ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
EVALUATION OF A MODEL BASED ON REFERENCE CROP EVAPOTRANSPIRATION (ETO) FOR PRECISION IRRIGATION USING OVERHEAD SPRINKLERS DURING NURSERY PRODUCTION OF LIGUSTRUM JAPONICA |
| Authors: | R.C. Beeson, Jr., J. Brooks |
| Keywords: | nursery production, woody ornamentals, irrigation control, modeling |
| Abstract:
A model for automated precision irrigation of Ligustrum japonica developed from lysimeter data collected in 2001-2002 was used to produce market size plants in 11.4 L black polyethylene containers. The model calculated daily irrigation rates based on the previous day ETo and a water needs index (WNI – a crop coefficient-like value derived from percent canopy closure). Percent canopy closure was calculated by squaring average canopy width and dividing by allocated plant area then multiplying by 100. Average canopy width was determined manually and input every 3 weeks during production. Plant allocated area was increased once. ETo was calculated using instrumentation of a standard weather station connected to the irrigation controlling data logger. Plant growth and irrigation applications were compared to those of plants whose irrigation frequency and volume were adjusted manually to approximate 1800 mm of overhead irrigation annually. Each irrigation regime was replicated 4 times. ETo controlled irrigation produced the same marketable size plants as the manual regime, but 3 weeks faster, with 400 mm less irrigation. The model functioned well without modification during the winter quiescent period and sequential spring growth flush. | |
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