Genetic diversity among 16 genotypes of Coffea arabica in the Brazilian cerrado.

For the selection of coffee plants that have favorable characteristics, it is necessary to evaluate variables related to production. Knowledge of the genetic divergence of arabica coffee is of extreme importance, as this knowledge can be associated with plant breeding programs in order to combine genetic divergence with good productive performance. The objective of this study was to evaluate the genetic divergence among 16 genotypes of Coffea arabica with the purpose of identifying the most dissimilar genotypes for the establishment of breeding programs and adaptation to the Brazilian cerrado. The genetic divergence was evaluated using multivariate procedures, the analysis of the average grouping unweighted pair group method with arithmetic mean (UPGMA) and main components in 2013 and 2014. Eight characters were evaluated in an experiment conducted in Morrinhos, Goiás. The presence of genetic divergence among the 16 C. arabica genotypes under cerrado conditions was recorded. The formation of UPGMA groups for the evaluated characteristics was pertinent due to the number of genotypes. The first three major components accounted for 81.77% of the total variance. The genotype H-419-3-4-4-13(C-241) of low size was the most divergent, followed by Catucaí 2 SL and Catiguá MG2, according to the main components.

Genetic diversity of standard leaf nutrients in Coffea canephora genotypes during phenological phases.

Diagnosing foliar nutritional status is essential for fertilizer recommendations and for the identification of nutrient imbalances. This study aimed to verify genetic diversity and establish mean standards (leaf nutrient contents; LNCs) and relationships among leaf nutrients (LNC relationships; LNCRs) in seven conilon coffee genotypes during both pre-flowering and bean-filling stages. Twenty crops from several cities in the northern region of Espírito Santo State, Brazil, with crop yield either equal to or greater than 100 bags per hectare (during two harvests) were assessed. A total of 140 samples were collected during each evaluation period for quantification of leaf nutrient contents (N, P, K, Ca, Mg, S, Fe, Zn, Cu, Mn, and B). The Ward procedure, a hierarchical genetic clustering method, was used to quantify the genetic diversity among genotypes. To examine differences between the LNCs and LNCRs, F-and Scott-Knott tests were used. LNCs and LNCRs showed significant differences among the conilon coffee genotypes during the evaluation periods. Additionally, the 8V, 10V,and 12V genotypes exhibited the highest values for most of the nutrients, especially for N, P, and Cu. Therefore, the clustering method revealed genetic diversity among genotypes for standard leaf nutrient levels, implying that leaf diagnosis could be specific to each genotype and phenological stage.

Assessment of genetic divergence among coffee genotypes by Ward-MLM procedure in association with mixed models.

Mixed linear models have been used for the analysis of the genetic diversity and provided further accurate results in crops such as eucalyptus, castor, and sugarcane. However, to date, research that combined this analysis with Ward-MLM procedure has not been reported. Therefore, the aim of the present study was to identify divergent coffee genotypes by Ward-MLM procedure, in association with the mixed-decision models. The experiment was initiated in February 2007, in the northwestern Rio de Janeiro State. The 25 evaluated genotypes were grown with a spacing of 2.5 x 0.8 m, in a randomized block design, with 5 replications, containing 8 plants each. The following agronomic traits were evaluated: plant height, stem diameter, plagiotropic branch number, and productivity. Four measurements were performed for each character from 2009 to 2012, between May and July. Data were analyzed using REML/BLUP analysis and Ward- MLM procedure. The Ward-MLM procedure in association with mixed linear models demonstrated the genetic variability among the studied coffee genotypes. We identified two groups of most divergent coffee genotypes, which can be combined by crossings and selections in order to obtain genotypes with high productivity and variability.

Evaluation of genetic divergence among clones of conilon coffee after scheduled cycle pruning.

