Use of germination and early radicle growth parameters for assessing oxidative stress tolerance in zucchini squash

Plants are constantly exposed to unfavorable environmental conditions. Most of abiotic stresses can induce the production of reactive oxygen species (ROS) causing oxidative damage and generating various negative effects on growth and development of crops. Here we present the optimization of a fast phenotyping method for assessing the oxidative-stress tolerance of different cultivars of zucchini during seed germination and early root growth. Seeds of each cultivar were soaked in 1% H2O2 and 0.05 mM of Aminotriazole (a catalase inhibitor) for 12 h at 25 degrees C and subsequently germinated and grown vertically in darkness at 24 degrees C and 80% RH for 48 h between two glass plates (12x20 cm) arranged on foam rubber and filter paper. Water soaked seeds of the same cultivar were used as control. Germination and radicle growth were assessed every 2 h using digital image processing for evaluate the tolerance of genotypes to oxidative stress. The cultivars were clustered on the base of their differential response to the treatment in both germination and root growth. Results demonstrated the existence of genetic variability for oxidative stress tolerance among zucchini squash genotypes. This fast method could be used as a high throughput phenotyping screening to select tolerance to nutritional and environmental stresses in zucchini breeding programs.