Stomatal density and distribution in different cassava genotypes

This study aimed to establish the anatomical characteristics, and to determine the density, size and distribution of stomata in the abaxial surface of leaves of different cassava genotypes. The apical, middle and basal portions of fully expanded leaves of genotypes Baianinha, Caapora, Fecula Branca, IAC 12, IAC 13, IAC 14, IAC 15, IAC 576, IAC 90 and IAPAR Uniao were analyzed. The design was completely randomized with a 3 by 3 factorial arrangement and three replications, and the data were analyzed by Anova and Scott-Knott test. The parameters evaluated concerned the number, polar and equatorial diameters of stomata and calculations of density and stomatal functionality. Significant interaction was found among the different genotypes and the distribution and size of stomata in the different parts of the leave, being more frequent in leaf apices. The genotypes Baianinha, Caapora, IAC 576 and IAPAR Uniao characterized the group with the highest stomatal density, while the genotype IAC 90 showed the lowest density and the largest polar diameter, regardless of the location of the stomata. In the analyzed leaves, the lowest polar diameter was detected in the genotypes Baianinha, Caapora, IAC 14 and IAPAR Uniao, while the largest equatorial diameter was found in IAPAR Uniao. In all genotypes, functionality was inversely proportional to stomatal density, with a negative correlation between stomatal density and the polar diameter of stomata.   Key words: Manihot esculenta Crantz, Papillae cells, stomata paracytic, scanning electron microscope.