Coffea canephora genotypes from the breeding program of Instituto Capixaba de Pesquisa e Extensão Rural were evaluated, and genetic diversity was estimated with the aim of future improvement strategies. From an initial group of 55 genotypes, 18 from the region of Castelo, ES, were selected, and three clones of the cultivars "Vitória" and "robusta tropical." Upon completion of the scheduled cycle pruning, 17 morphoagronomic traits were measured in the 22 genotypes selected. The principal components method was used to evaluate the contributions relative to the traits. The genetic dissimilarity matrix was obtained through Mahalanobis generalized distance, and genotypes were grouped using the hierarchical method based on the mean of the distances. The most promising clones of Avaliação Castelo were AC02, AC03, AC12, AC13, AC22, AC24, AC26, AC27, AC28, AC29, AC30, AC35, AC36, AC37, AC39, AC40, AC43, and AC46. These methods detected high genetic variability, grouping, by similarity, the genotypes in five groups. The trait that contributed the least to genetic divergence was the number of leaves in plagiotropic branches; however, this was not eliminated, because discarding it altered the groups. There are superior genotypes with potential for use in the next stages of the breeding program, aimed at both the composition of clonal variety and hybridizations.

Evaluation of castor bean genotypes sown in winter and summer at a low altitude.

Current demands for the genetic breeding of castor bean include the adaptation of genotypes to low altitudes to expand the potential areas of cultivation. This study was conducted to evaluate the response of different genotypes of castor bean that were sown in winter and summer at a low altitude. The study was conducted in northwestern Rio de Janeiro State at an altitude of 60 m. The treatments consisted of genotypes IAC 80, AL Guarany 2002, BRS 149 Nordestina, BRS 188 Paraguaçu, Savana, Lyra, Mirante 10, IAC 226, Cafelista, G1, V1, and T1 with spaces of 2.0 m between rows, 1.0 m between plants, and one plant per hole. The plant height, number and length of racemes, number of fruits per raceme, seed yield, and incidence of gray mold were determined. The highest yields in both seasons were obtained by the genotypes BRS 149 Nordestina, G1, BRS 188 Paraguaçu, and IAC 226. The genotypes Savannah and Lyra had the lowest yields in both cultivation seasons. The genotypes responded differently to the environmental conditions depending on the growing season, and the spring-summer period was found to be more favorable at the low altitude of the study site.

Adaptability and stability of conilon coffee in areas of high altitude.

In view of the predicted models of global climate change and differences in prices and production costs, there is increased interest in Coffea canephora cultivation in areas of high altitude. However, this species is sensitive to low temperatures, where genotypes vary regarding adaptation/tolerance mechanisms, demonstrating genotype x environment interaction. The aim of this study was to evaluate the stability and adaptability of C. canephora varieties in high-altitude areas. The experiments were carried out in February 2004, in Bom Jesus do Itabapoana, Rio de Janeiro State, Brazil, at an altitude of 725 m. Four clonal varieties (EMCAPA 8111, EMCAPA 8121, EMCAPA 8131, and EMCAPA 8151) and five harvests (2006 to 2010) were used. The experimental design was randomized blocks with four treatments and six plots, with 12 plants in each plot and spaced 2.5 x 1.2 m. Adaptability and stability parameters were determined using methods based on nonparametric analysis and analysis of variance. The results showed that the EMCAPA 8131 had the best performance according to stability and adaptability parameters and may be promising for high-altitude regions.

Agronomic performance of arabica coffee genotypes in northwest Rio de Janeiro State.

Considering the productive potential of arabica coffee in the Rio de Janeiro State and the shortage of breeding programs for this species in the state, this study aimed to evaluate the vegetative and productive characteristics of 25 arabica coffee genotypes to indicate 1 or more varieties for the northwest Rio de Janeiro region. The experiment was in Varre e Sai, RJ, Brazil, and plants were planted in 2007 with a spacing of 2.5 x 0.8 m. Five plots were used, consisting of 8 plants per plot to measure vegetative growth, height, stem diameter, and plagiotropic branch number characteristics and productivity in the biennia 2009/2010 and 2011/2012. The classification by sieve was performed at harvest in 2011. The variables were subjected to analysis of variance and means grouped by the Scott Knott test at 5% probability, and the productivity was subjected to joint analysis of variance. Pearson's correlation coefficients between growth and productivity variables were estimated. The best genotypes were Catucaí Amarelo 2 SL, Catiguá MG 02, Acauã, Palma II, Sabiá 398, IPR 103, IPR 100, Catucaí Amarelo 24/137, and Catucaí Amarelo 20/15.