Tomato yield-evapotranspiration relationships, seasonal canopy temperature and stomatal conductance as affected by irrigation

Abstract

The effects of irrigation on evapotranspiration (ET), yield, crop canopy temperature and stomatal conductance of tomatoes (Lycopersicon esculentum Mill.) were investigated in Fox sandy loam in the sub-humid region of southwestern Ontario between 1979 and 1982. Optimum yields were obtained with 300–400 mm of total applied water (rainfall plus irrigation). There appeared to be a distinct threshold seasonal ET value of 88 mm, below which yield was negligible and above which yield rose linearly with the seasonal ET rate. The values of crop canopy temperature and leaf stomatal conductance were not significantly different among different levels of irrigation. Leaf stomatal conductance was significantly lower for non-irrigated tomatoes in a dry year indicating that they were subjected to the greater degree of water stress. Key words: Lycopersicon esculentum, irrigation, water stress