The distribution of tomato rooting system and horizontal variability of matric potential (psim) and electrical conductivity of the solution were evaluated on green coconut fiber, carbonized rice husk, carbonized coarse sawdust and commercial substrates packed in plastic bags. Each plant was irrigated by a single dripper, set up 7 cm apart. Higher root concentrations and lower psim, under temporary water deficit conditions, occurred close to the plant for coconut fibers and rice husk, and close to the dripper for coarse sawdust and commercial substrates. The lower root concentration between a dripper and the following plant, irrigated by another emitter, occurred probably due to the high electrical conductivity of the nutrient solution in that zone (up to 8.3 dS m-1). Correlations between root concentration versus Ym and root concentration versus electrical conductivity were significant for all substrates. Evaluation of psim variability on substrates for plants exposed to water deficit allowed a qualitative estimation of the root system distribution of tomato crop, easier than the direct method. For irrigation scheduling purpose, moisture sensors should be placed between the plant and its respective dripper.
Lycopersicon esculentum; electrical conductivity; matric potential; osmotic potential; tensiometer
