle form. The protection of the trees was carried out according to the recommendations
accepted for commercial plantations. However, no preventive spraying
with calcium salts was applied.
The experiment was established in a randomized blocks design, each treatment
being represented by four replications – plots of five trees each.
The following measurements and observation were made during the experiment:
Growth of trees was estimated as the increase of trunk cross-section area
(TCSA) measured at the height of 30 cm, for biennial periods. Additionally, the
crown volume was annually ascertained.
The flowering abundance was evaluated in scale 0 to 5, where 0 – no flowering,
5 – very intensive flowering. Some branches were labeled and flowers were
counted. In July fruit set was recorded.
At harvest, for each plot, the yield was weighted, the blush area and weight of
100 randomly chosen fruits was recorded. Moreover, the efficiency index was calculated.
The measurements were listed and subjected to analysis of variance. Differences
between the means were ascertained with a multiple Duncan Test, using a Statistica
6.0 program. The mean values for the combinations labeled with the same
letters do not significantly differ at the significance level α = 0.05.
Results and discussion. Used rootstocks significantly affected vegetative growth
of trees (Table 1 and Table 2). As far as trunk cross-sectional area is concerned, the
weakest tree vigour was obtained for P 22 and P 59 rootstock, stronger for P 60 and
M.9. Trees grafted on M.26 revealed the strongest vigour.
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