Introduction
Drip irrigation in processing tomato is a common technique in Portugal due to the Mediterranean climate, with dry and warm summers and high evapotranspiration rates throughout the growing season. These are conditions that make subsurface drip irrigation a suitable alternative to the surface system.With subsurface drip irrigation, evaporation from the topsoil is reduced and water runoff is negligible (Phene, 1991; Phene et al., 1992). In addition, with surface drip irrigation, roots grow preferentially around the emitter area (Oli- veira et al., 1996), which in turn can contribute to improve water availability to the plants when using subsurface drip irrigation. The purpose of the present
study was to compare surface vs subsurface drip irrigation (at two different depths) on the root distribution of two processing tomato cultivars. Knowledge of rooting patterns is essential to irrigation and fertilizer management and consequently to tomato yield and quality. Besides using minirhizotrons for root system analysis, trenches were opened perpendicularly to the plant row to examine the root distribution along the soil profile.