Development of clonal seedlings of promising Conilon coffee (Coffea canephora) genotypes

Abstract

Conilon coffee is a highly heterozygous diploid plant that is also allogamous, producing seeds through cross-fertilisation. Due to their allogamy, plants of seminiferous origin are highly heterogeneous, exhibiting high morphological and genetic diversity. However, propagation through cutting guarantees the maximum homogeneity of fields, particularly in grain maturation, among other desirable characteristics. Currently, the majority of commercial Conilon coffee is planted using seedlings propagated by cuttings. Studying the juvenile behaviour of different clonal genotypes of the Conilon coffee plant represents an important tool to assist with the establishment of this crop. The objective of this study was to assess the growth, development and genetic diversit y in several promising genotypes of the Conilon coffee plant based on the morphological characteristics of seedlings propagated by cutting. We used seedlings Conilon coffee of 33 genotypes selected by coffee growers, and with great productive potential, and genotype 02 of the Emcapa 8111 variety. Based on morphological characteristics linked to the growth and development of the aboveground and root systems of the genotypes, their phenotypic correlations were estimated, along with the genetic diversity among genotypes, using Tocher's optimisation method and the unweighted peer group method with arithmetic mean. Genotypes A1, P2, Z39, Ouro Negro, Tardio C, Cheique, and Z29 exhibited a higher Dickson quality index (between 0.40 and 0.56). Genetic variability exists among the seedlings of the 34 genotypes of Conilon coffee studied. The most dissimilar genotypes were CHR, 18, and Z39, which remained in isolated groups in all experiments.Keywords: Coffea canephora; Genetic diversity; Variability; Vegetative propagation; Phenotypic correlation. Abbreviations: ADM_aboveground dry matter; ANA_National Water Agency; CONAB_National Food Supply Agency; DAPC_days after planting by cutting DQI_Dickson quality index; EMS_etiolation of the main stem; ICO_International Coffee Organization; LA_leaf area; LDM_leaf dry matter; LLR_length of largest root; MAPA_Brazilian Ministry of Agriculture; NIPS_number of internodes on the primary stem; NISS_number of internodes on the secondary stem; NOS_number of orthotropic shoots; NPR_number of primary roots; NPTB_number of plagiotropic branches; PSBD_primary stem base diameter; PSH_primary stem height; RDM_root dry matter; RV_root volume; SDM_stem dry matter; SLM_specific leaf mass; SSBD_secondary stem base diameter; SSH_secondary stem height; TDM_total dry matter; and UPGMA_hierarchical unweighted pair group method with arithmetic mean.

Genetic diversity of promising ‘conilon’ coffee clones based on morpho-agronomic variables

“…The groups formed by the UPGMA method, assuming a maximum dissimilarity limit of 50% among the genotypes, were formed similarly to those generated by Tocher's method, increasing the consistency between the clustering methods. Similarities between Tocher's and UPGMA hierarchical method were also observed by Ivoglo et al (2008), Guedes et al (2013), andCovre et al (2016), who established the maximum limits of dissimilarity among genotypes as 15%, 45%, and 50%, respectively Except for genotypes 30 and 10, all the others that represented the most dissimilar parents based on the generalized Mahalanobis distance (D 2 ) (Table III) were allocated in distinct groups by both Tocher's optimization (Table IV) and the UPGMA hierarchical method (Figure 1), increasing the reliability in the use of clusters to establish divergent combinations. Motta et al (2014) evaluated C. arabica and C. canephora genotypes and also observed that the most dissimilar genotypes based on Jaccard's index were mostly allocated in distinct groups by UPGMA.…”

“…Studies reporting the use of Tocher's method for clustering C. canephora genotypes were also conducted by Fonseca et al (2006), who worked with 32 clones of three clonal varieties; by Ivoglo et al (2008), with 21 progenies of half-siblings; and by Covre et al (2016), with 34 promising genotypes, who reported the formation of three, four, and eight groups, respectively.…”

“…Studies on the genetic diversity of coffee adopting multivariate analyses have been carried out by many researchers, both for C. canephora (Fonseca et al 2006, Ivoglo et al 2008, Dalcomo et al 2015, Silva et al 2015, Covre et al 2016), and C. arabica (Dias et al 2005, Guedes et al 2013, Moura et al 2015, Rodrigues et al 2016. Information in this regard provides bases to be used in breeding programs for the species.…”

Research Article Equations for estimation of the foliar area of Coffea canephora genotypes

“…The genotypes were divided into three groups, with 41 genotypes in group 1, and the other two groups were composed of genotypes 2 and 4, respectively. The Tocher clustering method was employed by Fonseca et al (2006) when evaluating 32 clones constituting three clonal varieties forming three groups; also by Ivoglo et al (2008) with 21 progenies of half-brothers divided into four groups; and by Covre et al (2016) and Giles et al (2018) with 34 and 30 promising genotypes, in which they obtained eight and three groups, respectively.…”

“…A study by Partelli et al (2006) proposed an equation model for conilon coffee (C. canephora) considering the length of the central vein, generating two equations according to the age of the plant, be it young or mature. However, due to the great genetic variability in C. canephora (Covre et al, 2016;Espindula et al, 2018) the plants from a specific population are heterogeneous and have distinct characteristics, and as such the revalidation of these methods becomes necessary after some time. However, the wide availability of new genotypes and their numerous distinct morphological characteristics can change the precision of the methods based on the leaf area of older genotypes (Brinate et al, 2015ab).…”