Joint effect of meteorological variables on cowpea stomatal conductance

ABSTRACT

Stomatal conductance (gs) is a physiological variable related to gas exchange (CO₂ and H₂O) between leaf and atmosphere. Therefore, gs is a fundamental process for meteorological research. The aim of this study was to adjust and validate a descriptive model to quantify the effect of the main environmental variables that modulate gs such as air temperature (T), solar irradiance (I_o), vapor pressure deficit in the air (VPD) and soil moisture. The model proposed in this study was calibrated with experimental data carried out in a randomized block design. The potential gs (optimum conditions of soil water) was estimated as a function of the meteorological variables product (T×DPV×I_o ^-1). Following, the potential gs was adjusted to the current condition of soil water, using a water stress factor. The gs values estimated by the model were compared with independent experimental data. Validating tests indicated that the model was satisfactorily sensitive to weather variations and water content available in the soil, due to a low mean absolute error of the estimates (<15%) and a high agreement between the observed and simulated data (d = 0.82).

Keywords:
Vigna unguiculata; crop dynamic model; evapotranspiration