SYNCHRONIZATION OF ANTHESIS AND ENHANCEMENT OF VEGETATIVE GROWTH IN COFFEE (COFFEA-ARABICA L) FOLLOWING WATER-STRESS DURING FLORA INITIATION

The possibility of using water stress during floral initiation and dev elopment, to synchronize flowering in potted coffee trees of cvs Catua i Rojo and Mundo Novo was investigated. Moderate and severe cyclic and constant water stress had little effect on vegetative growth during f loral initiation. However, upon rewatering, shoot growth was significa ntly greater in plants where leaf water potential [psi(l)] had decline d to -2.5 MPa compared with plants where psi(l) was maintained above - 0.5 MPa. The period of floral initiation was not influenced by water s tress and occurred only under short days (< 12 h). In contrast, a psi( l), of -2.5 MPa significantly reduced the number of inflorescences com pared with plants maintained at a psi(l) of -0.5 or -1.5 MPa. This red uction was associated with leaf drop in stressed plants. Therefore, re gular irrigation during the period of floral initiation is recommended . Water stress (psi(l) of -1.5 or -2.5 MPa compared with -0.5 MPa) acc elerated floral development with no deleterious effects on floral diff erentiation. Once flower buds are fully differentiated they enter dorm ancy and reach anthesis only if trees are stressed and rewatered. Flow er buds remain dormant if trees are watered regularly or a constant wa ter stress provided. A constant period of water stress in the late sta ges of floral development after floral initiation is complete provides a means of increasing the proportion of fully differentiated dormant flower buds (mature buds). This could represent a practical method to achieve synchronized flowering in field conditions where there is irri gation and a reliable dry season in the late stages of floral developm ent.