Under some laboratory conditions, it is possible to obtain a production of anthocyanins by the leaves of grape cuttings.
The objective of this work consists in the comparison between contents in anthocyanin pigments of leaves of stemming Carignan of one eye cuttings cultivated in various conditions of laboratory with those of leaves of the same cultivated grape to the vineyard in the area of El Khenguet UCP Sidi Slama (Tunisia).
We have measured the growth in length and in diameter of stems of the cuttings processed 30 days in total darkness and compared to cuttings witnesses raised in greenhouse. The same comparison has been undertaken on cuttings having undergone 30 days stay in total darkness and 21 days of maintenance in greenhouse with witness that has undergone 51 days in greenhouse.
The total darkness during 30 days favors the growth in length and in diameter of shoots, reduced the leaf surface, and blocks the synthesis of anthocyanin as compared to the photoperiod of 12 hours of darkness/12 hours of light. The total darkness during 30 steady days by a photoperiod of 12 hours light/12 hours darkness during 21 days induces a resumption of the leaf growth and a synthesis of anthocyanins in leaves and in stems.
The analysis of the anthocyanin, undertaken by High Performance Liquid Chromatography (HPLC) allowed to detect the five anthocyanin 3-monoglucosides following: Delphinidin MG3 - Cyanidin MG3 - Petunidin MG3 - Pæonidin MG3 and Malvidin MG3.
They are in the free form and in the combined form, esterified by acetic, cafeic and coumaric acids in stemming leaves of the vineyard as well as in those developed in the laboratory. The combined anthocyanins are better represented in the cutting cultivated in laboratory.
The Cyanidin 3-monoglucoside, the Pæonidin 3-monoglucoside and the Malvidin 3-monoglucoside present a maximal content at the period of the fall of leaves. The other anthocyanin pigments have similar contents always weaker than those of Cyanidin MG3 and Pæonidine MG3.
The output in total anthocyanin obtained of the cuttings of the laboratory is equal to 25 p. cent of that of the vineyard.
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