Influence of exogenous polyamines on antioxidant defence and essential oil production in valerian (Valeriana officinalis L.) plants under drought stress | Vpliv dodajanja poliaminov na antioksidativno obrambo in produkcijo eteričnih olj pri zdravilni špajki (Valeriana officinalis L.) v razmerah sušnega stresa

anglais. The objective of this study was to determine the effects of foliar application of polyamines (PAs) on antioxidant defence and essential oil production of valerian (Valeriana officinalis L.) grown under different drought stress treatments (100, 70, 50 and 30% available water content). This study was carried out using pots in greenhouse condition. Drought–stressed valerian seedlings were sprayed with 1 mM concentration of each putrescine (Put), spermidine (Spd) and spermine (Spm). The results showed that drought stress significantly affected most biochemical characteristics of valerian plants. Characteristics including leaf relative water content, chlorophyll a and b contents were decreased, while carotenoids and electrolyte leakage were increased with the increase of water stress. In this research, defensive characteristics comprising proline content, soluble sugars, catalase, and ascorbate peroxidase were increased followed by drought stress to ameliorate the adverse effect of it.  Results revealed that foliar application of Spd and Spm provoked the antioxidant enzymes activity as well as proline accumulation in valerian which alleviate the membrane damages. Consequently, Spd and Spm increased photosynthetic pigments which act as energy supply for plant growth and production. Here, putrescine had detrimental effects on CAT activity and Chl a content. Albeit, PAs presented remarkable effects under moderate drought stress condition but it showed reverse trends in severe drought stress condition.  In terms of quantity and quality yield, drought stress reduced root growth but increased the concentration of essential oils. PAs are able to alleviate water deficit-induced diminish root growth. These results suggest that in moderate drought stress, growers can use PAs to increase productivity valerian.

slovène. Namen raziskave je bil določiti učinke foliarnega dodajanja poliaminov (PAs) na antioksidacijsko obrambo in tvorbo eteričnih olj pri zdravilni špajki (Valeriana officinalis L.) gojeni pri različni oskrbi z vodo (100, 70, 50 in 30 % vsebnosti razpoložljive vode). Raziskava je bile izvedena kot lončni poskus v rastlinjaku. Sadike špajke v sušnem stresu so bile škropljene z 1 mM raztopino putrescina (Put), spermidina (Spd) in spermina (Spm). Rezultati so pokazali, da je sušni stres značilno vplival na večino analiziranih biokemičnih parametrov v zdravilni špajki. Parametri kot so relativna vsebnost vode, vsebnost klorofila a in b so se zmanjšali, medtem ko sta se vsebnost karotenoidov in iztok elektrolitov povečala z večanjem sušnega stresa. Obrambni mehanizmi rastline, ki obsegajo vsebnost prolina, topne sladkorje, aktivnost katalaze in askorbat peroksidaze so se z večanjem sušnega stresa povečali, da bi omilili škodljive učinke stresa. Rezultati so pokazali, da je foliarno dodajanje Spd in Spm sprožilo antioksidacijsko aktivnost encimov in akumulacijo prolina v zdravilni špajki, kar je zmanjšalo poškodbe membrane. Posledično sta Spd in Spm povečala vsebnost fotosinteznih barvil, ki rastlini omogočajo oskrbo z energijo za rast in produkcijo. Dodajanje putrescina je imelo negativen učinek na aktivnost katalaze (CAT) in vsebnost klorofila a. Pozitivni učinki dodajanja poliaminov so bili opazni le v razmerah zmernega sušnega stresa in so dobili nasproten trend ob njegovi zaostritvi. Z vidika kakovosti in količine pridelka je sušni stres zmanjšal rast korenin, a povečal vsebnost eteričnih olj. Poliamini lahko oblažijo zmanjšano rast korenin, ki jo povzroča pomanjkanje vode. Ti rezultati nakazujejo, da lahko pridelovalci v razmerah zmernega sušnega stresa z dodatkom poliaminov povečajo pridelek zdravilne špajke.