ISHS Acta Horticulturae 664: IV International Symposium on Irrigation of Horticultural Crops
LATE-SEASON WATER MANAGEMENT EFFECTS ON QUALITY AND YIELD OF PROCESSING TOMATOES |
| Authors: | M.D. Cahn, E.V. Herrero, B.R. Hanson, T.K. Hartz, E.M. Miyao |
| Keywords: | Lycopersicon esculentum, fruit brix, soluble solids, soil moisture tension, soil texture, water table. |
| Abstract:
Growers trying to raise fruit quality often stress processing tomatoes (Lycopersicon esculentum) during ripening by cutting back irrigation. Because the amount that growers need to cut-back on irrigation to optimize fruit quality and yield may be site-specific it is difficult to make recommendations on late-season irrigation management. We conducted replicated irrigation trials in 16 commercial processing tomato fields to evaluate strategies for improving fruit quality under various types of soil conditions during the 2001 and 2002 seasons. Fields were selected to represent a range of soil types, irrigation systems (drip, furrow, and sprinkler), and water table depths in the Sacramento Valley of California. Soil textures of fields ranged from clay to silty-clay loam and water table depths ranged from 60 cm to greater than 150 cm below the soil surface. All trials included a conventional (3 to 5 weeks before harvest) and an early cut-off treatment (1 to 2 weeks before conventional treatment). Soil moisture was monitored in each plot to a 110-cm depth using a neutron probe. Fruit yield and quality were evaluated from hand-harvested and machine harvested plots. Trial results showed that early cut-off or irrigation significantly increased brix levels, improved fruit color, and decreased fruit size. Irrigation cut-off also decreased yields by an average of 3.1 Mg/ha per increase of 0.1 °Brix. Brix-yields were not significantly different between irrigation treatments. Fruit quality and yields also varied significantly among trial sites. The highest brix-yields were measured on clay-loam soils without the presence of a shallow water table and the lowest brix-yields were measured on clay soils with a shallow water table persisting throughout the season. Sites with Fusarium Wilt had reduced fruit yields and high brix levels. Differences in brix levels between irrigation treatments and among sites were correlated to soil moisture tension in the 15-75 cm soil layer during the period from fruit ripening to harvest. | |
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