Effect of drought stress and selenium spraying on photosynthesis and antioxidant activity of spring barley | Učinek sušnega stresa in škropljenja s selenom na fotosintezo in antioksidativno aktivnost jarega ječmena

إنجليزي. This paper reports the effects of selenium (Se) application on some physiological characteristics of barley (Hordeum vulgare L. cv. Rihane-03) exposed to drought stress. Foliar application to barley at 30 g selenium ha-1, as sodium selenate, increased significantly shoot dry weight and relative water content in well-watered plants. A remarkable reduction in dry weight of water-stressed plants was associated with significant decrease in maximal efficiency of PSII (Fv/Fm), stomatal conductance (gs) and net CO2 assimilation rate (A). Activity of antioxidant enzymes was increased by drought stress significantly. Amounts of malondialdehyde (MDA) and hydrogen peroxide (H2O2) remained unchanged in Se-supplemented water-deficit plants obviously because of an efficient scavenging following significant enhancement of catalase (CAT) and glutathione peroxidase (GSH-Px) activities. These results indicate that an application of selenium was favorable for biomass accumulation of barley plants under well-watered conditions. However, it did not significantly affect dry matter accumulation under drought stress, but Se-supplemented water-deficit plants exhibited better protection from oxidative damage because of higher CAT and GSH-Px activities and lower level of lipid peroxidation. These results suggest that selenium application can improve antioxidant defense system under drought stress conditions, and it may be recommended for arid and semiarid regions.

السلوفينية. Članek poroča o učinku škropljenja s selenom na nekatere fiziološke značilnosti ječmena (Hordeum vulgare ‘Rihane-03’), ki je bil izpostavljen sušnemu stresu. Foliarna aplikacija selena 30 g Se ha-1, kot selenat je značilno povečala suho težo poganjkov in relativno vsebnost vode dobro zalivanih rastlin. Znatno zmanjšanje suhe teže rastlin v pomanjkanju vode je bilo povezano z značilnim zmanjšanjem maksimalne učinkovitosti PSII (Fv/Fm), stomatarne prevodnosti (gs) in neto asimilacije CO2 (A). Aktivnost antioksidativnih encimov se je v sušnem stresu značilno povečala. Količini malondialdehida (MDA) in vodikovega peroksida (H2O2) sta ostali nespremenjeni pri rastlinah tretiranih s Se pri sušnem stresu, kar je bila očitno posledica delovanja Se, ki se je kazala kot povečana aktivnost katalaze (CAT) in glutation peroksidaze (GSH-Px). Ti izsledki kažejo, da uporaba Se prispeva k povečanju biomase ječmena pri dobri preskrbi z vodo. Vsebnost suhe snovi se pri rastlinah tretiranih s Se ni bistveno povečala v razmerah sušnega stresa, vendar pa so se te rastline bolje zaščitile pred oksidativnimi poškodbami s povečano aktivnostjo CAT in GSH-Px in manjšo peroksidacijo lipidov. Rezultati kažejo, da uporaba Se izboljša antioksidativno obrambo rastlin pri sušnem stresu in bi njegovo uporabo v te namene priporočali v aridnih in semiaridnih območjih.