EVOLUTION OF PHOTOSYNTHESIS IN GENOTYPES OF CONILON COFFEE THROUGHOUT THE REPRODUCTIVE PHENOLOGICAL CYCLE

Abstract

Knowledge about the photosynthetic performance of genotypes of Conilon coffee is crucial for identifying the most efficient and resilient plants, thereby boosting procuctivity. In this context, the objective was to study the variability among 27 genotypes of Conilon coffee regarding photosynthetic characteristics during each phenological stage of the reproductive cycle, as well as to understand the evolution of gas exchange in the genotypes throughout these stages. To achieve this, the experiment was conducted using a split-plot design, with 27 genotypes forming the main plots and four stages of the reproductive cycle forming the subplots. The experiment followed a randomized block design with four replications, and each plot was composed of six plants. During each phenological stage (flowering, pinhead, fruit expansion, and maturation), net CO2 assimilation rate, stomatal conductance, transpiration rate, and substomatal CO2 concentration were evaluated. The results showed high photosynthetic variability among genotypes of Conilon coffee, with stomatal conductance being the variable that allowed for the greatest differentiation among genotypes. Genotype 108 showed the highest photosynthetic rates, especially during fruit expansion, while genotype 209 had the lowest. Genotypes 104, 106, 306, and 307 showed a trend of greater photosynthetic stability throughout the fruit development cycle. Information on the photosynthetic aspects of coffee plants can be used to select genotypes in genetic improvement programs, based on adaptive capacity, photosynthetic efficiency and specific characteristics, especially in the face of climate changes.