Efeito da irrigação na distribuição espacial de nematoides em áreas cultivadas com cana-de-açúcar

Abstract

Sugarcane is one of the most expressive crops in Northeast of Brazil, and the crop with the largest irrigated area, emphasizing the drip irrigation for a more efficient use of water. Among factors decreasing the crop productivity highlight the plant-parasitic nematodes, which move through the water film in the soil. However, field studies on nematodes moving in the soil are scarce. The objective of this work was to evaluate the effect of drip irrigation on nematode’s spatial distribution in area cultivated with sugarcane in coastal board. The study covered three intervals of time: one month before, three and six months after subsurface drip irrigation. Soil samples were collected a 0.20 m equidistant points in surface, forming a regular horizontal net, and at 0.20, 0.40, and 0.60 m deep. The soil physical characterization was performed through textural analysis, particle density, soil density, hydraulic conductivity and water retention curve in the soil; and nematodes were identified and classified within trophic groups. Data were submitted to univariate and multivariate analysis with repeated measures, and contour maps were produced. Nematodes (plant-parasitic or not) were more abundant at 0.20 m deep, but higher soil population was associated with higher soil macro and total porosity. The population of plant-parasitic nematodes, mainly Meloidogyne and Pratylenchus, increased three months after starting irrigation and aggregated in out edge of the wet bulb presenting difficult in moving opposite to 1,0 L-1 water flow. Inversely, Helicotylenchus and Criconemella kept inside wet bulb with lower difficult to move contrary to flow. Free living nematodes distributed smoothly in time, showing to be less affected by irrigation and precipitation.