SEASONAL-VARIATION IN BORON CONTENT OF COFFEE COFFEA-ARABICA L CV CATUAI

The boron contents of the second, third and fourth pairs of leaves of coffee cv. Catuai were measured from January to December 1990 on the Coffee Research Centre farm (CICAFE) situated at Barva de Heredia, Costa Rica. Seasonal variation curves were produced in relation to leaf age to define the evolution of boron content throughout the year. Boron contents varied between leaf pairs and were closely related to age, the differences being more marked during periods of high rainfall. The curves of leaf boron content showed similarities but differed in relation to the time of year. The boron content decreased under drought conditions, increased with the onset of the rains and again decreased as the rainfall became more abundant.