Effects of a nitric oxide donor and nitric oxide scavengers on <Emphasis Type="Italic">Sorbus pohuashanensis</Emphasis> embryo germination

The effects of an exogenous nitric oxide donor (sodium nitroprusside, SNP), a NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxode (PTIO) and carboxy-PTIO potassium salt (cPTIO) on the embryo germination of Sorbus pohuashanensis were studied in a petri dish test. SNP at 0.5–5 mmol L^?1 increased germination percentage, mean time to germination, germination index and germination energy compared with the control to different degrees. Treatment with 2 mmol L^?1 SNP improved germination most significantly; embryo germination percentage for mother tree 1 (91.11%) and mother tree 2 (64.44%) were much higher than the control. In addition, excessive SNP levels did not enhance embryo germination. Combined treatment with SNP and an NO scavenger delayed embryo germination. Treatment with cPTIO inhibited embryo germination; germination percentage was 42.22% and was lower than that of the control. These results show that low concentrations of exogenous NO can enhance the embryo germination of S. pohuashanensis, providing a simple, effective way for promoting germination of S. pohuashanensis.