Identification of physiological maturity in sunflowers (Helianthus annuus)

Abstract

The hypothesis that floret abscission coincides with physiological maturity in sunflowers (Helianthus annuus) was examined in experiments involving 10 and 33 plants respectively. Time courses of achene dry weight accumulation were established for individual capitula to determine attainment of maximum achene dry weight, or physiological maturity. No difference was found in either experiment (P > 0.05) between the mean date for physiological maturity and mean dates for any of three phases of floret abscission, the mid-point between first and last floret abscission exhibiting the closest association with maturity. Time courses of floret abscission were subsequently used to characterize physiological maturity in a crop of 100 plants.