Effects of irrigation cut-off on processing tomato fruit quality

Water management was monitored in 10 commercial processing tomato fields during the 2001 season to evaluate strategies for improving fruit quality. Fields were selected to represent a range of soil types, irrigation systems (drip, furrow, and sprinkler), and water table depths in Sutter County, CA. Soil textures of fields ranged from clay to sandy clay loam and early season water table depths ranged from 70 cm to > 150 cm below the soil surface. Irrigation trials were conducted to evaluate the effects of early irrigation cut-off on fruit quality at each field site. All trials included a grower (normal cut-off) and an early cut-off treatment. Trials that were located in drip-irrigated fields included deficit (cutback) irrigation treatments. Soil moisture was monitored to a 110-cm depth using a neutron probe at each field site. Fruit yield and quality were evaluated from hand-harvested and machine harvested plots. Early irrigation cut-off was found to increase soluble solids of fruits when treatments were sufficiently severe to reduce soil moisture in the upper 70 cm of the soil profile during fruit ripening. Fruit weight was reduced in the early cut-off treatments at field sites where fruit had increased brix levels. Results were consistent in crops grown under sprinkler, furrow, and drip irrigation and a range of soil textures.