Articles
USE OF FOLIAR FERTILIZATION TO OFFSET EFFECTS ON NAVEL ORANGE YIELD DUE TO REDUCED WATER AND FERTILIZER APPLIED BY PARTIAL ROOT ZONE DRYING VERSUS CONVENTIONAL IRRIGATION
Article number
984_27
Pages
237 – 245
Language
English
Abstract
With increasing costs, reduced availability of quality irrigation water and the possibility that California growers might have to produce citrus with 30% less water, our research goal was to meet the challenge of California’s water shortage crisis by demonstrating that yield of commercially valuable large navel orange fruit can be sustained despite irrigating citrus trees with 25% or 50% less water.
The efficacy of using partial root zone drying (PRD) to reduce the amount of water and irrigation-applied fertilizer used to produce navel oranges, combined with foliar fertilization to sustain the yield of commercially valuable large-size fruit and, thus, increase grower net income was tested.
Specific objectives were: (1) to reduce annual water use in a commercial navel orange orchard by alternately wetting and drying the root zone on two sides of the tree (PRD) at irrigation rates 25% and 50% less than the well-watered control under conventional irrigation (CI); (2) to compare PRD treatments with CI at 25% and 50% less water (CI-RR) than the well-watered control; (3) to determine the effect of supplementing PRD and CI-RR treatments with foliar fertilization (especially N and K to ensure adequate nutrition to sustain yields of large-size fruit) on yield, fruit size and quality compared to well-watered control trees receiving irrigation-applied fertilizer; and (4) to provide a cost:benefit analysis.
Even modest reductions of only 20% in the amount of irrigation water applied during the critical period of exponential fruit growth reduced the yield of commercially valuable fruit (packing carton sizes 88, 72, and 56) and grower income.
Neither foliar-applied fertilizers, nor irrigation-applied cytokinin (6-benzyladenine) mitigated the effects of reduced irriga¬tion rates on yield or fruit size.
Savings in annual water use at reduced irrigation rates did not offset the revenue losses resulting from lower yields and smaller fruit size caused by reduced irrigation rates.
The efficacy of using partial root zone drying (PRD) to reduce the amount of water and irrigation-applied fertilizer used to produce navel oranges, combined with foliar fertilization to sustain the yield of commercially valuable large-size fruit and, thus, increase grower net income was tested.
Specific objectives were: (1) to reduce annual water use in a commercial navel orange orchard by alternately wetting and drying the root zone on two sides of the tree (PRD) at irrigation rates 25% and 50% less than the well-watered control under conventional irrigation (CI); (2) to compare PRD treatments with CI at 25% and 50% less water (CI-RR) than the well-watered control; (3) to determine the effect of supplementing PRD and CI-RR treatments with foliar fertilization (especially N and K to ensure adequate nutrition to sustain yields of large-size fruit) on yield, fruit size and quality compared to well-watered control trees receiving irrigation-applied fertilizer; and (4) to provide a cost:benefit analysis.
Even modest reductions of only 20% in the amount of irrigation water applied during the critical period of exponential fruit growth reduced the yield of commercially valuable fruit (packing carton sizes 88, 72, and 56) and grower income.
Neither foliar-applied fertilizers, nor irrigation-applied cytokinin (6-benzyladenine) mitigated the effects of reduced irriga¬tion rates on yield or fruit size.
Savings in annual water use at reduced irrigation rates did not offset the revenue losses resulting from lower yields and smaller fruit size caused by reduced irrigation rates.
Authors
B.A. Faber, C.J. Lovatt
Keywords
fruit size, fruit quality, tree nutrient status, cost:benefit analysis
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