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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 3/22/2011 Publication Date: 5/23/2011 Citation: Wang, D. 2011. Deficit irrigation of peach trees to reduce water consumption. pp. 497-505. In: C.A. Brebbia and V. Popov (eds.) Water Resources Management VI, WIT Press, Southampton, UK. Interpretive Summary: Fresh water is becoming less available to agriculture with increasing demands from urban, industrial, and environmental or recreational needs. Deficit irrigation has been studied as a means of reducing total crop water consumption for fruit trees because fruit yield and quality at harvest may not be sensitive to water stress at some developmental stages such as during non-fruit bearing postharvest season. The objective of this study was to evaluate effect of deficit irrigation on yield and quality of early-ripening peaches. Results indicated that with approximately 30-40% of the full seasonal water use, deficit irrigation with furrows produced peach yield similar to full irrigation. With subsurface drip irrigation, deficit water application at 25-30% of the full rate reduced the yield in the first year but not the second year. Smaller fruit sizes were found under the severe deficit treatment in the subsurface drip irrigation method. Crop water stress index was estimated and consistently higher values were found in the deficit irrigation than in the full irrigation control treatments. The study showed that deficit irrigation is a potential management technique for reducing crop water use at non critical stages of growth. The questions remain in the determination of optimum amount of deficit without causing yield losses or losses in product quality, such as fruit size. Technical Abstract: Lack of water is a major limiting factor for production tree fruits such as peaches in the San Joaquin Valley of California and many other arid- or semi-arid regions in the world. Deficit irrigation can be used in some cropping systems as a water resource management strategy to reduce non-productive water consumption. A difficulty in using deficit irrigation is the lack of techniques for quickly and accurately measuring plant water status so as not to cause irreversible damage on the plants, especially in perennial species such as vine and tree crops. Field measurements and analyses were carried out in a multi-year experiment to evaluate deficit irrigation strategies for managing postharvest reduced water application of peach trees. Micrometeorological variables were collected near the center of the orchard for energy balance computations and infrared temperature sensors were installed in different field areas which received full or deficit irrigation treatments. Results indicated that with approximately 30-40% of the full seasonal water use, deficit irrigation with furrows produced peach yield similar to full irrigation. With subsurface drip irrigation, deficit water application at 25-30% of the full rate reduced the yield in the first year but not the second year. Smaller fruit sizes were found under the severe deficit treatment in the subsurface drip irrigation method. Measured midday canopy to air temperature differences in the water-stressed postharvest deficit irrigation treatments were consistently higher than that in the full irrigation control treatments. Crop water stress index was estimated and consistently higher values were found in the deficit irrigation than in the full irrigation control treatments. The study clearly showed that with carefully measured water stress levels, deficit irrigation is a potential management strategy for reducing water consumption in growing peaches. |
