Study: Selenium Treatment Shown to Protect Olive Trees Against Salt Stress

Olive trees grow­ing in saline con­di­tions expe­ri­ence salt stress, which causes meta­bolic and phys­i­o­log­i­cal prob­lems such as low water intake, reduced pho­to­syn­the­sis and nutri­tional imbal­ance.

However, a recent study by agri­cul­tural researchers at the University of Perugia, in Italy, shows that sele­nium bio­for­ti­fi­ca­tion can reduce stress lev­els in olive trees by increas­ing the water con­tent of the leaves, enhanc­ing pho­to­syn­the­sis and reduc­ing toxic effects.

“The results sug­gest a pos­i­tive effect of an appro­pri­ate amount of sele­nium, although with dif­fer­ent inten­si­ties depend­ing on the cul­ti­var, and the vigor of the olive tree pro­lif­er­ated shoots in vitro,” the study’s authors wrote.

While the olive tree is quite tol­er­ant to salin­ity, salt stress affects the plant by increas­ing the pro­duc­tion of reac­tive oxy­gen species in the long term, includ­ing hydroxyl rad­i­cal and hydro­gen per­ox­ide.

These com­pounds play a cen­tral role in oxida­tive cell dam­age and in extreme cir­cum­stances, the plants get dehy­drated and even­tu­ally die.

By under­tak­ing this study, the researchers wanted to inves­ti­gate, eval­u­ate and estab­lish the likely effects of sele­nium when admin­is­tered at dif­fer­ent con­cen­tra­tions to Arbequina trees expe­ri­enc­ing saline stress.

The sele­nium effects on the trees were stud­ied by mon­i­tor­ing phys­i­o­log­i­cal and bio­met­ric indices in rela­tion to the plant’s abil­ity to exchange gases, its growth and the water con­tent of the leaves.

In addi­tion, the researchers mon­i­tored bio-mol­e­c­u­lar para­me­ters includ­ing sele­nium and pro­line lev­els in the leaves and roots.

The study found that olive trees exposed to high lev­els of salin­ity had reduced foliar pho­to­syn­the­sis and height­ened sub-stom­atal con­cen­tra­tion of car­bon diox­ide.

Researchers attrib­uted the increase of CO2 in the plants to low pho­to­syn­the­sis result­ing from non-stom­ata effects and clo­sure of the stom­ata due to destruc­tion of the pho­to­sys­tem.

When the plants were treated with sele­nium – in the form of sodium sele­nate – there was a remarked reduc­tion of the neg­a­tive effects result­ing from the high lev­els of sodium chlo­ride. The olive trees expe­ri­enced a higher rate of pho­to­syn­the­sis, improved water con­tent in the leaves and bet­ter growth.

This is the first study demon­strat­ing that sele­nium has pro­tec­tive prop­er­ties against the neg­a­tive effects of sodium chlo­ride on olive trees.

However, the researchers con­cluded that more stud­ies need to be con­ducted in this area to deter­mine the effects of sele­nium bio­for­ti­fi­ca­tion on olive pro­duc­tion and oil qual­ity.

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