Intensidade da coloração verde foliar em genótipos de Coffea Canephora: divergência genética e relação com o desempenho fotossintético

Abstract

The selection of genotypes with superior photosynthetic performance is essential for obtaining substantial gains in breeding programs, since understanding about the physiological aspects of coffee, reflected in photosynthetic performance, can contribute to increasing crop productivity. However, for the characterization of phenotypes (phenotyping), the main methodologies employed are still carried out in a destructive, laborious way, using high cost equipment, demanding a lot of time in the analysis, space and resources. The objectives of this work were: i) to study the genetic divergence of the green leaf color intensity in C. canephora genotypes, and ii) to relate the intensity of leaf green coloration with photosynthetic performance in C. canephora genotypes, as a way to potentiate large-scale phenotyping of individuals with superior photosynthetic capacity. 40 genotypes of C. canephora cultivated under field conditions were initially evaluated. With the aid of a portable chlorophyll meter, it was estimated in leaves, in a non-destructive way, total chlorophyll indices, flavonoids, anthocyanins and nitrogen balance. The specific and unitary leaf areas were also determined. From the results obtained, a significant differences were found between the genotypes for the evaluated characteristics, except for specific leaf area. The genotypes were arranged in four distinct groups based on genetic distances. The total chlorophyll index showed the greatest contribution to genetic divergence. The relationship between the intensity of green leaf color and photosynthetic performance was studied in the six most divergent genotypes. For this, it was determined in the field, in a non-destructive way, using portable chlorophyll meters, the pigment indexes. Leaf transmittance and electron transport rate were also determined on the same leaves. Subsequently, the leaves were collected to determine the concentration of photosynthetic pigments, total soluble phenols, nitrogen, phosphorus and specific leaf area. The intensity of the green leaf color, determined in a non-destructive way with portable chlorophyll meters, showed a significant relationship with the concentration of pigments, nitrogen and leaf transmittance. In C. canephora, the use of portable chlorophyll meters can be used as a tool for the selection of genotypes that present superior photosynthetic performance.