Modeling and validation of high-temperature induced spikelet sterility in rice

•A model for predicting spikelet sterility by high temperature was constructed.•Heading date of panicles followed Poisson probability distribution.•Flowering date and time of spikelets on a panicle followed normal distribution.•Fertility decreased logistically with temperature rise at meiosis and flowering.•Model integrating the above equations well predicted the field spikelet sterility. Spikelet sterility due to heat stress during reproductive stage would be one of the prominent factors to reduce rice yield under the projected global warming climate. A simulation model that was comprised of equations to estimate the probability distributions of heading date of panicles in the field, flowering date of spikelets on a panicle, and flowering time of spikelets during the day time and the two sterility response functions to the temperature on the day of meiosis and at the flowering time of a spikelet was constructed, calibrated, and validated to predict high-temperature induced spikelet sterility in rice. The model was calibrated and validated against the data collected from a series of experiments conducted in the plastic houses controlling the temperature to ambient, ambient+1.5°C, ambient+3.0°C, ambient+5.0°C, and ambient+7.0°C in 2009 and 2010. Heading, flowering habit, and spikelet sterility of rice exposed to different temperatures during two periods from 20 days before heading and initial heading to 20 days after heading were recorded on panicle basis for model calibration. For model validation spikelet sterility data were collected on hill (pot) basis from rice plants exposed to different temperatures from transiting to maturity in 2009 and 2010. The heading of panicle reached peak on four to six days after and lasted until 12 days after initial heading and the heading date distribution of panicles was well fitted to Poisson's equation. The flowering peak of spikelets on a panicle occurred at about 5 days after heading and lasted 11 days regardless of temperature and cultivars and the flowering distribution was well fitted to the normal distribution function. The anthesis in a day started from 8:00h, reached peak around 11:00h, and lasted until 15:00h regardless of temperature treatments, the flowering peak being a little earlier in a japonica cultivar “Hwaseongbyeo” than in a Tongil type one “Dasanbyeo”. The flower opening time followed the normal distribution with standard deviation of about one hour. The fertility responses to high temperature on th