Modeling the effect of salinity application time of root zone on yield of canola (Brassica napus L.)

Canola response to root media salinity highly depends on its phenological stage. In most investigations, this fact is neglected. Therefore in most studies a single threshold value for each plant is introduced. The objective of this study was to investigate the quantitative response of canola to salinity. The study was done in two different experiments. In the first experiment, canola was exposed to salinity from the first growth stage. In second experiment, plants were irrigated with saline water only at final growth stage. Both experiments were conducted on a natural saline loamy sand soil, using salinity treatments including a non-saline water (tap water) and eight saline waters of levels (3, 5, 7, 11, 13, 15 and 17 dS.m-1). The Maas and Hoffman, van Genuchten and Hoffman, Dirksen et al., and Homaei et al., models were used to predict relative yield as a function of soil salinity. The obtained results based on the calculated maximum error (ME), root mean square error (RMSE), coefficient of determination (CD), modeling efficiency (EF) and coefficient of residual mass (CRM) statistics indicated the Homaee et al., model provides better prediction for both experiments.