Proteção de gotejadores a obstrução por intrusão radicular em irrigação subsuperficial de figueiras

Abstract

An experiment of surface and subsurface drip irrigation in figs was held in Santa Maria, Rio Grande do Sul state, with aim of evaluate the disposables materials efficiency for protecting water emitters in subsuperface irrigation against root intrusion. The experiment was conducted in a randomized block design with four replications. The treatments were five irrigation options: A - no irrigation, B - drip tape; C - surface drip, D - subsurface drip-protected with rice husk, and E - subsurface drip-protected with polyethylene terephthalate (PET) bottles. In subsurface irrigation the effect of the emitter protections was analyzed on root intrusion and response variables of fig trees (fruits diameter and number per plant, plant production and productivity, and final dry mass of roots). For the process of root intrusion in buried emitters, an index of root intrusion (IRI) was created and after an index of root intrusion (IIR) subsurface was determined. The final dry mass of roots was determined in all treatments. It was found that the PET bottle protect the emitters in subsurface irrigation against obstruction by root intrusion. The use of rice husk is an inadequate technique for protecting emitters in subsurface irrigation, because it provides favorable conditions for root intrusion, which significantly to reduce flow of the emitters. The root intrusion due to the use of rice hull around the emitters in subsurface irrigation can negatively affect the fig tree response variables, which, in periods of insufficient rainfall, does not allow greater productivity than that obtained without irrigation. The lack of supplementary irrigation, when dry periods occur during the harvest period, reduces the fruits diameter, average weight, and the number of fruits per plant. The root dry mass per plant is not significantly influenced by any form of irrigation, that is, the values found were similar to values found in non-irrigated soil at any level from surface to the 40 cm soil depth.