Effects of L-arginine on Some Cytogenetical and Physiological Parameters of Allium cepa L. Seeds exposed to Salinity

In this study, L-arginine (Arg) effects on the seedling growth (fresh weight, radicle length and radicle number), seed germination, mitotic activity, chromosomal aberrations and micronucleus frequency in Allium cepa L. germinated in both salt stress and normal conditions were investigated. In only Arg medium, the radicle number of the seeds was partially reduced compared to the control seeds germinated in the distilled water medium, the fresh weight, radicle length and germination percentage indicated statistically the same values as the control. Besides, the mitotic index in the root tip meristems of A. cepa seeds germinated in the Arg medium alone showed a decrease compared to the control seeds germinated in the distilled water medium, whereas the chromosomal aberrations exhibited a significant increase compared to the control. Moreover, the micronucleus formation increased compared to the control. On the other hand, salt stress significantly inhibited the seedling growth and seed germination of A. cepa. In addition, it significantly reduced the mitotic index in the root tip meristems of the seeds and increased the number of chromosomal abnormalities and micronucleus frequency, which is the simplest indicator and the most effective of cytological damage. Nonetheless, the inhibitive effect of salt on the micronucleus formation, mitotic activity, seedling growth, seed germination and chromosomal aberrations significantly decreased with the application of L-arginine.