Genetic Diversity Based on Nutrient Concentrations in Different Organs of Robusta Coffee

Abstract

The objective of this study was to evaluate nutrient concentrations in the flowers, leaves (pre-flowering and grain-filling period), grains, and husks of Robusta coffee genotypes cultivated in the Amazon region, as well as to identify their genetic diversity. This experiment was carried out in Alta Floresta D’Oeste, Rondônia, Brazil, in randomized blocks with three replications; for the leaves, a factorial experimental design of sampling periods was included. The nutrient concentrations of the different evaluated organs were subjected to analysis of variance by the F test (p < 0.01), and the genetic parameters were estimated. To determine the genetic diversity, the genotypes were grouped by the UPGMA hierarchical method, and to predict it the relative importance of traits was analyzed. Genetic divergence among Coffea canephora genotypes was indicated by the leaf nutrient concentrations. At a maximum dissimilarity threshold of 82% for the genotypes, the UPGMA method formed six groups. Concentrations of nitrogen (N) and phosphorus (P) in the leaf sampling periods of pre-flowering and grain filling were not influenced by genotypes. The leaf and flower iron (Fe) concentrations contributed most to genetic divergence. For a nutritional diagnosis of Robusta coffee, it is important to take into account the comparisons of genetic diversity as well as the nutritional requirements during the flowering and grain-filling periods.

Nutritional Balance and Genetic Diversity of Coffea canephora Genotypes

“…Significant differences in the grain and husk nutrient concentrations between C. canephora genotypes cv. Robusta were also reported by [ 4 ] and in leaf concentrations by [ 15 ]. The variation in the different organs may be associated with the genotype-specific requirements throughout the cycle, nutrient uptake, mobility in the conductive vessels and distribution of the root system [ 21 ].…”

“…To increase the reliability of the dissimilarity among the grouped genotypes, the Tocher method has also been used. In the studies conducted by [ 4 , 36 , 37 , 38 , 39 ], the similarity and consistency of the methods in the formation of groups of C. canehora genotypes has been confirmed.…”

“…Evaluation studies conducted by [ 4 , 8 , 13 , 15 ] with nutrient concentrations in different organs (leaf, flowers, grains, husk, fruits) of conilon coffee also reported values higher than 20% for some nutrients. Factors such as size of the experiment, maturation cycle and genotype response to biotic and abiotic factors may have contributed to the high indices [ 14 ].…”

“…The nutrients Ca, Mg, Cu and Mn exceeded 80% in the grain and the husk. For heritability (H 2 ), indices above 80% are considered highly relevant for breeding, since the trait expresses the confidence degree of the phenotypic value, which is a favorable genetic indicator for selection [ 4 , 18 ]. In an evaluation of nutrient concentrations in flowers, leaves, grains and husks in Robustas Amazônicos, [ 4 ] also found values above 80% for some nutrients.…”

“…As a crop with a high yield potential, which accumulates large nutrient amounts in the vegetative and reproductive tissues, coffee requires high levels of nutrient supply [ 4 ]. Consequently, the nutritional management has to ensure a balance between the amount of supplied nutrients and those removed in the harvested fruits.…”