Modelling oil seed camelina response to water stress

Water stress is one of the dominant stresses limiting crop growth and yield, particularly in arid and semi-arid regions. The best strategy to deal with water stress is choosing a water-tolerant plant based on reliable screening methods such as polyethylene glycol (PEG). To evaluate different predictive models and quantitatively investigate camelina response to drought stress during the germination stage, an experiment was conducted in a completely randomized design with three replications. Water stress treatments included six matric potentials of PEG6000: 0 (control, without stress), 3000, 6000, 9000, 12000, 15000, 18000 cm. Germination indicators were calculated using the SeedCalc package in R software and MATLAB was used for programming and models fitting. Water stress models including Feddes et al. (F), van Genuchten (VG), Dirksen and Augustijn (DA) and Homaee (H) were assessed and compared afterwards. Data analysis was performed using SAS software (V. 9.4). The threshold values under germination rate (GSI), mean seedling length (M-SL), mean root-to-stem ratio (Razao) and seed vigor (SV-S)) were then obtained for the control, 6000, 3000 and 3000 cm, respectively. According to these four germination indices, the camelina is very tolerant to water stress. In all four indicators of GSI, M-SL, SV-S and Razao, the H model presented the best performance. The highest values of GSI, Razao, M-SL, stem and root length were obtained at matric potentials of control, 3000, 6000, 3000 and 6000 cm, respectively, indicating the suitability of camelina cultivation in areas under water shortage.