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The current survey aimed to study the effect of exogenous salicylic acid (SA) application on salinity stress of grapevine cv. ’Sultana’. The leaves of hydroponically cultivated grapes that were under 0, 75 and 150 mM salinity conditions treated with 0, 0.5, 1 and 1.5 mM SA and after two weeks, the factors such as Na+, K+, proline and MDA contents, leaf electrolyte leakage and enzymatic activities were measured. The results showed that all SA treatments were significantly effective at tolerance enhancement by reduction in Na+/K+ ratio, leaf electrolyte leakage, MDA and H2O2 values and promotion in proline content and the enzymatic activities (POD, APX, CAT and SOD) of grapes. These results indicated that SA application at salinity condition could be applied as a promising method for increasing the salinity tolerance of ‘Sultana’ grapes.
The use of natural and biodegradable material (such as fish flour) counteracts stress as cheaper and safer alternative for toxic chemicals (such as pesticides). The effect of calcium and fish flour (Ca and FF) (single or in combination) to improve plant tolerance against salt stress was studied. Sterilized mentha seeds were imbibed in each treatment: FF (10 g mL–1), Ca (1, 3%) applied alone and in Ca+FF-combination shaking for 24 h at 150 rpm. Changes in the antioxidants (carotenoids, phenolic, and flavonoid), enzymatic system (superoxidase – SOD, guaiacol-dependent peroxidase – GPX and phenylalanine ammonia-lyase – PAL) and lipid peroxidation levels of mentha seedlings were investigated under salt stress. It was suggested that Ca and/or FF had positive regulation effects on the key enzyme activities related to phenolic compounds biosynthesis and individual phenolic contents under salt stress. Additionally, the mentha plants developed from Ca+FF-combined pre-treatments showed better response to salinity than either Ca or FF single pretreatment. Suppression of salt injury by Ca+FF pre-treatment reduced the LPO levels, increased enzyme activities and promoted total flavonoid and phenolic contents. Ca+FF-combined pre-treatment of mentha seeds seem to be a reliable, not-expensive and easy procedure to enhance plant salt tolerance and to gain more biomass.
This study assessed the effects of different doses of ethephon and gibberellin A3 on germination and α- and β-amylase activity in Amaranthus caudatus seeds exposed to different levels of salt stress. NaCl at 25 and 50 mM only delayed germination; at 75, 100 and 125 mM it caused 50%, 90% and 99.5% inhibition of Amaranthus caudatus seed germination. Both ethephon and GA3 (0.01, 0.1, 0.3 mM) effectively counteracted inhibition of seed germination under salinity. The stimulatory effect of ethephon appeared earlier, and the seeds were more sensitive to ethephon than to GA3. Ethephon enabled seed germination in the presence of all NaCl concentrations (75, 100, 125 mM) even after 24 h. GA3 alleviated inhibition caused by 75 and 100 mM NaCl until 48 h and did not affect reduction of germination caused by NaCl at 125 mM. NaCl (100 mM) reduced α- and β-amylase activity and seed germination after 14 h, and enhanced α-amylase activity after 20 h, although germination was reduced. Ethephon and GA3 increased α- but not β-amylase activity under salt stress during the first 14 h of incubation
This study was conducted to determine the correlation between of salinity stress on growth and phenolic compounds in rice. It was observed that salinity stress caused a significant decrease in shoot lengths, fresh and dry weights of all rice varieties. Under salinity stress, changes of chemical contents also differed among phenolic compounds and rice cultivars. Total phenolics and flavonoids, and contents of vanillin and protocatechuic acid in tolerant varieties were strongly increased, whereas in contrast, they were markedly reduced in the susceptible cultivar. Ferulic acid and p-coumaric acid were detected only in tolerance rice. Vanillin and protocatechuic acid may play a role, but ferulic acid and p-coumaric acid may be much involved in the tolerant mechanism against salinity stress. Ferulic acid and p-coumaric acid and their derivatives are potent to be exploited as promising agents to reduce detrimental effects of salinity stress on rice production.
Endopolyploidy is a condition of a cell containing reduplicated genetic material in its nucleus. Cells with the nuclei of different ploidy levels are often present within a single polysomatic organism. Endoreduplication is thus a modified cell cycle that omits cytokinesis and leads to chromatin replication in the endopolyploid cells. This study aimed to research the effect of salinity on endopolyploidy of Trifolium pratense and T. repens. Both species are important pasture legumes and belong to the genus Fabaceae with the well documented endopolyploidy occurence. Endopolyploidy levels in the seedlings treated with 0, 30, 60, 90 and 120 mM NaCl were investigated by flow cytometry. The seedling organs were evaluated during three ontogeny stages. The cytometric data plotted on a histogram showed the presence of 2C-16C nuclei in T. pratense and 2C-8C in T. repens. The hypothesis that salinity induces additional endocycles was not confirmed. Our results show that the distribution of nuclei among ploidy levels does not differ markedly between the treatment groups and the control ones. Additionally, only minor changes were observed among the endoreduplication indexes (EI) of plant organs after exposure to various salt concentrations. Endopolyploidy patterns within the salt-treated seedlings during ontogeny are similar to the controls. We suggest that endopolyploidy in Trifolium species is a conserved genetic trait, rather than an adaptation to salinity stress. The analyses of the roots of T. pratense at stage III show that with the increased concentrations of NaCl the length of roots decreased, but no evident changes in endopolyploidy occured.
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