RIDEV V2 predicts flowering and crop maturity time for transplanted or direct seeded, non-water limited rice crops on the basis of thermal time and day length. It also predicts the fraction of sterile spikelets on the basis of chilling (microspore stage) and heat stress (flowering stage), but does not simulate biomass or grain yield. It requires daily minimum and maximum air temperatures, sowing date and latitude as inputs. In addition, a full set of standard weather station variables is required for the case of flooded rice and its associated micro-climate, for which floodwater, panicle temperature and the time of day of anthesis (TOA) are simulated. Genotypic parameters are used to simulate genotype effects.

RIDEV V2 can be used as a predictive tool for agronomic applications (e.g., decision support to minimize climatic risks by choice of genotype and sowing date) or as a phenotyping tool for genetic analyses. In the latter case, the outcome is known for a range of environments for a given genotype, and the genotypic parameters are estimated by optimization procedures, thereupon considered traits for further genetic analyses (e.g., genome-wide association studies for diverse panels of genotypes). The latter application is also known as a heuristic approach or a reverse model application

RIDEV V2 was developed on the basis of RIDEV V1, a simpler tool developed in the 1990s at WARDA (now Africa Rice Center). New features in RIDEV V2 are micro-climate and TOA simulations, enabling the prediction of the temperature of the panicle at the time of anthesis; and a choice of several models for photoperiodism. The micro-climate model for floodwater and panicle temperature is empirical but was validated against a mechanistic heat balance model (IM2PACT, Tsukoba University, Japan).

RIDEV V2 is freely available to the public for non-commercial use. The purpose of the website is to provide a description, the source code and background information to potential users. A down-loadable installer package will be provided on this site at a later date.

Michael Dingkuhn, Cecile Julia, Jean-Christophe Soulie and Richard Pasco