Effects of Iso-Osmotic Potential of NaCl and PEG6000 Solutions on Germination and Initial Seedling Growth of Sweet White Lupin (Lupinus albus L)

Sweet white lupin has a growing importance as a staple crop due to its rich protein and mineral content. Investigation of unfavorable environmental conditions at the seedling stage is critical for understanding and overcoming the challenges during germination and initial growth. In this study, the effects of salt and drought stress were investigated upon induction of NaCl and PEG6000 osmotic agents at iso-osmotic potential (0, -0.3 and -0.6 MPa) on seed germination and initial seedling growth in sweet white lupin (Lupinus albus L.). The research was carried out for 21 days under laboratory conditions according to a completely randomized plot design with 4 replicates. In order to assess the growth upon stress, germination percentage, mean germination time, germination rate index, shoot and root length, root/shoot length, shoot and root fresh weight, shoot and root dry weight, shoot and root dry matter content, root/shoot dry matter content, shoot and root water content and seedling vigor index parameters were measured. The results demonstrated that NaCl and PEG6000 solutions applied at the same osmotic potential had statistically significant effects on the measured germination and growth parameters. PEG6000 treatments at the same osmotic potential had more adverse effects on germination and initial seedling growth than NaCl treatments. In addition, shoot growth was more adversely affected than root growth in PEG6000 and NaCl treatments. The germination was limited in -0.6 MPa PEG6000 treatment and no subsequent seedling growth was observed. In this study, we documented that the white lupine's tolerance to drought during germination and initial seedling growth periods was lower than salinity at the same iso-osmotic potential and saline and arid soils showing an osmotic water potential of -0.6 MPa (12.7 dS m-1 EC and 22% PEG6000) are inhibitory for lupin germination and growth. This study lays the ground for further physiological and molecular studies on the effects of salt and osmotic stress on white lupins.