Effect of nitric oxide on dormancy release in bulbs of Oriental lily (Lilium orientalis) 'Siberia'

Nitric oxide (NO) is an essential endogenous plant signalling molecule involved in a wide range of plant developmental processes. To investigate the effect of NO on breaking dormancy in bulbs, bulbs of Oriental lily (Lilium orientalis) 'Siberia' were treated with various concentration of the NO donor, sodium nitroprusside (SNP; 0.0, 1.0, 3.0, or 5.0 mM). The results showed that the effect of NO was dose-dependent, with the maximum biological response at 1.0 mM SNP. When applied exogenously, the 1.0 mM SNP treatment reduced the time required to release dormancy in Oriental lily bulbs. Meanwhile, 1.0 mM SNP significantly increased the shoot length: bulb height ratio. In addition, 1.0 mM SNP significantly lowered starch concentrations and increased water soluble carbohydrate (WSC) and reducing sugar concentrations. These results indicate that NO treatment, at the correct dose, reduced the time required to release dormancy in bulbs by accelerating the degradation of starch and increasing the accumulation of WSC and reducing sugars in Oriental lily bulbs.