The effect of salinity on hypocotyl and radicle length of Arabidopsis thaliana

Abstract

To determine the effect of salinity on the hypocotyl and radicle length following germination of wild type Arabidopsis thaliana, we grew A. thaliana in three different concentrations of NaCl: tap water control, 0.01 mM, and 0.02 mM. The growth was measured by hypocotyl and radicle length. The results of our experiment indicated a mean growth of 0.737 mm ± 0.286 mm for the control treatment, 0.170 mm ± 0.254 mm in low salt treatment, and 0.242 mm ± 0.051 mm in high salt treatment on Day 5 of the experiment. The control experienced significantly more growth than the high salt treatment, as well as significantly more growth than the low salt treatment over the first five days of the experiment. Therefore, we are able to reject our null hypothesis. On Day 9, we found the growth to be 0.709 mm ± 0.077 mm for the control treatment, 1.019 mm ± 0.660 mm for the low salt treatment, and 1.563 mm ± 0.065 mm for the high salt treatment. These results show that the high salt treatment experienced significantly more growth than the control treatment during the final four days of the experiment. This is not consistent with previous studies in the field. This leads us to conclude that salt concentration does have a delaying effect on germination; however, after an initial period of stunted growth, the salt may enhance seedling growth. A likely explanation for the enhanced seedling growth is the production of salicylic acid by the seedlings, which is known to stimulate germination and have increased production in high salinity, as well as the production of proline, an amino acid, which increases salt tolerance in the organism following an applied salt stress.