Evaluation of WARM for different establishment techniques in Jiangsu (China).

WARM is a model for rice simulation accounting for key biotic and a-biotic factors affecting quantitativeand qualitative (e.g., amylose content, chalkiness) aspects of production. Although the model is used indifferent international contexts for yield forecasts (e.g., the EC monitoring and forecasting system) andclimate change studies, it was never explicitly evaluated for transplanting, the most widespread riceestablishment method especially in tropical and sub-tropical Asia. In this study, WARM was tested forits ability to reproduce nursery growth and transplanting shock, using data on direct sown and trans-planted (both manual and mechanical) rice collected in 24 dedicated field experiments performed at eightsites in Jiangsu in 2011, 2012 and 2013. The agreement between measured and simulated abovegroundbiomass data was satisfactory for both direct sowing and transplanting: average R2of the linear regres-sion between observed and simulated values was 0.97 for mechanical transplanting and direct sowing,and 0.99 for manual transplanting. RRMSE values ranged from 5.26% to 30.89%, with Nash and Sutcliffe modelling efficiency always higher than 0.78; no notable differences in the performance achieved for cal-ibration and validation datasets were observed. The new transplanting algorithm – derived by extendingthe Oryza2000 one – allowed WARM to reproduce rice growth and development for direct sown andtransplanted datasets (i) with comparable accuracy and (ii) using the same values for the parametersdescribing morphological and physiological plant traits. This demonstrates the reliability of the proposedtransplanting simulation approach and the suitability of the WARM model for simulating rice biomassproduction even for production contexts where rice is mainly transplanted.