Morphological and physiological responses of two tomato genotypes (Solanum lycopersicum L.) under flooding

VIDOZ, M.L.; MIGNOLLI, F.; AISPURU, H.T.; MROGINSKI, L.A.

Mar del Plata

Congreso; XXIX Reunión Argentina de Fisiología Vegetal; 2012

Flooding is one of the most frequent and extensive abiotic stresses. It negatively influences terrestrial plant growth and productivity, affects the composition of plant populations and may lead to plant death. Roots are the first organs tobe affected by soil waterlogging, which often results in death of the root system. Species that are able to generate adventitious rootshave a better chance to survive or recover from the flooding stress. In addition, plants often respond by increasing stem and root aeration to facilitate oxygen arrival to submerged tissues. The aim of this study was to evaluate the response of two tomato genotypes to flooding stress. Tomato plants cv Ailsa Craig (AC) and aerial roots-1 (aer-1) were used for all experiments. Aer-1 mutant is characterized by the abundant production of adventitious root primordia along the stem. Three-, 4-, 5- and 6-week old plants were submerged 2 cm above ground level during 7 days. Plants used as controls were kept at field capacity. After a week, the number and length of adventitious roots, and stem diameter were quantified. Four-week old plants were used to determine the root/shoot ratio after a week of treatment. The number of adventitious roots in flooded plants increases in both genotypes with the age of the plant. Root length decreases in AC in 6-week old plants, but slightly increases in aer-1. Diameter of submerged stems significantly increased in flooded plants of both genotypes, but hypertrophy in AC stems was higher than in aer-1. In fact, porosity significantly increased in AC but not in mutant plants, which could be related to the formation of aerenchyma. Interestingly, both genotypes presented epinasty in second and third leaves after a week of treatment. Root to shoot ratio decreased in both genotypes after a week of treatment, probably due to the death of the original root system. Further studies are being conducted in order to assess if aer-1 mutant is more tolerant to flooding conditions.