Induction and differentiation of reproductive buds in Coffea arabica L.

Abstract

The induction and differentiation phases of reproductive buds of Coffea arabica L. have not received much attention. In the present paper, axillary buds from five plagiotropic branches that developed in the same growing season without fruits (1st crop branches), and from green segments of five recently grown plagiotropic branches with fruits (2nd crop branches), were collected every two weeks during successive inductive months of the year. This study was carried out with adult arabica trees, Catuaí Vermelho cv. IAC 81, cultivated under normal farming conditions in the region of Campinas, SP, Brazil (22º54' Lat. S). Slides of longitudinal-axial sections of 10-12 mum thickness were mounted for the characterization and quantification of histological stages of bud differentiation. The results indicate that the regulatory signals controlling the phases of induction and differentiation of floral buds are distinct, and that there are differences in the response between branches with and without fruits. In the case of 1st crop branches (no fruits present), induction of floral buds took place in January and February, whereas floral bud differentiation was observed during the months of March and April. In 2nd crop branches (fruits present), the induction of floral buds was observed during any month of the year provided that they had already overcome their juvenile state (October-July, in this study). In these 2nd crop branches, the flower bud differentiation was only observed after harvesting all pre-existing fruits of each branch (after May, in this study), which suggests that floral bud differentiation in Arabica coffee is influenced by the source-sink relationship, i.e. by the presence of developing fruits within each plagiotropic branch.

A functional role for the colleters of coffee flowers

“…The formation of flower primordia occurs in March/April (Majerowicz and Söndahl 2005). Starting in May, the temperature and rain precipitation decline and remain low compared with other months until August/September.…”

Variations in leaf growth parameters within the tree structure of adult Coffea arabica in relation to seasonal growth, water availability and air carbon dioxide concentration

“…A coffee metamer is composed of an internode, two leaves and 4-5 buds, which are present in a linear sequence in axil of each of two leaves in a pair (Majerowicz and Söndahl, 2005). The most developed bud of this series can originate a new lateral branch or an inflorescence.…”

Drought and re-watering modify ethylene production and sensitivity, and are associated with coffee anthesis

“…Coffee's asynchronous flowering pattern results from asynchronies in bud development along the branches at the vegetative and reproductive levels (Majerowicz & Söndahl 2005;de Oliveira, Cesarino, Mazzafera & Dornelas 2014) . In addition, environmental factors are also important, since a period of water deficit may stimulate anthesis, and low intensity rainfall events during the dry season, which often occurs before the wet season starts, can contribute to multiple flowering events (Guerra et al 2005;da Silva, Brunini, Sakai, Arruda & Pires 2009).…”