Anatomia do xilema secundário e potencial hídrico em cultivares de videira

Abstract

Brazil is a major grape producer, especially for wine production. This study evaluates the vessel diameter and density of secondary xylem, as well as the water potential in three grape cultivars (‘Bordô’, ‘BRS Violeta’, ‘Niágara Rosada’) and the rootstock Paulsen 1103. The main objective was to assess water dynamics in these cultivars in the southern region of Brazil, aiming to increase the productive potential. The experiment was conducted at the Federal University of Pelotas, using grapevines cultivated in pots in a controlled environment. The substrate used was a 1:1 mixture of soil and carbonized rice husks. Histological sections were made from the median portion of the stem, obtaining five 15centimeter-long branches from each plant. Each branch was divided into three 5 centimeter sections, with two cuts made for each section, totaling thirty samples for each cultivar for the analysis of vessel diameter and density under an optical microscope. Measurements were performed using the ImageJ program, and statistical analyses were carried out using the Rbio software. Water potential was measured with a Scholander Pressure Chamber. The results showed that Paulsen 1103 had the largest vessel diameter and density in the secondary xylem, resulting in more efficient water conduction. BRS Violeta demonstrated advantages under high water demand conditions, while Niágara Rosada was more efficient under water stress conditions. Paulsen 1103 also exhibited a less negative water potential, indicating better adaptation to drought conditions. The results indicate that Paulsen 1103 is a good choice for regions with low water availability, while the cultivars have specific advantages that can be exploited according to agricultural needs.