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Abstract The objective of this work was to quantify the genetic diversity and selection gains regarding the physical traits of the fruits and beans of the 86 Coffea canephora clones most grown in western Amazon. The clones were evaluated as to the effects of genotypes (G), years (Y), and the GxY interaction. Genetic progress was quantified considering combined selection and direct selection for coffee bean weight. Although there was a GxY interaction, based on repeatability estimates the plants presented a similar performance over time. A positive correlation was observed between fruit and bean weight, except for some genotypes, such as R22, AS5, and 'BRS 3210', which presented larger beans and smaller fruit, and as BG180, P42, LB60, G20, and N12, with larger fruit and smaller beans. Using selection for the main trait, the estimates of genetic progress were similar to those obtained through different selection indexes, through which 14 genotypes with a higher bean weight were selected. The evaluated C. canephora clones exhibit high genetic diversity for the selection of plants with higher grain mass.

ABSTRACT: With advancements in coffee cultivation, several traits may be considered in selection of plants, which must exhibit a set of favorable characteristics. The outturn index, defined as the relationship between the mass of mature fruit and processed beans, emerges as a key factor influencing productivity. This study characterized the outturn over two harvests of 57 clones marketed in the public domain and 10 registered cultivars. The analysis considers the effects of genotypes, measurements, and genetic progress achieved through plant selection. According to the maturation cycle of each clone, washed samples of cherry coffee were collected considering a completely randomized factorial design for characterization of the effects of genotypes, years, and the genotype × years (GY) interaction. The drying, peeling, and the outturn index were individually assessed. Despite the significant effects of the GY interaction, genotypes demonstrated minimal alterations in their ranking across measurements. Clones with higher outturn, including LB30, BRS1216, LB12, N7, LB10, LB20, BRS3220, and AS5, exhibited an average outturn of 25.51%, reflecting a gain of 12.17%. Conversely, clones with lower outturn, such as BG180, GJ30, GJ20, AS7, AS10, P42, N1, and P60, had an average of 19.15%, indicating a reduction of 14.02% compared to the general mean. Analyzing the distribution of the outturn values, 19.4%, 62.7%, and 17.9% of genotypes were classified as high, medium, and low outturn, respectively, providing valuable insights for optimal cultivation strategies.

In nature, the ability to avoid self-fertilization has evolved to prevent the deleterious effects of inbreeding. However, under cultivation conditions, self-incompatibility can reduce the pollination efficiency of Coffea canephora. The objective of this study was to characterize the self-incompatibility expression of the most cultivated genotypes in Western Amazonia, to improve the management of this coffee plant. In vitro pollinations were conducted among 45 genotypes, and the development of pollen tubes was evaluated using fluorescence microscopy. Pollination efficiency was evaluated considering the allelic variability within a breeding population from an ideal condition of maximum genetic variability. Based on the compatibility response, the genotypes were organized into six groups: group I (24.4%), group II (31.1%), group III (24.4%), group IV (2.2%), group V (2.2%), and group VI (15.6%). The lower frequencies of groups IV, V, and VI were associated with the lower frequency of the rarest allelic forms in this breeding population (p = 0.36, q = 0.26, r = 0.29, and s = 0.10). The correspondence between allelic and genotypic frequencies indicates that this population is in Hardy–Weinberg equilibrium (HWE) for this trait. Considering the cultivation of 2 to 10 clones, the population studied showed intermediate pollination efficiency between an ideal HWE population with p = q = r = s = 0.25 and a population with the rarest allelic forms (p = 0.48, q = 0.32, r = 0.19, s = 0.01). Efficiency estimates were stabilized from the cultivation of five clones, indicating that cultivating a minimum number of clones should be considered. Theoretically, maximum pollination efficiency is achieved by representing all alleles in equal proportions, whereas in practice, farmers should ensure the cultivation of plants from different compatibility groups, without significant imbalances.