Page 447 - Biosystems Engineering

Exogenous Bior egulators–Fruit Composition & Storability 423

The results presented here are a further proof of the complicated
influence of growth regulators on plant mineral composition. How-
11
ever, the collected information can not be used to control apple tree
nutrition in practice, but they have broadened our knowledge of the
influence of growth regulators on mineral uptake and distribution.
The retardants tested—daminozide and paclobutrazol—are solely
the examples of preparations used for plant growth retardation.
Application of the obtained results should be facilitated so that we
may learn more about other new retardants.

15.3 Influence of Retardant and Auxin Treatment
of Apple Shoots and Fruits on Calcium Uptake
and Distribution
Calcium plays an important role in fruit physiology, especially in
fruit ripening and in preventing physiological diseases in stor-
age. 1,17,25,27,62,64 These phenomena are controlled by endogenous hor-
mones 23,58 to a great extent and are also modified by the application of
growth regulators. 41
Hormonal regulation in a plant is connected at many points with
calcium physiology of the cell. 16,71 In addition, typical acropetal trans-
port of calcium in a plant is dependent on the polar basipetal translo-
cation of the auxin. 2
Retardants may influence calcium uptake in a fruit probably by
changing the activity of physiological sinks. Suppressing vegetative
growth with a retardant may diminish the sink activity of the long
shoot apex and young leaves. Retardants may change some features
of the fruit and, therefore, may also influence the sink activity of cal-
cium in the fruit itself. 26
This recent investigation analyzed calcium uptake and distribu-
tion in apple shoots and fruits as affected by the growth retardant
daminozide, which is supposed to diminish the competition between
young fruits and their vegetative parts. In separate treatment, auxin
was also applied to the fruits, in untreated shoots and in retardant
treated ones, to augment their sink activity (as previously supposed).
The investigations were carried out from 1987 to 1988, on 19- and
20-year-old Double Red Mclntosh apple trees grafted onto Antonovka
seedlings. The trees were from the Pomological Orchard of the Insti-
tute of Pomology and Floriculture in Skierniewice, Poland, and had
round, almost natural, crowns.
To diminish the growth of current-year shoots, daminozide was
applied 2 weeks after flowering. The compound was used at a con-
centration of 0.2 percent, and the chosen branches were sprayed once
in two ways: whole branches (including shoots and fruits) or only