A whole-system reconsideration of paradigms about photoperiod and temperature control of crop yield.

Effects by photoperiod gene(s) and daylength on crop yield and its three major physiological components (aerial biomass, harvest index, and days to harvest maturity) are reviewed for bean (Phaseolus vulgaris L.) and peanut (Arachis hypogaea L.). In these plus many other cited crops, photoperiod sensitive gene(s) delay days to flowering and/or days to maturity in non-promotive daylength while simultaneously lowering the harvest index. Thus, for many crops, earlier maturity is associated with higher harvest index, and/or it has been shown that photoperiod gene(s) control partitioning of photosynthate toward reproductive growth versus toward competitive partitioning to continued vegetative growth. Our conclusion is that photoperiod gene control over this partitioning precedes and is causal of the photoperiodgene control over days to flowering and maturity. This implies shifts from commonly accepted paradigms about effects by photoperiod and about breeding for higher yield. These paradigm shifts suggest more efficient ways to breed for cultivar adaption to the specific growing season duration and environment of each geographical site and for higher crop yield.