Page 455 - Biosystems Engineering

Exogenous Bior egulators–Fruit Composition & Storability 429

attached. Then the fruit can take advantage of this better vascular
connection of the short shoot that sustains it.
Plants treated in such a manner showed the greatest uptake of the
radioisotope by whole-plant segments (Table 15.3). Pinching had no
influence on the uptake of calcium by fruits but significantly increased
45
the amount of Ca per unit of fresh mass in short shoots. At the same
45
time, the uptake of Ca by long shoots diminished markedly.
The great increase of calcium uptake by a whole segment may be
tentatively explained, taking into account that about 4 weeks passed
from the time when the long shoots were pinched to the time when
the radioactive calcium was applied. During that time, two or three
lateral buds started to develop and probably substituted the lack of
terminal apex with their own auxin. The high supply of calcium in
these segments caused a large amount of Ca to accumulate (possibly
45
transitory) in the burse. Although the fruits did not have a great rela-
tive share in the total calcium that was taken up, their share was great
in absolute units.
In interpreting the results of this chapter, it should be taken into
account that the experiment consisted in feeding with Ca fragments of
45
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branches by their cut lower end. Faust and Shear have shown great dif-
ferences in Ca transport in cut branches and in noninjured seedlings.
In comparison with the research of other authors, this work intro-
duces more factors that could influence calcium uptake. For instance,
more growth regulators were applied. Besides retardant, auxin and
gibberellin and combinations of auxin with retardant were also used.
Instead of fruits alone, the whole system composed of a fruit, a short
shoot, and long shoots was investigated. From the point of view of
methods the retardant was applied to the whole system as well as to
shoots only (excluding the fruit). This might demonstrate whether
the influence of retardant on the fruit is direct or indirect.
The calcium uptake in such a set of combinations confirms the
opinion of Faust and Miller and Tromp that calcium uptake by the
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apple depends on many factors.
Growth regulators may influence the calcium content of fruits,
but the effect is not always repeatable, depending on environmental
as well as physiological factors.

15.4 The Effect of Fruitlet Thinning Using Bioregulators
on Mineral Content and Storage Quality of Fruits
It is well known that the storage ability of fruits depends on condi-
tions prevailing during their growth and storage. One of the main
measures that modifies fruit growth is flower or fruitlet thinning.
The effect of thinning on apple size and their attractiveness is well
documented. 8–10,20,38,44,75,76 Much less information exists concerning the
influence of fruitlet thinning on the storage ability of apples.