RESPONSE TO PACLOBUTRAZOL APPLICATION AND WATER DEFICIT ON LEAF ANATOMY OF TWO OLIVE TREE CULTIVARS

Information about the anatomical leaf behavior of the olive tree is essential to both the establishment and management of crops in different growing regions. One alternative to encourage the cultivation of olive tree under the Brazilian conditions may be through the vegetative growth control and thus provide increased flowering. This practice can be accomplished with the application of growth regulators from the group of growth retardants. To compare the effects of water deficit and paclobutrazol on the leaf anatomy of two olive cultivars, a trial was conducted using a factorial scheme 4×2, the factors being four doses of paclobutrazol (PBZ) [(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1h-1,2,4-triazol- 1-yl) pentan-3-ol]: 0, 5, 10 and 15 ml per plant and two levels of water restriction: daily irrigated plants and plants submitted to water deficit, distributed in a completely randomized design with four replications. Eighteen-month-old plants of the cultivars ‘Koroneiki’ and ‘Arbequina’ grown in pots with a capacity of 10 L were studied. The application of PBZ was done by diluting the quantities established in 500 ml of water and applied to the substrate and 90 days after the application of PBZ, half the plants were submitted to water deficit. The water restriction to plants was determined by suspending irrigation during 30 days. For anatomical studies, two olive cultivars ‘Arbequina’ and ‘Koroneiki’ were comparatively studied in irrigated and water deficit plants and submitted to PBZ application. The plants’ leaves submitted to water deficit showed thicker epidermis and a decrease in the size of the mesophyll cells and leaf area. The two olive cultivars under water deficit showed anatomical changes in the leaves to reduce water losses. The application of paclobutrazol does not interfere with protective mechanisms developed by the plants to tolerate water deficit and reduced the size of the leaves in the olive cultivars ‘Koroneiki’ and ‘Arbequina’, showing the possibility of its application to growth control of the olive tree.