STOMATA AND VIGOR OF ‘VALENCIA’ ORANGE SCIONS GRAFTED ON ROOTSTOCKS TOLERANT TO THE CITRUS TRISTEZA VIRUS

Abstract

The main problem that citrus growers face is diseases that affect trees. For this reason the use of rootstocks has spread, and the challenge is to obtain the best scion/rootstock interaction. The present work evaluated the scion/rootstock interaction in function of tree height and canopy diameter of ‘Valencia’ orange (Citrus sinensis L.) grafted onto three tolerant VTC root-stocks: ‘Volkamerian’ lemon (Citrus volkameriana Ten. and Pasq.), and the tangerins ‘Cleopatra’ (C. reshni Hort. Ex Tan) and ‘Amblicarpa’ (C. amblycarpa Ochse), from 4 to 9 years old trees. The measurements were done for a period of five years, and during the last year stomatal density and size, and leaf area were evaluated. The plants grafted on ‘Volkamerian’ and ‘Amblicarpa’ had similar plant height and canopy diameter (3.3 m vs. 3.4 m and 3.2 m vs. 3.5 m, respectively). The plants on ‘Cleopatra’ presented the lowest values (2.9 y 2.7 m). There was no difference in stomatal density and length of ‘Valencia’ orange although stomatal width differed. Stomata shape (length/width relationship) was modified; in plants grafted on ‘Volkamerian’ he was rounder (1.14), and on ‘Amblicarpa’ it was more elliptical (1.23). There were no correlations between vegetative variables and stomatal density and size.