Procedimento para a medição do potencial hídrico foliar em cafeeiro usando psicrômetro de termopar

Abstract

Introduction: The thermocouple psychrometer (WP4-T) is an equipment that can be used to measure leaf water potential (PHF). According to the methodology suggested by the manufacturer to measure PHF, the abaxial surface of the leaf must be sanded, aiming to remove the cuticle and expose the stomata. In addition, there is evidence that synthetic or plant covers on the ground can influence PHFs Objective: So, the objective of this work was to verify the influence of the sanding procedure and the effect of the ground cover on the PHF readings. Methods: Coffee leaves were collected in an experimental area containing three treatments, namely: ground cover in the coffee tree line with white plastic (Pb); ground cover in the row with remains of brachiaria from periodic cuts between the rows (Bq), and ground cover in the row with remains of weeds from between the rows that are periodically mowed – (Pe). PHF data were submitted to statistical analysis and means were compared using the Scott-Knott test (5%). Results: The time to obtain readings of leaf water potentials in WP4-T is reduced when the abaxial faces of the leaves receive the sanding procedure. The abrasive procedure with sandpaper favors obtaining greater leaf water potentials. The management of coffee crop lines with plastic cover or plant residues from brachiaria between the lines favored the highest values of leaf water potential. Therefore, these covers can be alternatives for coffee growers to minimize the effects on coffee crops of soil water deficit. Conclusion: The sanded leaves had higher PHF values and it was found that the Pb and Bq treatments provided higher PHF readings, which is probably related to the greater permanence of water in the soil in these managements.