Water management strategies for improving fruit quality of drip-irrigated processing tomatoes

Water management during fruit sizing and ripening can affect quality and yield of drip-irrigated processing tomatoes. Growers managing subsurface drip systems often delay termination (cut-off) of irrigation later in the season than they would normally do with furrow and sprinkler irrigation. Although cutting off irrigation late can improve yields, it can also lower the soluble solids content of fruit. We conducted replicated trials to compare late-season water management strategies for optimizing fruit yield and quality in drip-irrigated processing tomatoes during the 1998 and 1999 seasons. All plots were irrigated at 100% of crop evapotranspiration (ETc) demand until treatments were imposed. Treatments included cut-off of irrigation 0, 1, 2, and 3 weeks earlier than conventional cut-off dates (2 or 3 weeks before harvest), or deficit (cutback) irrigations of 70% and 85% of ETc demand during the 3-week period before the conventional date of irrigation cut-off. Results of the 1998 and 1999 trials demonstrated that irrigation treatments significantly affected fruit yield and quality. However, cutback and cut-off strategies equally influenced fruit yield and quality when similar amounts of water were applied. The most important factor affecting fruit quality and yield was the amount of water applied during fruit ripening. Reducing water applications to amounts ranging from 70% to 85% of ETc during the period between 7% and 66% red fruit, either by cutting-off or by cutting back on water, appeared to be the best management strategy to optimize fruit yield and quality.