Effects of PEG and NaCl stress on seed germination,seedling growth of Melilotus accession

In this study, five high performing Melilotus accessions were evaluated seed germination and seedling growth under different PEG and NaCl treatment, by determination germination percentage, germination energy, the radicle and seedling length, germination index, vigor index. The analysis of Fuzzy Mathematics Based Comprehensive Evaluation method is used to investigate drought and salt tolerance differences among accessions. The results shows that: 1) High osmotic potential (≥-0.3 MPa) significantly(P<0.05)increased seed germination in all accessions compared to the control. In addition, the radicle and seedling growth of PI595335, MO-LX04, PI595388 was significantly reduced but significantly(P<0.05) increased for Ames19257 and PI593234 at high osmotic potential (≥- 0.3 MPa). At low osmotic potential(≤-0.9 MPa), all seeds germination and seedling growth were significantly(P<0.05)reduced. 2) Seedling growth was significantly influenced under different levels of NaCl treatment on all accessions. Seed germination was significantly(P<0.05)increased at low concertation of NaCl(≤100 mmol·L-1). 3) The analysis using Fuzzy Mathematics Based Comprehensive Evaluation showed that: the drought tolerance of five Melilotus accessions in seed germination period as follows: Ames19257>PI593234>MO-LX04>PI595335>PI595388, salt resistance is PI593234>Ames19257>PI595388>MO-LX04>PI595335. The performance of Ames19257 and PI593234 were significantly better than the other three Melilotus accessions in the drought and salt tolerance test, and therefore they are good genetic materials for the future breedingprograms in the northwest of China.