The influence of chloride salinization on seeds germination and seedlings growth of Brassica napus L..

Rape (Brassica napus L.) has a grate practical interest. This plant widely used not only in food industry, but in technical production. The most common negative abiotic factor is a solinization of soil, which takes 25 percents of all soils of the world. Accumulation of salt in soil may lead to yield reduction, and, as a result, to significant economic losses. The influence of different concentration of NaCl (from 50 to 200 mM) on rape seedlings germination and morphogenesis in darkness were researched. Percentage of germinated seeds and growth rates (the length of hypocotyl and root) were analyzed on 3,5 and 7th day after germination under saline conditions.Under salt stress the suppression of seeds germination and inhibition of axial organs elongation were observed. The negative effect of short salinity (3,5 days) were more pronounced than under long-term salinity (7 days). The hypocotyls of rape seedlings were most sensitive to short salt action. In this case the inhibition of hypocotyl growth were observed under 50 mM NaCl. Also, the roots growth inhibition was notedonly under higher salt concentration (75 and 100 mM). Elongation of salt action to 7 days significantly changed the picture, because in this case the root growth of the rape seedlings was inhibited under 50 mM, while the growth inhibition of hypocotyls was detected under 125mM. It means, that primarily damaged the root system and afterwards the aerial organs under long-term salinity. At the same time, the process of seeds germination was sufficiently resistant to salinity. Expressed inhibition of germination was showed under 100-175 NaCl. The quantity of germinated seeds under long-term salinity (7 days) at a wide range of concentrations NaCl (100-175 mM) increased. On this basis we can conclude that salt presence in the medium only slowed the seeds germination and didn't cause it death in the early days of impact of salt. However, under 200 mM the seeds germination was completely suppressed. So, the seeds germination process was more salt-tolerant than hypocotyl and root system growth process. Also, the rape seedlings reaction on different salt concentrations characterized by the organ specificity. Decrease of inhibition influence of NaCl under long-term salinity, probably connected with adaptation of plants and with creation of protective mechanisms and improvement of their salt-tolerance.

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