Page 466 - Biosystems Engineering

438 Cha pte r F i f tee n

SADH applied against a preharvest fruit drop stimulates devel-
opment of core flush of apples during storage. McIntosh apples, the
cultivar commonly cultivated in Poland, are particularly sensitive to
65
this disorder. A similar problem was reported in the United Kingdom 61
for the Cox Orange cultivar. To improve the storage ability of apples,
it is recommended to spray or dip the fruits with calcium chloride.
Calcium was reported to prevent apples from several storage disor-
ders, among them the core flush. 15,49,50 One of the points of this chap-
ter was to investigate the influence of calcium chloride on the quality
of apples sprayed with SADH, with particular attention to the occur-
rence of core flush during storage.
Experiments were carried out from 1983 to 1984 at two experi-
mental stations of the Institute of Pomology and Floriculture—Prusy
and Sinoleka—on mature McIntosh trees.
Alar 85 (SADH, succinic acid-2-2-dimethylhydrazide) was
applied at a concentration of 0.1 percent in the middle of July (about
60 days before harvest from untreated trees). Half of the trees had
additionally been sprayed 5 times with 0.8 percent calcium chloride
(CaCl × 6 H O). The first application was done at the beginning of
2 2
July, three others every 2 weeks, and the last one a week before the
harvest of apples from untreated trees. Untreated trees and trees
sprayed only with calcium chloride were used as controls. Half of the
trees in each treatment were sprayed with Pomonit R-10 (NAA,
1-naphtaleneacetic acid) for apple thinning. It was applied at a con-
centration of 0.04 percent 2 days after bloom.
Observations were made to establish the influence of the treat-
ments on fruit quality during harvest and, in the case of unthinned
trees, also on fruit quality during storage. Additionally, the storage
ability of apples sprayed with SADH and dipped immediately after
harvest in 4 percent solution of calcium chloride were investigated.
Apples were kept in cold storage at temperature of 3°C and relative
humidity of 85 to 92 percent. In the second part of December and
at the end of January and the beginning of February apples were
examined for their firmness and the occurrence of physiological
disorders.
Experiments were also carried out to determine the influence of
treatments with SADH and calcium chloride on the content of cal-
cium, potassium, and magnesium in apples during the last month of
storage. The level of the components was investigated using the
absorption spectrophotometer method.
Apples from trees sprayed with SADH were harvested 2 weeks
later than those from other treatments. An investigation of each treat-
ment was done on apples collected from seven uniform trees selected
according to their growth and bearing. Results of the experiments
were calculated statistically with analysis of variance, and the signifi-
cance was evaluated using Duncan’s t test at P = .05.