Articles
Use of the VegSyst model to calculate crop N uptake and crop evapotranspiration of autumn- and spring-grown cucumber in Mediterranean greenhouses
Article number
1154_7
Pages
47 – 54
Language
English
Abstract
The VegSyst simulation model has been developed to assist with N and irrigation management of different vegetable crops grown in plastic greenhouses in the Mediterranean Basin.
The model was developed for use in an on-farm decision support system (DSS) to estimate crop N and irrigation requirements.
In the current version, the only inputs are daily data of air temperature inside the greenhouse, outside solar radiation, estimated or measured roof transmissivity, and the dates of the crop.
To date, VegSyst has been calibrated and validated for tomato, sweet pepper and muskmelon.
Given the economic importance of cucumber in south-eastern Spain, this work was conducted to calibrate VegSyst for cucumber crops grown in Mediterranean-type plastic greenhouses.
Two experiments with cucumber were conducted in two different growing seasons, being grown in (a) autumn-winter and (b) spring.
Large differences in solar radiation were observed between the growing periods; values of average daily integral and the accumulated solar radiation, inside the greenhouse, for each growing season were respectively 6.9 MJ m-2 d-1 and 546 MJ m-2 for the autumn-winter period and 10.5 MJ m-2 d-1 and 888 MJ m-2 for the spring period.
The calibration parameters for the autumn-winter crop under lower radiation conditions were not suitable for the spring crop, even though the model is driven by thermal time.
Data from several previous studies of cucumber were used for validation.
The performance of the model to predict accumulated dry matter production (DMP) during the growing period was very good.
The performance of the model to simulate crop evapotranspiration (ETc) was generally acceptable; the errors associated with the estimation of ETc were larger than those with DMP. Simulated values of critical crop N uptake were generally lower than measured crop N uptake, confirming that these crops were not N-limited.
Data used for validation were obtained at different sites, in different types of greenhouse, and with different varieties and planting densities from the calibration crops, demonstrating the robustness of the VegSyst model for cucumber.
The model was developed for use in an on-farm decision support system (DSS) to estimate crop N and irrigation requirements.
In the current version, the only inputs are daily data of air temperature inside the greenhouse, outside solar radiation, estimated or measured roof transmissivity, and the dates of the crop.
To date, VegSyst has been calibrated and validated for tomato, sweet pepper and muskmelon.
Given the economic importance of cucumber in south-eastern Spain, this work was conducted to calibrate VegSyst for cucumber crops grown in Mediterranean-type plastic greenhouses.
Two experiments with cucumber were conducted in two different growing seasons, being grown in (a) autumn-winter and (b) spring.
Large differences in solar radiation were observed between the growing periods; values of average daily integral and the accumulated solar radiation, inside the greenhouse, for each growing season were respectively 6.9 MJ m-2 d-1 and 546 MJ m-2 for the autumn-winter period and 10.5 MJ m-2 d-1 and 888 MJ m-2 for the spring period.
The calibration parameters for the autumn-winter crop under lower radiation conditions were not suitable for the spring crop, even though the model is driven by thermal time.
Data from several previous studies of cucumber were used for validation.
The performance of the model to predict accumulated dry matter production (DMP) during the growing period was very good.
The performance of the model to simulate crop evapotranspiration (ETc) was generally acceptable; the errors associated with the estimation of ETc were larger than those with DMP. Simulated values of critical crop N uptake were generally lower than measured crop N uptake, confirming that these crops were not N-limited.
Data used for validation were obtained at different sites, in different types of greenhouse, and with different varieties and planting densities from the calibration crops, demonstrating the robustness of the VegSyst model for cucumber.
Authors
M. Gallardo, C. Gimenez, M.D. Fernández, F.M. Padilla, R.B. Thompson
Keywords
nitrogen management, Cucumis sativus, decision support system, vegetable
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