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bioRxiv · 10.1101/2020.11.29.402628

Crop-photoperiodism model 2.0 for the panicle-initiation date of sorghum and rice that includes daily changes in sunrise and sunset times

Clerget, B.·Sidibe, M.·Bueno, C. S.·Trouche, G.·Chantereau, J.·Grenier, C.·Kawakata, T.·Domingo, A. J.·Layaoen, H. L.·Palacios, N. G.·Bernal, J. H.
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Abstract

Background and AimsDaylength determines flowering dates. However, questions remain regarding flowering dates in the natural environment, such as the synchronous flowering of plants sown simultaneously at highly contrasting latitudes. The daily change in sunrise and sunset times is the cue for the flowering of trees and for the synchronisation moulting in birds at the equator. Sunrise and sunset also synchronise the cell circadian clock, which is involved in the regulation of flowering. The goal of this study was to update the photoperiodism model with knowledge acquired since its conception. MethodsA large dataset was gathered, including four 2-year series of monthly sowings of 28 sorghum varieties in Mali and two 1-year series of monthly sowings of eight rice varieties in the Philippines to compare with previously published monthly sowings in Japan and Malaysia, and data from sorghum breeders in France, Nicaragua, and Colombia. An additive linear model of the duration in days to panicle initiation (PI) using day length and daily changes in sunrise and sunset times was implemented. Key ResultsSimultaneous with the phyllochron, the duration to PI of field crops acclimated to the mean temperature at seedling emergence within the usual range of mean cropping temperatures. A unique additive linear model combining daylength and daily changes in sunrise and sunset hours was accurately fitted for any type of response in the duration to PI to the sowing date without any temperature input. Once calibrated on a complete and an incomplete monthly sowing series at two tropical latitudes, the model accurately predicted the duration to PI of the concerned varieties from the equatorial to the temperate zone. ConclusionsThe results of the updated photoperiodism model strongly supported the hypothesis that photoperiodism could be a combined response to day length and daily changes in sunrise and sunset times.

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Clerget, B., Sidibe, M., Bueno, C. S., Trouche, G., Chantereau, J., Grenier, C., Kawakata, T., Domingo, A. J., Layaoen, H. L., Palacios, N. G., Bernal, J. H.. 2020-11-29. Crop-photoperiodism model 2.0 for the panicle-initiation date of sorghum and rice that includes daily changes in sunrise and sunset times. https://doi.org/10.1101/2020.11.29.402628

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