Physiological aspects of willows (Salix spp.) in citric acid assisted phytoremediation of cadmium

Abstract

<p>U radu je analiziran&nbsp; uticaj limunske kiseline na morfolo&scaron;ke, fiziolo&scaron;ke i&nbsp; biohemijske<br />karakteristike&nbsp; odabranih&nbsp; klonova&nbsp; vrba&nbsp; (Salix&nbsp; spp.)&nbsp; gajenih&nbsp; u&nbsp; zemlji&scaron;tu&nbsp; umereno zagađenom&nbsp; kadmijumom&nbsp; (Cd).&nbsp; Definisanjem&nbsp; parametara&nbsp; akumulacije,&nbsp; otpornosti&nbsp; i tolerantnosti različitih klonova vrba na prisustvo kadmijuma u podlozi, kao i uspe&scaron;nosti primene&nbsp; limunske&nbsp; kiseline&nbsp; kao&nbsp; helatora&nbsp; u&nbsp; procesu&nbsp; asistirane&nbsp; fitoremedijacije,&nbsp; mogao&nbsp; bi se&nbsp; identifikovati&nbsp; klon&nbsp; (ili&nbsp; klonovi)&nbsp; pogodan&nbsp; za&nbsp; dekontaminaciju&nbsp; zemlji&scaron;ta&nbsp; zagađenog kadmijumom. Da&nbsp; bi&nbsp; se&nbsp; postigao&nbsp; cilj&nbsp; istraživanja biljke su gajene u polu-kontrolisanim uslovima tokom 3 meseca. Eksperiment je podeljen u dve faze (dve godine istraživanja),zasnovane&nbsp; na&nbsp; razlikama&nbsp; u&nbsp; metodolo&scaron;kom&nbsp; pristupu.&nbsp; Tokom&nbsp; prve&nbsp; godine&nbsp; limunska kiselina je dodata jednom, dok je tokom druge druge godine aplikacija ovog helatora vr&scaron;ena&nbsp; u&nbsp; tri&nbsp; ponavljanja.&nbsp; U&nbsp; radu&nbsp; je&nbsp; analizaran&nbsp; sadržaj&nbsp; i&nbsp; distribucija&nbsp; Cd&nbsp; u&nbsp; zemlji&scaron;tu&nbsp; i<br />različitim&nbsp; biljnim&nbsp; organima&nbsp; (koren,&nbsp; izdanak,&nbsp; mladi&nbsp; i&nbsp; stari&nbsp; listovi);&nbsp; uticaj&nbsp; Cd i&nbsp; limunske kiseline na morfometrijske parametre: visina i prečnik izdanka, masa i povr&scaron;ina listova, broj&nbsp; listova,&nbsp; masa&nbsp; i&nbsp; zapremina&nbsp; korena;&nbsp; na&nbsp; fotosintetičke&nbsp; karakteristike:&nbsp; intenzitet fotosinteze,&nbsp; intenzitet&nbsp; transpiracije,&nbsp; stomatalnu&nbsp; provodljivost,&nbsp; intercelularnu koncentraciju&nbsp; CO2,&nbsp; efikasnost&nbsp; kori&scaron;ćenja&nbsp; vode,&nbsp; koncentraciju&nbsp; fotosintetičkih&nbsp; pigmenata; na mineralnu ishranu i distribuciju makronutrijenata u biljkama (sadržaj azota, fosfora i kalijuma);&nbsp; na&nbsp; sadržaj&nbsp; aminokiseline&nbsp; prolina&nbsp; i&nbsp; cisteina;&nbsp; na&nbsp; aktivnost&nbsp; antioksidativnih enzima&nbsp; (katalaza,&nbsp; askorbat-peroksidaza,&nbsp; gvajakol-peroksidaza),&nbsp; kao&nbsp; neezmiskih antioksidanata poput sadržaja redukovanog glutationa i tiola. Dobijeni&nbsp; rezultati&nbsp; su&nbsp; ukazali&nbsp; na&nbsp; genotipsku&nbsp; specifičnost&nbsp; analiziranih&nbsp; klonova&nbsp; vrba&nbsp; u procesu&nbsp; fitoremedijacije&nbsp; u&nbsp; zavisnosti&nbsp; od&nbsp; primenjenog&nbsp; tretmana,&nbsp; doze&nbsp; Cd&nbsp; i&nbsp; prisustva limunske kiseline. Toksično dejstvo nije bilo jasno uočljivo na morfolo&scaron;kom nivou, dok su&nbsp; primenjeni&nbsp; tretmani&nbsp; signifikantno&nbsp; uticali&nbsp; na&nbsp; fiziolo&scaron;ko-biohemijske&nbsp; procese&nbsp; u biljkama.&nbsp; Sa&nbsp; povećanjem&nbsp; sadržaja&nbsp; Cd&nbsp; u&nbsp; biljkama&nbsp; je&nbsp; utvrđena&nbsp; tendencija&nbsp; smanjenja intenziteta fotosinteze, transpiracije, kao i efikasnosti&nbsp; kor&scaron;ćenja vode, dok je primena limunske&nbsp; kiseline&nbsp; ublažila&nbsp; &scaron;tetan&nbsp; efekat&nbsp; ovog&nbsp; te&scaron;kog&nbsp; metala,&nbsp; &scaron;to&nbsp; je&nbsp; registrovano&nbsp; na<br />kombinovanim tretmanima.&nbsp; Kao odgovor na akumulaciju Cd u biljnom tkivu utvrđena<br />je&nbsp; promena&nbsp; aktivnosti&nbsp; antioksidativnih&nbsp; enzima,&nbsp; kao&nbsp; i&nbsp; neezimskih&nbsp; komponenti<br />odbrambenog&nbsp; sistema&nbsp; za&scaron;tite.&nbsp; Pored&nbsp; toga,&nbsp; u&nbsp; radu&nbsp; je&nbsp; utvrđeno&nbsp; da&nbsp; primena&nbsp; limunske kiseline&nbsp; utiče&nbsp; na&nbsp; usvajanje,&nbsp; akumulaciju&nbsp; i&nbsp; toleranciju vrba na prisustvo Cd,&nbsp; te&nbsp; rezultati ove&nbsp; studije&nbsp; imaju&nbsp; praktičan&nbsp; značaj&nbsp; u&nbsp; usavr&scaron;avanju&nbsp; tehnika&nbsp; fitoremedijacije&nbsp; i dekontaminacije zagađenih područja.</p>

