PHYTOCHROME REGULATION OF MORPHOGENESIS IN GREEN PLANTS: FROM THE BELTSVILLE SPECTROGRAPH TO COLORED MULCH IN THE FIELD*

Development of the theory and use of photon ratios reflected from colored mulches to regulate plant morphogenesis in the field utilized information obtained on the Beltsville Spectrograph, in controlled environments and in field plant spacing studies. An upwardly reflected far-red to red (FR/R) ratio higher than the ratio in incoming sunlight resulted in larger shoots and a higher shoot/root biomass ratio. A reflected FR/R ratio lower than the ratio in incoming sunlight resulted in larger roots and a lower shoot/root biomass ratio.