Water management strategies to enhance fruit solids and yield of drip irrigated processing tomato

Processing tomato (Lycopersicon esculentum Mill.) cv. H9553 was used to investigate the effects of water management strategies on fruit yield, quality and solids production in southwestern Ontario over a 3-yr period (2003-2005). Treatments included four levels of drip irrigation (1.2, 1.0, 0.8 and 0.5 of potential crop evapotranspiration, ETc) during the growing season, three preharvest water cutoff times (4, 3 and 2 wk preharvest) and an unirrigated treatment. Irrigation generally increased total and marketable fruit yield, increased the average fruit weight and reduced green fruit yield and blossom-end rot when compared with the unirrigated treatment. Percent fruit solids were reduced, but total solid yields (t ha(-1)) were increased by irrigation. In a dry year (2005), fruit and total solid yields increased with irrigation water level but were not affected by the preharvest water cutoff time. In wetter years, the irrigation regime that applied the least water (0.5 ETc) reduced the amount of water applied to the crop while maintaining high yields and fruit quality. Fruit maturity, colour, firmness and the amount of culled fruit were not influenced by either the irrigation water level or the preharvest water cutoff time. The irrigation regime that applied the least water when used in combination with an early preharvest water cutoff appeared to counteract the reduction in percent fruit solids associated with irrigation. Some reduction in yield may occur with this irrigation regime and rainfall may interfere with implementation of this strategy.