<p>The role of citric acid on morphological, physiological and biochemical characteristics of selected willow clones (Salix spp.) grown in soil with moderately polluted cadmium (Cd)&nbsp; was&nbsp; presented.&nbsp; The&nbsp; aim&nbsp; of&nbsp; this&nbsp; study&nbsp; was&nbsp; to&nbsp; determine&nbsp; the&nbsp; Cd&nbsp; accumulation, translocation&nbsp; and tolerance of different willow clones, as well as the influence of citric acid as a chelator in the assisted phytoremediation process.&nbsp; In order to achieve this goal, plants&nbsp; were&nbsp; grown&nbsp; in&nbsp; semi-controlled&nbsp; conditions&nbsp; for&nbsp; 3&nbsp; months.&nbsp; The&nbsp; experiment&nbsp; was divided&nbsp; into&nbsp; two&nbsp; phases&nbsp; (two&nbsp; years&nbsp; of&nbsp; research),&nbsp; based&nbsp; on&nbsp; differences&nbsp; in&nbsp; the methodological approach, regarding the application of citric acid. During the first-year experiment, citric acid was added once, while in the second year the application of this chelator was performed in three repetitions.&nbsp; The analyses included:&nbsp; the accumulation and distribution of Cd in soil and various plant organs (root, stem, young and old leaves); influence of Cd and citric&nbsp; acid on morphometric parameters: stem hight and diameter, number&nbsp; of&nbsp; leaves,&nbsp; biomass&nbsp; and&nbsp; area&nbsp; of&nbsp; leaves,&nbsp; biomass&nbsp; and&nbsp; volume&nbsp; of&nbsp; the&nbsp; root;&nbsp; on&nbsp; photosynthetic&nbsp; characteristics:&nbsp; net&nbsp; photosynthetic&nbsp; and&nbsp; transpiration&nbsp; rate,&nbsp; water&nbsp; use efficiency, stomatal conductance, intercellular concentration of CO2, concentration of photosynthetic&nbsp; pigments;&nbsp; on&nbsp; mineral&nbsp; nutrition&nbsp; and&nbsp; distribution&nbsp; of&nbsp; macronutrients&nbsp; in plants (nitrogen, phosphorus and potassium content); on the content of the amino acid proline&nbsp; and&nbsp; cysteine;&nbsp; on&nbsp; the&nbsp; activity&nbsp; of&nbsp; antioxidant&nbsp; enzymes&nbsp; (catalase,&nbsp; ascorbate peroxidase,&nbsp; guaiacol&nbsp; peroxidase),&nbsp; as&nbsp; non- enzymatic&nbsp; components&nbsp; such&nbsp; as&nbsp; reduced glutathione and thiol content.<br />The obtained results indicated the genotypic specificity of the analyzed willow clones in the phytoremediation process, depending on the treatment applied, the Cd dose, and the presence of&nbsp; citric acid.&nbsp; The toxic effect was not evident on the morphological&nbsp; level, while&nbsp; the&nbsp; applied&nbsp; treatments&nbsp; showed&nbsp; a&nbsp; significant&nbsp; influence&nbsp; on&nbsp; the&nbsp; physiologicalbiochemical processes in the willows. The net photosynthetic rate, transpiration rate, as well as,&nbsp; water use eficiency&nbsp; showed decreasing with increasing Cd concentration in plant tissue,&nbsp; while&nbsp; the&nbsp; application&nbsp; of&nbsp; citric&nbsp; acid&nbsp; mitigated&nbsp; the&nbsp; harmful&nbsp; effect&nbsp; of&nbsp; this&nbsp; heavy metal, which was registered on combined treatments. In response to the accumulation of Cd in plant tissue, a&nbsp; change in the&nbsp; activity&nbsp; of&nbsp; anti-oxidant enzymes,&nbsp; as&nbsp; well as nonenzymatic&nbsp; components&nbsp; of&nbsp; the&nbsp; defense&nbsp; system&nbsp; has&nbsp; been&nbsp; established.&nbsp; In&nbsp; addition,&nbsp; the<br />application of citric acid showed the promotion role on the&nbsp; absorption, accumulation and tolerance of willows grown in moderately polluted soil cadmium, which has a practical significance in the improvement of phytoremediation techniques and decontamination of polluted soil.</p>