yaser hossini; Javad Ramezani Moghaddam; Mohammad Reza Nikpour; Attieh Abdoli
Abstract
Various mathematical models are available for predicting the response of plants to combined water and salinity stress and their share in water uptake. The reduction functions are classified as additive, multiplicative, and conceptual models. In this study, 6 macroscopic reduction functions, namely, Van ...
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Various mathematical models are available for predicting the response of plants to combined water and salinity stress and their share in water uptake. The reduction functions are classified as additive, multiplicative, and conceptual models. In this study, 6 macroscopic reduction functions, namely, Van Genuchten (additive and multiplicative), Dirksen et al., Van Dam et al, Homaee and Skaggs were evaluated in a greenhouse experiment on cherry tomato, var. cherry tomato cluster. This experiment was performed based on a completely randomized design with 3 replicates and 2 levels of salinity (4 and 7 dSm-1). Water stress levels were imposed as matric potential decline during the study at 3 levels of available water depletion (40%, 50%, and 65%). The result of the study indicated that the crop response to water stress and salinity stress was incremental at 4 and 7 dSm-1 salinity levels. Among the multiplicative models, reduction functions of Dirksen model had better fit than others at 4 dSm-1 salinity level (RMSE=0.15 and ME=0.14).However, at 7 dSm-1, Van Dam (RMSE=0.017, ME=0.09) and Skaggs (RMSE=0.018, ME=0.14) had better fit to the measured data.
y h; h b; b kh
Abstract
Various mathematical models are available for estimating the response of plants to combined drought and salinity stress and the share of each component in water uptake. The reduction functions are classified as additive, multiplicative, and conceptual models. In this study, 5 different macroscopic reduction ...
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Various mathematical models are available for estimating the response of plants to combined drought and salinity stress and the share of each component in water uptake. The reduction functions are classified as additive, multiplicative, and conceptual models. In this study, 5 different macroscopic reduction functions, namely, Van Genuchten (additive and multiplicative), Dirksen et al., Van Dam et al, and Homaee, were evaluated in greenhouse conditions using pepper data. This experiment was performed based on a completely randomized design with 3 replicates and 3 levels of salinity (2.5, 4.5, and 6.5 dS/m). Drought levels were carried out as matric potential during the experiment at 3 levels (50%, 60%, and 70% of field capacity). The results of this study indicated that the crop response to drought and salinity stress was additive at low salinity level (2.5 dS/m) and multiplicative at 4.5 and 6.5 dS/m salinity levels. Also, reduction function of Van Genuchten (average RMSE=3%, ME=0.15) had the best fit at low salinity level (2.5 dS/m). Among the multiplicative models, reduction functions of Dirksen model at 4.5 dS/m with average RMSE=5% and ME=0.09 was in better fit to the measured data than the other functions.Homaee (average RMSE=9%, ME=0.12) and Vandam models (average RMSE=9%, ME=0.11) at higher salinity level (6.5 ds/m) were in better fit to the measured data than the other functions.