This study were conducted to know the morphological development, components, and functions of epicuticular waxes, and the influence of the cultivation environment of grape and the type of agricultural chemicals on the formation of epicuticular waxes, ...
This study were conducted to know the morphological development, components, and functions of epicuticular waxes, and the influence of the cultivation environment of grape and the type of agricultural chemicals on the formation of epicuticular waxes, using the grapes of ‘Campbell Early’, ‘Kyoho’, ‘Cheongsoo’ and ‘Hongisul’ cultivated in Korea.
When the epicuticular wax of the grapes of the harvesting season was observed with naked eyes, it had the form of opaque white powder on the skin of the grapes. L value of Hunter value was higher as well as berries that EWC was not damaged, and a value of Hunter value that is degree of red and b value that is blue degree were investigated that is lower
When the epicuticular wax crystals(EWC) development process, was observed, it was discovered that those four species shared a similar development process. One week before and during the full bloom, the surface of an ovary is covered with a cuticular ridge. As this cuticular ridge expands and divides itself, around three to six days after the full bloom, EWC begins to be formed in the type of a small berry among the cuticular ridge. Around twelve to eighteen days after the full bloom, the surface area of EWC is confirmed to become bigger so that it’s visible with a scanning electron microscope (SEM) and with naked eyes even though the fruits are very young. Afterwards, Shape of EWC were platelets with no particular direction in all the species of the grapes of ‘Campbell Early’, ‘Kyoho’, ‘Hongisul’, and ‘Cheongsoo’, and especially, ‘Kyoho’ and ‘Cheongsoo’ were observed to have a long linear platelets shape in addition to the platelets discovered in contrast two species.
As the ultra-structure of ‘Campbell Early’ were observed for to change after the harvest of EWC, in the part with no damage was keeping its platelets shapes observed during the harvesting time, and in case of the EWC in the physically damaged part, there were no more platelets remained which had been discovered during the harvesting time, and only rough film shapes.
Investigated development of the skin tissues aspect according to the major growth stage of grapes to search correlation between the changes of the morphology of the EWC and the skin tissues by that fruit develops. The result showed that the skin tissues of ‘Campbell Early’, ‘Kyoho’, ‘Hongisul’, and ‘Cheongsoo’ developed in a similar process. The epidermis was composed of a cell layer with one layer of tannin, and it was observed to be organized with tissues of similar size and shape at the time when the epicuticular wax can be recognized even with naked eyes displayed that. This result was different result with the fact that other this is always discovered from epidermis before or after that. Also, there was a thicker cuticle layer outside the epidermis by optical microscope than before even though there were some differences among the species.
Investigated components of epicuticular waxes, a qualitative analysis was conducted through GC-MS (Gas Chromatography Mass Spectrometry) on ‘Campbell Early’, ‘Kyoho’, ‘Hongisul’, and ‘Cheongsoo’. According to the result, the epicuticular wax was analyzed to be mainly made up of the aliphatic compounds of alkanes, alkenes, aldehydes, esters, fatty acids and primary alcohols.
Observing the relationship between the epicuticular wax and the quality of grapes in harvesting season, the main elements of the fruit quality, there were no significance the weight of the cluster, soluble solids, and total acid. This tendency was also similarly found in other kinds of grapes of ‘Kyoho’, ‘Hongisul’ and ‘Cheongsoo.’
The effects of the epicuticular wax on occurrence of Botrytis cinerea disease were studied with the ‘Campbell Early’ berries at harvest. Occurrence rate of the browning and a mycelium on the grape berries was 32% damage through hand, and 48% damage through gum arabic, which was respectively four and six times as much as the normal berries.
In addition, the disease occurrence rate, the components of the epicuticular wax and their correlation were examined through the inoculation against disease, using the extract of the grapes of ‘Campbell Early.’ As the result, the more extract was made from the epicuticular wax, the less mycelium grew. However, three days after inoculation, the same mycelium was observed to be growing in the one treated with equimultiple as the one with other treatment.
The result which measures the contact angle of the fruit skin non-bagging and bagging, were some differences depending on the grape species, in general, the contact angle on the skin of bagging whose ultra-structure of epicuticular wax was maintained properly was studied to be 139.1~149.8°. On the contrary, the contact angle of the fruit skin of non-bagging was 81.5~116.0°. It was significance lower than the contact angle in case of bagging.
As water soaking experiment was conducted using the grape berries of ‘Campbell Early’, the crack occurred 100 % in berries that epicuticular wax was removed by chloroform, and it took twelve days, which was about 2.6 times as fast as the berries whose epicuticular wax was normally formed.
Studied influenced of bagging or non-bagging and of the type of cultivation in ‘Campbell Early’. As a result, could confirm to bagging that epicuticular wax formation was very superior. Also, when cultivate without bagging, was observed that grape of cultivation under rain shelter is less epicuticular wax damage more than. On the other hand, did not differ greatly in cultivation type between open field and under rain shelter in case of bagging. The results were similarly with naked eye that observed ultra-structure of epicuticular wax by scanning electron microscope.
Stydied influences of different types of agrichemical as wettable powder, suspension concentrate, and emulsifiable concentrate for disease and insect pest control on the formation of epicuticular wax. As the result, when the berries treated with agrichemical at 15 days after the full bloom, was observed, even though it was treated with chemicals while it was young, the trace of chemicals was observed to still remain until harvest, and it was also confirmed that even on SEM. The berries of non-bagging that were treated with wettable powder and suspension concentrate chemicals at veraison were observed prominently trace of white chemicals which were difficult to be observed at berry setting. The results were similarly at berry setting that observed ultra-structure of epicuticular wax by scanning electron microscope.
Also, confirmed reformulation of epicuticular wax after give physical damage to cluster at veraison when epicuticular wax was observed. As the result, epicuticular wax damage region did not get back to that coloring was proceeded.