Vol. 8(34), pp. 4422-4426, 5 September, 2013 DOI:10.5897/AJAR12.1999 ISSN 1991-637X ©2013 Academic Journals http://www.academicjournals.org/AJAR African Journal of Agricultural Research Full Length Research Paper Crop yield bienniality in groups of genotypes of conilon coffee Wagner Nunes Rodrigues 1 *, Marcelo Antonio Tomaz 2 , Romário Gava Ferrão 3 , Maria Amélia Gava Ferrão 4 , Aymbiré Francisco Almeida da Fonseca 4 and Lima Deleon Martins 1 1 Programa de Pós-Graduação em Produção Vegetal, Centro de Ciências Agrárias da Universidade Federal do Espírito Santo, CCA-UFES, Alto Universitário, Cx. P. 16, CEP: 29500-000, Alegre, Espírito Santo, Brazil. 2 Departamento de Produção Vegetal, Centro de Ciências Agrárias da Universidade Federal do Espírito Santo, CCA-UFES, Alto Universitário, Cx. P. 16, CEP: 29500-000, Alegre, Espírito Santo, Brazil. 3 Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural, INCAPER, Rua Afonso Sarlo, 160, Bento Fereira, CEP: 29052-010, Vitória, Espírito Santo, Brazil. 4 Empresa Brasileira de Pesquisa Agropecuária, EMBRAPA CAFÉ/INCAPER, Parque Estação Biológica, PqEB, s/n, CEP: 70770-901, Brasília, Brazil. Accepted 21 August, 2013 Coffee plantations present large spatial and temporal variability of yield, the variation along the years with high and low productions is known as bienniality. This study investigated the bienniality in different groups of genotypes of conilon coffee, classified by the ripening cycle, evaluating the crop yield of the clones along four years to determine the magnitude of the bienniality. The results indicate that, the bienniality is present in genotypes of conilon coffee from all the studied groups of genotypes, existing very biennial genotypes and also very stable genotypes within each group. Key words: Coffea canephora, crop yield, stability. INTRODUCTION Coffee is one of the most valuable traded commodities in the world. The species Coffea canephora is the most widely grown in the State of Espírito Santo. In addition, this state is the largest Brazilian producer of conilon coffee, with approximately an estimated production of 9.25 000 000 bags for 2013. The coffee park in Espírito Santo covers an area of approximately 280 000 ha in current production, with an average crop yield of 34.68 bags per hectare (Conab, 2013). A large spatial and temporal variability occurs in the crop yield of coffee plantations, being common in the occurrence of plants with low production alongside with highly productive plants. The temporal variability, such as the bienniality, results in years with high yield intercalated with years of low production (Carvalho et al., 2004). The bienniality is a phenomenon more pronounced in the species C. arabica, but it is also present in C. canephora, usually less intense due its mitigation with the pruning practices and alternation of the plagiotropic branches in production. This biennial alternation of yield is the result of the physiological nature of the coffee plant, which needs to vegetate along a year to sustain the fruit production in the next year (Rena and Maestri, 1985). The occurrence of bienniality in coffee plants is connected to a source-sink relationship existing between fruit and leaves. Leaves are sources of photosynthates while the growing tissues act as sinks. As both of the reproductive and vegetative growths occur simultaneously, *Corresponding author. E-mail: wagnernunes86@hotmail.com, lima_deleon@hotmail.com. Tel: +552835528998.