Basil root water uptake derived models under combined water and nitrogen deficit conditions

Abstract

AbstractThe objective of this research was to introduce and evaluate derived models under simultaneous water and nitrogen deficit stress conditions and consequently calibrating their parameters for basil. Therefore to do so, in order to introduce and evaluate derived models under simultaneous water and nitrogen deficit stress conditions, derived models from the composition of Mitscherlich–Baule (MB) for nutrient stress conditions and the models of Feddes (F), van Genuchten (VG), recommended exponential (EXP) and Homaee (H) for water stress conditions and also the composition model of Liebig–Sprengel (LS) for nutrients and the model of Feddes (F) for water stress conditions were presented and evaluated. This experiment was conducted with four irrigation water quantity levels of 120, 100, 80 and 60% of crop water requirement and four nitrogen fertilizer levels of 100, 75, 50 and 0% of fertilizer requirement based on a soil fertility test with three replicates. The results indicated that of the evaluated models, based on calculated statistical indices, the derived models of MB‐EXP, MB‐F, MB‐VG and MB‐H (mentioned above) had the best fitting on the measured data, respectively, compared to actual data. The results of calculated statistics to compared models based on the different nitrogen and water irrigation levels indicated that MB‐EXP and MB‐F using nRMSE statistics were 2.78 and 3.64, and EF statistics of both was 0.99% and they showed the highest accuracy in estimating basil yield. Copyright © 2017 John Wiley & Sons, Ltd.