Sugars and sugar alcohols have their say in the regulation of flower senescence in Dianthus chinensis L

• Sucrose was the most effective sugar in increasing flower longevity of the isolated flowers of Dianthus chinensis.
• Increased protease activity resulted in the enhanced protein degradation leading to the senescence of this cut flower.
• Sugars showed a decline with senescence and phenols showed an upsurge with the onset of senescence.

An experiment was designed to determine the effect of various sugars and sugar alcohols on the longevity of the isolated flowers of Dianthus chinensis. Isolated flowers were harvested at brush stage (one day before anthesis) at 800 h and held in different test solutions viz. d-glucose, mannitol, inositol, sucrose and polyethylene glycol (PEG). A separate set of flowers held in distilled water was designated as control. The flowers held in sucrose showed an increment in the longevity of 5 days followed by 3 days in d-glucose, besides maintaining higher fresh & dry mass, water content and floral diameter. Conversely, decreased soluble sugar content was maintained in the samples from these two treatments. Flowers held in sucrose showed maximum content of amino acids in its tissue samples. Phenols showed a marginal increase with the progression in senescence from day 2 to day 5. Moreover, flowers held in polyethylene glycol showed higher content of total phenols which was marginally higher than the control and other treatments. Flowers held in d-glucose maintained maximum content of sugar fractions (total and reduced). Maximum not reducing sugar content was maintained in the flowers held in polyethylene glycol. Sugar fractions (total, reducing and non-reducing) showed a significant decrease as the senescence progressed from D2 to D5. The present study revealed that there is decrease in sugar content and increased protease activity in the early steps during the process of flower senescence in D. chinensis. Sucrose was found to be most important in D. chinensis followed by d-glucose. Besides polyethylene glycol was found to arrest flower opening in all the concentrations from 5 μM to 50 mM.