Abstract:With the seeds of Lycium ruthenicum as the experimental material, the neutral salt NaCl, Na2SO4 and the alkaline salt NaHCO3, Na2CO3 were simulated to form neutral compound salt L (1∶1∶0∶0), moderately basic compound salt M (1∶9∶9∶1) and severely basic compound salt H (9∶1∶1∶9) according to the proportion of alkaline salts from small to large, we used the Paper Germination experiment to study the effects of exogenous melatonine (0.1, 0.3, 0.5, 1.0 mmol/L) on seed germination and seedling growth of L. ruthenicum seeds under different saltalkali composition (L, M, H) and saltalkali concentration (50, 100, 200 mmol/L) combined stress. The results showed: (1) the growth phenotype of L. ruthenicum seedlings is obviously weakened with the increase of salinealkali concentration and alkaline salt proportion; Appropriate concentration of exogenous melatonine (0.1, 0.3, 0.5 mmol/L) could alleviate the damage of salinealkali stress on seedling growth to a certain extent, while excessive concentration of exogenous melatonine (1.0 mmol/L) will aggravate the damage. At the same time, the application of exogenous melatonine(MT) significantly increased the number of lateral roots of L. ruthenicum seedlings. (2) The germination process of L. ruthenicum seeds is closely related to salinealkali composition, salinealkali concentration and MT concentration. With the increase of the saltalkali concentration and the proportion of alkaline salt, the initial time of germination of L. ruthenicum seeds is delayed, and the total germination time is shortened; Applying an appropriate concentration of exogenous MT can advance the germination start time of L. ruthenicum seeds under salinealkali stress and prolong the total germination time. (3) In the L compound salt treatment, with the increase of the saltalkali stress concentration, the germination rate (GR), germination potential (GP), germination index (GI), vitality index (VI), shoot length (SL), root length (RL) all increase first and then decrease; In the M and H compound saltalkali treatments, all germination indexes showed a gradual decrease with the increase of the saltalkali stress concentration. (4) Exogenous MT has obvious “lowpromoting highsuppressing” phenomenon on the germination indexes of L. ruthenicum seeds, In the L compound salt, under the stress of 3 kinds of salt concentration, when the MT concentration is 0.1 and 0.3 mmol/L, it can promote GR, GP, GI, VI, SL and RL, and the comprehensive promotion effect of 0.1 mmol/L is the best, and when the MT concentration is 0.5 and 1.0 mmol/L, it has a inhibitory effect on GP, GR, GI and VI, when the MT concentration is 1.0 mmol/L, it has a inhibitory effect on SL and RL; Among the M and H compound saltalkali, under the stress of 3 kinds of saltalkali concentration, when the MT concentration is 0.1, 0.3, 0.5 mmol/L, it has a promoting effect on all indicators, and the comprehensive promotion effect of 0.3 mmol/L is the best, and when the MT concentration is 1.0 mmol/L, it has a inhibitory effect. Studies have shown that lowconcentration neutral compound salt treatment can promote seed germination and seedling growth of L. ruthenicum to a certain extent, while highconcentration neutral compound salt and moderate and severely alkaline compound salt have an inhibitory effect. Exogenous melatonin has a significant dose effect on the alleviation of seed germination and seedling growth of L. ruthenicum under saltalkali stress. When the melatonin concentration is 0.1 mmol/L, the comprehensive promotion effect on neutral complex salt stress is better, and melatonin at 0.3 mmol/L, it has the best promoting effect on moderate and severe alkaline complex salt stress.