Respostas anatomofisiológicas de clone de Coffea canephora submetidos ao manejo de irrigação do Cerrado do Planalto Central

Abstract

The Brazilian Cerrado region has great productive potential for coffee culture, participating in approximately 40% of the national scope. This fact is due to the fact that it has a favorable climate for cultivation, topography, use of cultivars and more adapted clonal seedlings, irrigation system, among others. In addition, taking advantage of the irrigated system and the well-defined climate, suspension of irrigation can be carried out in the winter period, aiming at flowering synchronization, resulting in greater production of cherry fruits. The objective of the present study was to evaluate the behavior of Coffea canephora clones submitted to irrigation management in the Cerrado do Planalto Central through evaluations of anatomical, physiological and biochemical characteristics, for the selection of plants that are more adapted to the growing environment. The evaluations were carried out in six clones of the species Coffea canephora, four of the Robusta variety and two of the Conilon variety, of which one is drought tolerant (clone 14) and the other sensitive (clone 22). Evaluations were carried out in four periods, in the years 2016 and 2017, comprising before (APSI) and at the end (FPSI) of the irrigation suspension period, two days (2dARI) and three months after the return of irrigation (3mARI). Leaf anatomical characteristics such as density and ratio of polar and equatorial diameter of stomata, diameter, number and frequency of xylem vessels, total xylem area, total phloem area, vulnerability index and relative hydraulic conductance were evaluated. The physiological characteristics analyzed were liquid photosynthetic rate, stomatal conductance, transpiratory rate, water use efficiency, carboxylation efficiency, leaf water potential, potential quantum efficiency of photosystem II, chlorophyll A, B and total indices and relative water content. The enzymatic antioxidant system was also evaluated using superoxide dismutase, catalase and ascorbate peroxidase and non-enzymatic with ascorbate quantification. To assess the stress caused, hydrogen peroxide, lipid peroxidation and electrolyte leakage were quantified. Clones 14, 8 and 125 showed similar behaviors and greater development of characteristics to survive the farming environment, such as changes in gas exchange, relatively high water potential under water deficiency, efficiency in water use, development and alteration in xylemic vessels, responsible water transport. Clone 30, on the other hand, showed greater sensitivity, similar to clone 22, with greater oxidative damage when exposed to water deficit. Clone 114, on the other hand, had an intermediate survival mechanism. It is concluded that the clones presented different adaptation and survival strategies in the face of the imposed water deficit.