Specific Root Length and Diameter of Hydroponically-grown Tomato Plants under Salinity

Salinity causes great growth and yield reduction on crops in many parts of the world. In order to study the impact of salinity on root systems the aim of this experiment was to investigate how root features of tomato plants cultivated in hydroponics are modified under salt stress conditions. Tomato plants underwent three salinity levels: 2.2, 10 and 15 dS m-1, through NaCl addition, corresponding to 0, 100 and 150 mM NaCl. In hydroponically grown tomato plants it was measured a reduction in total weight and length of the root system as salinity increased and a shallower root system in the more severe treatment. An increase of specific root length was found in the middle section of the root system under high salinity and it corresponded to a significant increase of roots belonging to the lowest diametric class in the more severe salt treatment. It can be considered as an important evidence of an adaptation to salinity in conditions where soil modifications due to salinity do not interfere with direct plant responses.