Adapting the cropgro model to simulate growth and yield of spring saffl ower in semiarid conditions

The importance of saffl ower (Carthamus tinctorius L.) is increasing as a low input, stress-tolerant oilseed crop around the world. Adapting a crop growth model for saffl ower will help to assess the feasibility of this crop under diverse environmental conditions with relatively limited fi eld experimentation. Th e objective of the project was to adapt the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM-CROPGRO) to simulate growth and seed yield of spring saffl ower. Th e CROPGRO template approach was used, and parameters in species and cultivar fi les were developed based on saffl ower literature and calibration to fi eld data. Th e entered base temperatures for photosynthetic, vegetative, and reproductive processes of saffl ower ranged from 0 to 5°C while corresponding optimum temperatures varied from 19 to 40°C. Simulated results were compared with observed data collected from fi eld experiments conducted at Clovis, NM, during 2013 and 2014. Th e model predicted the crop life cycle (anthesis and harvest maturity date) with relative root mean square error (RRMSE) of 0.07. Average plant biomass, head mass, head number and seed number were satisfactorily simulated when compared to observed values. Seed yield, averaged over irrigation treatments and years, was predicted as 1963 kg ha–1 compared to measured value of 1902 kg ha–1 with RRMSE of 0.12. Reasonable prediction of phenology, growth, and yield by the model adapted for saffl ower suggested that the CROPGRO-saffl ower model is promising to simulate saffl ower production in semiarid climates. However, further testing of the CROPGROsaffl ower model under different environments is needed.