Biochemical characterization of Tunisian grapevine varieties

<p style="text-align: justify;">61 tunisian autochton grapevine varieties have been collected for biochemical identification. Isozymes analysis with starch gel electrophoresis technique was used to confirn or to cancel random denominations awarded to the majority of these local varieties. In our conditions, concentrated plant extracts were obtained from vigorous donnant canes newly cut off from selected mother plants during automn. These allowed us to dispose of rigorously interpretable isozyme banding patterns of GPI and PGM systems and to overcome difficulties often related to the use of PGM system. The study of GPII and PGM enzyme systems allowed us to classify the autochton accessions into 16 different groups from which 5 groups containing only 2 or 3 varieties.</p><p style="text-align: justify;">On the other hand, the study of AAT and peroxydase enzyme systems has shown stable and legible isozyme banding patterns allowing to discriminate between equivalent accessions such as Sakasly and Kahli (two black local vines very similar), 3 varieties of Bidh Hamem (Bidh Hamem, Bidh Hamem Rafraf and Bidh Hamem Sfax), and 2 varieties of Bezzoul Kelba Bidha (Sfax and Gabes). In addition, certain varieties having for longtime the same denominations were characterized. A case of point the 4 varieties Khalt meaning mixture (Bouchemma, Abiedh, Mdaouer and Souche 1) and the 3 varieties of Arich (Ahmar, Dressée, and Jerba) were proved to be completely different from each other. In the same way, Bezzoul Khadem has been differed from Hemri variety. The complementary use of berry colour allowed to discriminate between Saouadi, Khdhiri and Jebbi varieties and to subdivise the remainig groups into sub-groups.</p><p style="text-align: justify;">The study of GPI, PGM, AAT and peroxydase isozyme banding patterns in combination with berry colour has led to establish a classification of the 61 autochton varieties into 37 groups including 26 varieties definitely differentiated through the results of this biochemical study.</p>

Effect of N-dimethylaminosuccinamic acid on Cabernet Sauvignon grapevines

Alar (R) (n-dimethylaminosuccinamic acid) was sprayed at concentrations up to 4000 p.p.m. twelve and five days before and at full bloom in one experiment, and to 8000 p.p.m. at the seven to eight leaf stage in a second experiment to single whole vines of Vitis vinifera cv. Cabernet Sauvignon. All concentrations of the growth retardant on all dates reduced berry weight in the first experiment, but only 4000 p.p.m. and 8000 p.p.m. had that effect in the second experiment. Berry number per bunch was increased by sprays of 1000 and 4000 p.p.m. twelve days before flowering in the first experiment, but bunch weight and yield per vine were not affected by treatment. In both experiments, maturity was delayed by treatment. Berry colour was reduced by 4000 p.p.m. Alar application twelve days before full bloom and at full bloom in the first experiment; a similar tendency occurred as a result of the 4000 and 8000 p.p.m. treatments in the second experiment.