Bioactive substances enhance the germination and salt resistance of melon ( <i>Cucumis melo</i> L.) seeds

ABSTRACT This experiment aimed to explore the effects of bioactive substances such as alginate (seaweed extract) (SW), potassium humate (humic acid) (HA), diethyl aminoethyl hexanoate (DA-6) and brassinolide (BR) on the germination and salt resistance of melon seeds, and to optimise their appropriate concentrations and ratios. The simulated salt stress environment was irrigated with a 100 mmol · L −1 NaCl solution. Treatment groups with different concentrations of SW, HA, DA-6 and BR were set up, and a completely blank control group (CK) was set up. The optimal concentrations were SW 1000 mg · L −1 , DA-6 10 mg · L −1 , HA 50 mg · L −1 and BR 0.2 mg · L −1 . Among them, SW treatment can maximise the germination index, with an average of 26.7. DA-6 had the best effect on promoting the growth of the radicle and the most significant promotive effect, with embryonic root length and hypocotyl length reaching 95.0 mm and 11.8 mm, respectively. HA can also effectively improve seed germination rate and vigour index, with mean values of 91.5% and 217.4%, respectively. BR can effectively improve the vigour index of seeds, reaching 241.6. All tested bioactive substances significantly improved the salt resistance of melon seeds, and among them, alginate showed the most significant effect compared with the control group. Not only did the main root length increase, but the number of lateral roots also significantly increased. When the concentration of SW reached 1000 mg · L −1 , vigour index and radicle length showed significant differences compared with the control, thereby enhancing its salt resistance.