Grapevine yield components and composition of Isabel grape produced according to the organic and conventional systems

Abstract

Abstract. There is an increasing demand for organic grapes by the juice industry of Serra Gaúcha, Brazil. This region presents a humid and hot summer, ideal climatic conditions for the development of a number of diseases. To control such diseases and problems brought about by other organisms, growers apply pesticides on the grapevines which may leave residues in grapes. However, in general, grapes produced by organic system have lower yield, but there is a lack of research data on this subject. Thus, an experiment was carried out over three years in order to compare the yield components and the physicochemical composition of the must of Isabel grapes conducted in both production systems. When the grapes were ripe, variables related to yield components were evaluated, such as the number of clusters/vine, yield/vine and weight/cluster. Then the grapes were sampled and taken to the laboratory where they were crushed and the musts were centrifuged and analyzed. The 3-year data mean were submitted to correlation analysis and Principal Component Analysis. The results show that conventional grapevines produced 2.18 times more than organic. However, the grapes from the organic system had higher density, Brix, pH, Brix/titratable acidity ratio, P and Mg but lower K, and Ca varied little between both production systems.

Accumulation of Phenolic Compounds and Antioxidant Capacity during Berry Development in Black ‘Isabel’ Grape (Vitis vinifera L. x Vitis labrusca L.)

“…Their results indicated that, in the anthocyanin biosynthesis pathway (ABP), genes may be regulated by ABP-specific regulatory factors, and their expression levels may be strongly associated with anthocyanin pigmentation, or they may be expressed independently of pigmentation. It has been known that ‘Isabella’ grape varieties are resistant to fungal diseases and they can be grown in regions with cool and humid climates [ 28 ]. ‘Isabel’ (or Isabella) grape varieties used for grape cultivation in Black Sea region are not affected by fungal diseases, there is no need for the use of drugs in the grape’s cultivation, but some nematodes can cause serious leaf and fruit losses, especially in black ‘Isabel’ grape (reference: personal communication with authorities in Republic of Turkey of Ministry of Agriculture and Forestry-Trabzon Directorate of Agricultural Organization).…”