Nitrogen supply effect on lettuce response to Botrytis cinerea and Sclerotinia minor

Background information: Cultural practices play an important role on the development of pathogens (Datnoff, et al. 2007). In this context, several authors have been interested in studying the effects of mineral nutrition on the resistance of vegetables and fruits to fungi during storage, especially nitrogen. The purpose of the study: In this work we tested the effects of three contrasted regimes of nitrogen supply, with nitrate concentrations in the nutrient solutions of 2 mM (low), 10 mM (normal) and 20 mM (high) on the susceptibility of Lactuca sativa L towards Botrytis cinerea (BC87) and Sclerotinia minor (SM) during storage. Once harvested, the outerleaves of the plants derived from the three nitrogen regimes were inoculated with either Botrytis cinerea (BC87) or Sclerotinia minor (SM). Data showed that the resistance to this two pathogens increase when plants were developed under low nitrogen concentration. This resistance observed is correlated with low values in oxidative stress indicators (MDA and H2O2) and high values in total phenols.