Growth kinetics of Marquis wheat. VII. Dependence on photoperiod and light compensation point in vegetative phase

Abstract

The maximum rate coefficients for the vegetative phase of growth in dry weight of shoots and roots were independent of the photoperiod in plants grown at six different light intensities of 12- or24-h duration at 20 °C. The strict dependence of plant growth on only the total daily incident radiant energy was proved by the superposition of hyperbolic plots of growth coefficients obtained for five different photoperiods and for the different light intensities. Root growth was very sensitive to photoperiod at moderate light intensity. Growth kinetics changed from first to zero order in plant dry weight at a 12-h photoperiod with a light intensity of 150 ft-c (3750 ergs cm−2 s−1) depending on pretreatment. The light compensation point of plant growth occurred at16 × 107 ergs cm−2 day−1; that for shoots was lower, and that for roots was higher.