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Estimating cucumber crop coefficients under different greenhouse microclimatic conditions
Georgios Nikolaou1, Damianos Neocleous2, Evangelini Kitta3
1Department of Agriculture Crop Production and Rural Environment, School of Agricultural Sciences, University of Thessaly, Fytokou Str., 38446, Volos, Greece. gnicolaounic@gmail.com.
International Journal of Biometeorology
|September 21, 2023
Summary
Cucumber crop coefficients (Kc) vary with greenhouse microclimate, impacting transpiration estimation. Direct measurements and FAO 56 methods revealed Kc values from 0.45 to 0.94, suggesting Kc should not be constant.
Area of Science:
- Agricultural Science
- Horticultural Science
- Environmental Science
Background:
- Accurate crop evapotranspiration (ETc) estimation is crucial for efficient irrigation management in controlled environments.
- Greenhouse microclimatic variations significantly influence plant physiological processes and water use.
- The Priestley-Taylor model is widely used for reference evapotranspiration (ETo) but requires accurate parameterization for specific crops and conditions.
Purpose of the Study:
- To determine cucumber crop coefficients (Kc) under varying greenhouse microclimatic conditions.
- To parameterize the Priestley-Taylor reference evapotranspiration model for greenhouse cucumbers.
- To evaluate the relationship between crop coefficients and leaf area index (LAI) for improved ETc modeling.
Main Methods:
- Direct measurement of crop evapotranspiration using lysimeters.
- Computation of crop coefficients (Kc) following the FAO 56 two-step method.
- Analysis of microclimatic data from cooled and uncooled greenhouse compartments.
Main Results:
- Reference evapotranspiration (ETo) differed by up to 12% between cooled and uncooled greenhouse compartments.
- Cucumber crop coefficients (Kc) ranged from 0.45 to 0.94 across different growth stages and microclimates.
- A strong correlation was found between Kc and leaf area index (LAI), yielding the equation Kc = 0.447 × LAI.
Conclusions:
- Greenhouse microclimate significantly affects cucumber crop coefficients, necessitating dynamic Kc values.
- Constant Kc values are not recommended for transpiration estimation due to hourly microclimatic variations.
- Leaf area index provides a reliable and simple predictor for estimating cucumber crop coefficients and evapotranspiration.
