Abstract: The study was designed to investigate the effects of spraying exogenous spermidine (0.25 mmol/L) on fruit yield, quality and volatile compounds in tomato cultivar Jinpengchaoguan. Plants were exposed to 75 mmol/L salinity-alkalinity stress c(NaCl):c(Na2SO4):c(NaHCO3):c(Na2CO3) = 1:9:9:1. Four treatments were performed: 0 mmol/L salinity-alkalinity plus 0 mmol/L Spd (CK), 0 mmol/L salinity-alkalinity plus 0.25 mmol/L Spd (CS), 75 mmol/L salinity-alkalinity plus 0 mmol/L Spd (S), and 75 mmol/L salinity-alkalinity plus 0.25 mmol/L Spd (SS). The results showed that applying 0.25 mmol/L Spd (SS) significantly improved fruit VC (P < 0.05), soluble sugar and lycopene contents and yields (P < 0.05). Under salinity-alkalinity stress the organic acid and nitrate contents were reduced significantly (P < 0.05). Headspace solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was used to analyze the volatile substances of tomato fruits in different treatments. Our results illustrated that salinity-alkalinity stress could decrease the total number of volatile substances and the relative contents of characteristic aroma compounds, and this effect could be mitigated by spraying Spd. Therefore, spraying Spd can reduce the adverse effects caused by salinity-alkalinity stress, resulting in improved fruit quality and aroma, and increased fruit yield.

Key words: salinity-alkalinity stress, spermidine, tomato, quality, volatile compounds