Evaluation of salinity tolerance in lycopersicon species using in vitro culture test

To obtain the fundamental data useful for breeding salt tolerant tomatoes, two accessions of Lycopersicon pimpinellifoliurn(PI365916, PI279373), two accessions of L. glandulosum(PI126440, PI126434), one accession of L. hirsutum(PI134417), three accessions of L. peruvianum(PI390664, PI126434, PI128655), one accession of L. parviflorum(PI390677), and one accession of L. esculentum(PI370072) were evaluated for their potential in salinity tolerance utilizing in vitro culture system. Salt resistance or sensitivity was assessed by measuring germination rate and seedling growth on the basis of shoot and root length and dry weight of seedlings. Three accessions, PI128655(L. peruvianum), PI126440(L. glandulosum), and PI126434(L. glandulosum) appeared to have low sensitivity to salt stress relative to all other accessions, showing a lower decrease in germination and seedling growth rate even under highly salinity conditions, whereas PI365916(L. pimpinellifolium), PI134417(L. hirsutum), and PI390677(L. parviflorum) were considered to be highly sensitive genotypes. The accession PI390677 was unique because of its extreme susceptibility to salt stress. The remaining accessions PI126431(L. peruvianum), PI390665(L. peruvianum), PI370072(L. esculentum), and PI279373(L. pimpinellifolium) were ranked as moderately tolerant. Though seedling growth and germination rates in almost all the accessions decreased as the salt level increased to EC10, seedlings from three accessions, PI126440, PI128655, and PI390655 showed rapid increases in their root length by 458%, 360%, and 242%, respectively in comparison with the control. Our results demonstrated that there were considerable vaiabilities in salt tolerance among accessions of Lycopersicon species.