Potencial matricial da água no solo em cultura de seringueira (>i<Hevea brasiliensis>/i< Muell. Arg.)

Abstract

The study was conducted in a rubber tree (Hevea brasiliensis Muell. Arg.) plantation plot of the clone IAN 3087 with the objetive of investigating the pattern of soil matric potential in relation to the distance from the tree trunk.. The study area was located in Piracicaba, SP, Brasil (latitude 22° 43' S, longitude 47°38' W and altitude 576 m), on a "terra roxa estruturada" soil.Matric soil water potential was determined using mercury manometer tensiometers localized at regular distances from the trunk, in two directions: between rows and between trees in the row. Toe root system was sampled by augers, according to tensiometers localizations.The lowest values of matric potential occured at the di stances 1. 25 m and O. 625 m from the trunk. between rows. As far as 2.5 m from the trunk the matric potential did not change significantly. ln the tree row, the values viii.were more negative at the middle of the distance between the trees than at 0.54 m from the trunk. Low values were observed at depths shallower than 37. 5 cm and at depths below 112. 5 cm.Toe sampling of the root system showed that up to 1.6 m from the tree trunk and in the soil layer O to 30 cm, 54.08% of the total sampled root system was present. As far as 2.2 m from the tree trunk the root density was very low. ln the tree row the highest densi ty was in the soil layer O to 30 cm. ln general, matric potential distributions reflected root densi ty dis. tributions and the information is useful for rubber tree crop management practices. * * tensiômetro com coluna quebrada.