Coffee breeding based on root traits is important to identify productive genotypes under adverse environmental conditions. This study assessed the diversity of root traits in Coffea canephora and its correlation with plant height and crop yield. Undisturbed soil samples were collected down to 60 cm from 43 coffee genotypes, in which one of them was propagated by seed and all others by stem cutting. The roots were washed, scanned, and processed to quantify root length density, root volume, root superficial area, and root diameter. Additionally, plant height and crop yield were also assessed. Root length density ranged from 40 to 1411 mm cm⁻³, root volume from 6 to 443 mm³ cm⁻³, root superficial area from 61 to 1880 mm² cm⁻³, and root diameter from 0.6 to 1.1 mm. Roots were concentrated in the topsoil (0–20 cm) for most genotypes. In deeper depths (30–60 cm), root length density, root volume, and root superficial area were higher in genotypes 14, 25, 31, and 32. Positive correlations were found between root traits and both plant height and crop yield. The results of this work may contribute to the overall cultivation of C. canephora, specially for crop breeding in adverse environmental conditions.

Coffee genotypes cultivated in the Amazonian region have been gaining increasing prominence in Brazilian plantations. This study aimed to quantify nutrient accumulation in the fruits, grains, and husks of Robusta coffee genotypes cultivated in the Brazilian Amazon and estimate genetic diversity. The experiment was conducted in Alta Floresta D’Oeste—Rondônia, Brazil. To assess nutrient accumulation, fresh fruits were collected. These were dried, processed, separated into grains and husks, and subjected to chemical analysis. Nutrient accumulation in fruits, grains, and husks, as well as the grain/husk ratio, underwent analysis of variance through the F-test (p < 0.01. For each evaluated trait, the experimental coefficient of 337 variation (CVe), genetic coefficient of variation (CVg), and genotypic determination coefficient (H²) were also estimated. Variability was observed among Robusta coffee genotypes, with VP06, AS4, and AS10 being the most dissimilar. LB080 had the lowest dry fruit weight and the lowest percentage of grains in relation to husks. ZD156 accumulated more K in the grains, while VP06 and AS10 were the genotypes that accumulated more nutrients in the husks. Nutrients N, K, Ca, and P are accumulated in larger quantities, necessitating the calibration of mineral fertilization dosages and distribution.

This work aimed to evaluate the variability in the distribution of the root system among genotypes of C. canephora cv. Conilon and indicate management strategies for a more efficient mineral fertilization. Root distribution was evaluated in six genotypes. The experimental design was in randomized blocks with three replications. Soil monoliths measuring about 27 cm³ were collected at six different soil depths, at three row distances and nine distances of inter-row planting. The collections were carried out in one plant of each repetition. In total, 1296 samples were evaluated. The roots were washed, digitized and processed to quantify length density, volume, surface area and diameter. The distribution of the root system was characterized using semivariograms. It was observed that the highest concentration of roots occurred in the distances close to the irrigation drippers. There was variation in the distribution of the root system among the genotypes. However, in general, the root system is concentrated at a depth of 0 to 20 cm in the soil, at distances up to 50 cm in the planting row and up to 60 cm in inter-rows. Therefore, the greatest efficiency in nutritional management can be achieved by applying fertilizers within a radius of 50 cm around the plant.

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.

In Coffea canephora, the number of orthotropic shoots is directly related to plant yield. The objective of this study was to evaluate the vegetative and yield performance of Coffea canephora, from the botanical variety Conilon, under different management systems for early emission of orthotropic shoots. The experiment was carried out in Ouro Preto do Oeste, Rondônia, between November 2011 and May 2014. Three types of management techniques were tested for early induction of orthotropic shoots in coffee trees (T1 = bending of the orthotropic shoot; T2 = apical pruning of the orthotropic shoot, T3 = free growing). The experiment was conducted in a randomized block design with 20 replicates. Each block consisted of a clonal genotype (clone) from the Embrapa Coffee Breeding Program. The techniques pruning and apical pruning were efficient to induce early growth of orthotropic shoots in Coffea canephora, resulting in higher yield in the first commercial bean production.

The objective of this work was to determine the contribution of the number of stems to the composition of individual plant yield, and to individual and overall robusta coffee (Coffea canephora) yield at different planting densities, using a fixed number of stems per plant. The experiment was carried out in two phases. The first phase was performed from 2011 to 2015, in the municipality of Ouro Preto do Oeste, in the state of Rondônia (RO), Brazil, to evaluate different numbers of stems per plant (1, 2, 3, 4, 5, and 6). The second phase was conducted from 2013 to 2018, in the municipality of Alta Floresta D’Oeste, RO, to evaluate plant densities (at 1,666, 1,904, 2,222, 2,666, and 3,333 plants ha-1), with an initial density of four stems per plant in all treatments. The increase of number of stems per plant promotes a quadratic response to the average and cumulated yield of coffee plants, and the maximum yield is attained with four stems per plant. The number of stems should not exceed four, to avoid their tipping during years of high production. Plant density of 3,333 plants per hectare, with 4 stems per plant and 1 m spacing, promotes the reduction of individual plant yield; however, it results in higher overall crop yield.