GENETIC STABILITY BY FLOW CYTOMETRY AND STEM ANATOMY CHARACTERIZATION OF CITRIC PLANTS IN THE GRAFTING PROCESS

The objective of this study was to evaluate changes in the DNA content as well as in the stem anatomy of grafted citrus cultivars. In the first experiment, the DNA content of plants formed by oranges ‘Navelina’, ‘Lane Late’ and Navelate and mandarins ‘Clemenules’, ‘Ortanique’ and Okitsu’ grafted in rootstocks of citrandarins ‘Índio’ and ‘San Diego’, mandarin ‘Sunki Tropical’, rangpur lime ‘Santa Cruz’ and citrumelo ‘Swingle’ were evaluated. Leaves and roots of each cultivar in all possible scion-rootstock combinations were used, totaling 30 treatments. DNA contents were assessed by flow cytometry. Significant statistical differences were found in the DNA contents of scion leaves, which varied according to the rootstock used. In the second experiment, cross and longitudinal sections of stem were performed in the grafting region. Cultivars ‘Navelina’ and ‘Clemenules’ were evaluated in a factorial arrangement with four rootstocks, in a completely randomized design. The height of rays and vessel diameter were measured. Larger diameters of xylem vessels in the scions were observed for ‘Clemenules’ in almost all rootstocks tested. For height of rays, the results were quite variable in all combinations scion/rootstock studied, with formation and proliferation of disorganized cells in the connection of vascular elements between scion and rootstock. This study is important as it contributes to the understanding of the interactions between scions and rootstocks in citrus, revealing how these combinations can influence both DNA content and wood anatomy, providing valuable information for the selection of combinations that optimize plant development and productivity.