Water uptake and proline index as indicators of predisposition in tomato plants to Phytophthora nicotianae infection as influenced by abiotic stresses

To identify quantitative indicators of predisposition and stress development in tomato (Lycopersicon esculentum Mill. cv. Counter) plants infected by Phytophthora nicotianae Breda de Haan, we examined plants grown under stress-inducing nutrient conditions exposed to different levels of radiation and infection. The plant's response was investigated by analysing plant growth, proline content and disease development. From all plant growth parameters investigated, only leaf surface area and total fresh mass showed a response to radiation and infection, and both indicators were strongly correlated. However, because of the destructive character of these indicators, non- or minimal destructive indicators were sought. To this end, here we report that water uptake per plant (WP) and water uptake per plant and day (WPD) and proline content of leaves represent useful tools to assess plant health status during growth.