Chlorocholine chloride and paclobutrazol treatments promote carbohydrate accumulation in bulbs of Lilium Oriental hybrids 'Sorbonne'

The present study was to test the hypothesis that the plant growth retardants chlorocholine chloride (CCC) and paclobutrazol (PBZ) could improve the carbohydrate accumulation in lily bulbs by enhancing photosynthetic capacity and changing endogenous hormones. Plants of Lilium Oriental hybrids 'Sorbonne' were treated with a foliar spray of CCC or PBZ (both at 300 mg/L) solution, at six weeks after planting (6 WAP). The morphological parameters, endogenous hormone contents (gibberellic acid (GA), abscisic acid (ABA), and indole-3-acetic acid (IAA)), and carbohydrate contents were measured from 6 to 18 WAP, at 2-week intervals. The results showed that CCC increased the biomass of leaves and stems which might produce more photoassimilates available for transportation and utilization. However, PBZ treatment suppressed vegetative growth and favored photoassimilate transportation into bulbs. A slight delay of bud and anthesis formation was observed in both treated plants. CCC and PBZ treatments substantially enhanced the sucrose contents in leaves probably due to the increase of chlorophyll contents. Treatment with CCC or PBZ decreased GA but increased IAA contents in lily bulbs which might stimulate starch accumulation and formation of new scales. Our experiment suggested that CCC or PBZ treatment is an effective method to promote carbohydrate accumulation in lily bulbs.