Propiedades Físicas e Hidráulicas de Perlita en Cultivos de Rosas y sus Variaciones Temporales

Abstract

Physical and hydraulic properties of perlite used as unique substrate in a greenhouse cut roses (Rosa hybrida L.) culture and their dependence on time were investigated. Samples of, perlite with 0,28 and 39 months of use, extracted from the rhizosphere, were analyzed. Bulk density (DA), real density of intact particles (DRI) real density of pulverized particles (DRP), particle size distribution, air capacity (CA), available water (AFD), unavailable water (AR) and effective porosity (PE) were determined. Non-saturated hydraulic conductivity (Kns) was obtained using the Mualem van Genuchten model. It was found cracking of particles with diameters greater than 2 mm and an increment of the fraction between 1 mm and 2 mm after 28 and 39 months of use. No significant alteration of particles with diameters smaller than 0,5 mm was found. Values of PE and CA increased with time of use, while values of AFD, AR showed no variation. The increment of PE with time of use could be explained as a consequence of particle breakdown due to roots, or tiny particle drift from the rhizosphere. Accordingly with the increment of CA, a diminution in one order of magnitude of Kns after 39 months of use was found.