California Agriculture

California processing tomato growers must adapt their irrigation management practices to cope with frequent droughts and increasingly limited groundwater supplies. Processing tomatoes’ water stress tolerance provides a water savings opportunity through deficit irrigation. However, it is important to initiate deficit irrigation at key growth stages to maintain yields. We conducted a deficit irrigation experiment over three years using a randomized block design with four treatments in three commercially operated fields in Fresno County. A tapered deficit treatment was applied, where the amount of water deficit was increased partway through the deficit period to ease the crop into higher water stress while further reducing irrigation. In all three seasons, there were no differences between treatments in yield, with some seasons having an improvement in Brix with the higher deficit treatments. This was achieved with up to a 29% reduction in irrigation compared to the grower’s standard practice. The results of this study suggest that tapered deficit irrigation can be a viable option for optimizing water savings in processing tomato systems.