Synchronization of anthesis and enhancement of vegetative growth in coffee (Coffea arabica L.) following water stress during floral initiation

Abstract

The possibility of using water stress during floral initiation and development, to synchronize flowering in potted coffee trees of cvs Catuai Rojo and Mundo Novo was investigated. Moderate and severe cyclic and constant water stress had little effect on vegetative growth during floral initiation. However, upon rewatering, shoot growth was significantly greater in plants where leaf water potential [?,] had declined to -2.5 MPa compared with plants where ?, was maintained above -0.5 MPa. The period of floral initiation was not influenced by water stress and occurred only under short days (<12 h). In contrast, a y, of -2.5 MPa significantly reduced the number of inflorescences compared with plants maintained at a ?| of -0.5 or -1.5 MPa. This reduction was associated with leaf drop in stressed plants. Therefore, regular irrigation during the period of floral initiation is recommended. Water stress (?, of -1.5 or -2.5 MPa compared with -0.5 MPa) accelerated floral development with no deleterious effects on floral differentiation. Once flower buds are fully differentiated they enter dormancy and reach anthesis only if trees are stressed and rewa-tered. Flower buds remain dormant if trees are watered regularly or a constant water stress provided. A constant period of water stress in the late stages 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 irrigation and a reliable dry season in the late stages of floral development.