Improving rhizome yield and quality of Paris polyphylla through gibberellic acid-induced retardation of senescence of aerial parts.

Senescence in perennials has not been extensively studied compared to that in annual plants, and the effects of delaying senescence on plant biomass and metabolic features in herbaceous perennials has also been poorly reported. We recently examined the effects of gibberellin A(3) (GA(3)) on senescence of aerial parts of Paris polyphylla, which characterize the metabolic changes associated with senescence, and found antagonistic effects of GA and abscisic acid during this process. Rhizome yield and quality (saponin content) of Paris polyphylla were both improved by GA(3)-induced retardation of senescence. We propose that GA(3)-induced retardation of senescence increases green leaf area and prolongs the duration of photosynthesis, leading to increased rhizome yield. The increased saponin accumulation in GA(3)-treated plants may be explained by the longer growth phase and ensuing increased environmental stress.