ISHS Acta Horticulturae 664: IV International Symposium on Irrigation of Horticultural Crops
IMPROVING A MODEL FOR PREDICTING PEACH TREE EVAPOTRANSPIRATION |
| Authors: | R. Scott Johnson, J. Ayars, T. Hsiao |
| Keywords: | Water use, lysimeter, irrigation, ET, canopy light interception, Prunus persica |
| Abstract:
A model of young peach tree evapotranspiration (ET) was reported on previously. It was developed using data from the first two years of growth of “Crimson Lady” peaches planted in a large weighing lysimeter. Tree transpiration and soil evaporation were modeled as separate components. The model predicts daily peach tree ET based on reference crop ET (ETo) and several simple measurements from the orchard. Since then, two more years of data have been collected and several improvements to the model have been made. The model can now be used for mature as well as young trees. Tree transpiration was originally modeled as a function of canopy size as measured by light interception at solar noon. A vapor pressure deficit function was added which explains some of the short-term variation observed in the lysimeter trees. Percent canopy light interception of very small trees can be difficult to estimate accurately. Therefore, equations were derived from measurements of tree height and canopy spread, and were verified in the field. To improve the soil evaporation component of the model, an equation was developed to estimate the percent of the irrigation wetted area in full sun over the course of the day for different irrigation systems and planting configurations. The model can now be applied to peach trees of any age and spacing, and a range of irrigation regimes. | |
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