Validation of coupled brown planthopper-infocrop rice simulation model and yield loss under elevated CO2

Abstract

Coupled brown planthopper (BPH)-ICAR-InfoCrop rice simulation model was validated with BPH population and crop yield under elevated CO2 vis-a-vis ambient CO2 experiments during 2013 and 2014. Under ambient CO2, simulated BPH number varied from 13 to 118/hill compared to observed population of 11 to 92/hill; while in simulated varied from 19 to 177/hill in comparison to the observed 16 to 168/hill under elevated CO2 during 2013. Likewise, during 2014 simulated BPH population ranged from 9 to 68/hill compared to observed population of 10 to 65/hill under ambient CO2, whereas simulated one was found to be between 15 to 88 compared to 9 to 80/hill observed under elevated CO2. Simulated and observed BPH number were thus found to be proximal under elevated CO2 (R² = 0.96; p<0.0001) and ambient CO2 (R² = 0.89; p<0.0001) during the first year as well as during second year under elevated CO2 (R² = 0.93; p<0.0001) and ambient CO2 (R² = 0.85; p<0.0001), reflecting appropriate validation of the BPH population dynamics model. Simulated yield loss during 2013 was 19.6% compared to observed yield loss of 23.1% under ambient CO2, with corresponding losses of 34.5 and 38.5% under elevated CO2. In 2014, simulated yield loss was 11.7% in contrast to 14.4% observed under ambient CO2, whereas simulated and observed yield loss was 25.2 and 29.91%, respectively under elevated CO2. The modelling approach presented herein provides an outline for future risk of rice yield loss due to BPH in India under climate change scenarios.