Effect of foliar-applied silicon on photochemistry, antioxidant capacity and growth in maize plants subjected to chilling stress | Učinek foliarnega dodajanja silicija na fotokemično in antioksidacijsko učinkovitost ter rast koruze v razmerah hladnega stresa

anglais. Low temperature is one of the major adverse climatic factors that suppress plant growth and sustainable agricultural development. In these climate conditions, silicon (Si) can mitigate various abiotic stresses including low temperature. In this study, the roles of foliar-applied silicon (10 mM potassium metasilicate) in enhancing tolerance to chilling stress were investigated in maize (Zea mays ‘Fajr’) plants. The low temperature stress caused significant reduction of plant growth and relative water content; however, Si ameliorated these effects. Si supply in maize exhibited a significantly positive effect on accumulation of free amino acids, and reduced the necrotic leaf area. The decrease in maximum quantum yield of PSII (Fv/Fm) was reversible during recovery, but not in the non-Si-treated leaves. This can be explained by enhancement of protective pigments; carotenoid and anthocyanin leading to the protection of PSII from damage. Additionally, analysis of OJIP transients revealed that Si reduced cold damaging effect on performance index (PIabs) and Fv/Fm through improvement of excitation energy trapping (TR0/CS) and electron transport (ET0/CS) per excited cross-section of leaf. The malondialdehyde (MDA) concentration, which was significantly increased under chilling stress, was decreased by Si. The reduced glutathione and ascorbate concentrations were higher in Si-treated plants as compared to those without application of Si under chilling stress. These results indicated that Si could enhance the chilling stress tolerance of maize plants through improving the biomass accumulation, maintaining a high level of glutathione, ascorbic acid, protein, protective pigments, and enhancing the photochemical reactions. This study also suggests that the foliar-applied Si increases recovery ability from chilling injury.

slovène. Nizka temperatura je eden izmed glavnih neugodnih klimatskih dejavnikov, ki zavira rast rastlin in trajnostni razvoj kmetijstva.V takšnih klimatskih razmerah lahko silicij oblaži abiotski stress vključno z učinki nizke temperature. V tej raziskavi je bila preučevana vloga foliarnega dodajanja Si (10 mM kalijevega metasilikata) pri povečevanju odpornosti koruze (Zea mays ‘Fajr’) na hladni stres. Stres zaradi nizkih temperature je značilno zmanjšal rast in vsebnost vode v rastlinah, kar je dodajanje Si oblažilo. Dodatek silicija je sprožil v koruzi značilne pozitivne učinke v kopičenju prostih amino kislin in v zmanjšanju nekrotičnosti listov. Zmanjšanje v fotokemični učinkovitosti PS II (Fv/Fm) je bilo povratno med okrevanjem, vendar ne pri rastlinah, ki niso bile tretirane s silicijem. To bi lahko razložili s povečanjem vsebnosti zaščitnih pigmentov karotenoidov in antocianinov, kar vodi v zaščito PSII pred poškodbami. Dodatno so analize prehodne fluorescence klorofila a (OJIP) odkrile, da je dodatek Si zmanjšal učinek poškodb zaradi hlada na fotosintetski elektronski transport (PIabs in Fv/Fm) preko boljšega prestrezanja ekscitacijske energije (TR0/CS) in boljšega elektronskega transporta (ET0/CS) na presek ekscitiranega lista. Hladni stres je povzročil poškodbe membran, kar se je odrazilo v povečani koncentraciji malondialdehida. V rastlinah tretiranih s Si koncentracija malondialdehide ni dosegla ravni rastlin, izpostavljenih hladnem stresu. Koncentracije reduciranega glutationa in askorbata so bile večje v rastlinah, tretiranih s Si v razmerah hladnega stresa v primerjavi s tistimi, ki s silicijem niso bile tretirane. Ti rezultati nakazujejo, da bi lahko silicij povečal odpornost na hladni stres pri koruzi z izboljšanjem prirastka biomase, vzdrževanjem visoke ravni glutationa, askorbinske kisline, beljakovin, zaščitnih pigmentov in v povečevanju fotokemičnih reakcij. Raziskava nakazuje, da foliarno dodajanje silicija povečuje sposobnost okrevanja iz od hlada nastalih poškodb.