Morfofisiologia, anatomia foliar e produtividade de clones de café conilon no cerrado central

Abstract

The Central Cerrado region has great potential for coffee growing, due to its climatic characteristics associated with the possibility of adopting irrigation management techniques, such as the suspension of irrigation in the winter period, to synchronize flowering. Conilon coffee cultivars, with different fruit maturation cycles, launched by the Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (Incaper) in 2013, are highly productive under irrigated conditions, however, they still need to be evaluated under Cerrado conditions. In this sense, the objective was to evaluate the performance of clones of the cultivars Jequitibá Incaper ES8122 and Centenária ES8132, through physiological, anatomical and biochemical foliar analyses, as well as growth and grain yield, in an irrigated system with a period of controlled water deficit, in the Central Cerrado region. The analyzes were performed on clones of two cultivars of Conilon, five clones of the cultivar Jequitibá Incaper ES8122 (intermediate cycle) and six of the cultivar Centenária Incaper ES8132 (late cycle). Irrigation management with controlled water deficit of approximately 64 days was adopted. The evaluations were carried out in three periods, being: end of the water suspension period (FPSI), two days after the return of irrigation (2dARI) and three months after the return of irrigation (3mARI) in 2019 and 2020. The physiological characteristics analyzed were gas exchange, pre-morning water potential, chlorophyll a, b and total and relative water content. Leaf anatomical characteristics were evaluated: adaxial cuticle thickness, leaf blade thickness, stomatal density and functionality, total area of the phloem region, area and frequency of xylem vessels, diameter of xylem vessels, relative hydraulic conductivity and index of xylem vulnerability. Regarding the biochemical analyses, the levels of hydrogen peroxide, malondialdehyde, activity of catalase enzymes, superoxide dismutase, ascorbate peroxidase, ascorbate levels and carbohydrate metabolism were measured through the quantification of starch and total soluble sugar. Grain yield, plant height, canopy projection and leaf area index were also evaluated. Considering the clones of the Jequitibá cultivar, clone 207 showed the highest grain yield, and it was related to the variables xylem vessel diameter, relative hydraulic conductivity, net photosynthetic rate, higher starch content and activated the antioxidant defense system. Clone 203 presented intermediate productivity which was related to variables related to conducting vessels and starch content. Among the clones of the cultivar Centenária, clone 302 revealed the highest productivity, the highest relationship with the diameter of xylem vessels and relative hydraulic conductivity, net photosynthetic rate, water use efficiency, higher values of plant height, canopy projection, index of leaf area, and activated the antioxidant defense system. The variables plant height, canopy projection, starch and total soluble sugar indicated positive relationship with productivity. The clones of both cultivars showed potential to be used in the Central Cerrado region conditions, in an irrigated production system, and clones 203, 207 and 302 also can be used within the breeding program, as parents.