Alelopatski uticaj ekstrakata korovskih vrsta Abutilon theophrasti Med. i Xanthium strumarium L. na useve soje i kukuruza

Abstract

Kroz opšte, istorijske i okvire naučnih istraživanja, prvenstveno laboratorijskih ogleda, dat je presek nastanka, razvoja, današnjeg stanja i budućeg potencijala fenomena zvanog alelopatija. Potencijal alelohemikalija nameće potrebu analize biljaka jakog alelopatskog delovanja, identifikacije alelohemikalija, proučavanje njihovog mehanizma delovanja i njihove primene u biljnoj proizvodnji. Alelopatija se može odvojiti od ostalih mehanizama u okviru biljne zajednice jer je štetan efekat rezultat oslobađanja alelohemikalija i po tome se razlikuje od kompeticije. Alelopatija se smatra jednom od osnova održive poljoprivrede i zato je prioritetno područje istraživanja u razvijenim zemljama sveta. Cilj ovog istraživanja je bio da se utvrdi alelopatski uticaj ekstrakta korovskih vrsta Abutilon theophrasti Med. i Xanthium strumarium L. na inicijalni rast klijanca soje i kukuruza, kao i koncentracija ekstrakta ispitivanih korovskih vrsta koje imaju negativan uticaj na klijanje semena soje i kukuruza u laboratorijskim uslovima. U poljskim uslovima je cilj bio da se utvrdi koncentracija ispitivanih ekstrakata korovskih vrsta koja imaju negativan uticaj na prinos test biljaka, kao i da se odredi približna ocena broja individua po m2 sa potencijalnim negativnim uticajem na klijanje, nicanje i prinos useva soje i kukuruza. Ekstrakti korovske vrste A. theophrasti pripremljeni sa različitim rastvaračima su potvrdili značajno alelopatsko delovanje na procenat klijavosti soje i kukuruza. Etila-acetatni ekstrakt je izazvao najveći procenat klijavosti soje u najvećoj primenjenoj koncentraciji. Stimulativni efekat na dužinu podzemnog i nadzemnog dela klijanca soje su ispoljili tretmani sa vodenim i heksanolnim ekstraktom. Kod semena kukuruza, primena etil acetatnog ekstrakta A. theophrasti je dovela do najnižeg procenta klijavosti što ukazuje na inhibitoran alelopatski uticaj istog, zatim metanolni, dok su ostala tri ekstrakta (vodeni, heksanolni i butanolni) takođe potvrdili inhibitaran uticaj u sličnim procentima klijavosti. Dužina podzemnog i nadzemnog dela klijanca za sve primenjene ekstrakte je potvrdila alelopatsko delovanje ekstrakata. Najveći inhibitorni efekat je bio kod etil acetatnog ekstrakta na dužinu podzemnog i nadzemnog dela klijanca semena kukuruza. Primena ekstrakta korovske vrste X. strumarium je takođe potvrdila alelopatski uticaj na klijavost semena soje i kukuruza, kao i na dužinu nadzemnog i podzemnog dela klijanca. Izraziti inhibitorni efekat je konstatovan kod vodenog i metanolnog ekstrakta u sve četiri primenjene koncentracije ekstrakta. Kod heksanolnog ekstrakta u tri veće primenjene koncentracije (0,04-0,01g/ml) klijavost soje je bila ujednačena. Takođe, kod ovog ekstrakta je utvrđeno stimulativno delovanje na dužinu podzemnog dela klijanca soje, dok je na dužina nadzemnog dela pokazala izrazit inhibitorni efekat primenjenih koncentracija. Etil acetatni ekstrakt korovske vrste X. strumarium izazvao je klijavost soje od 100% u koncentraciji od 0,04 i 0,02 g/ml, dok je uz primenu dve niže koncentracije utvrđen manji procenat klijavosti. Međutim, dužina podzemnog dela klijanca je uz primenu koncentracije od 0,04 g/ml pokazala izrazit inhibitorni efekat, a primenom nižih koncentracija utvrđen je stimulativni efekat na dužinu podzemnog dela klijanca. Primena etil acetatnog ekstrakta je pokazala izrazit inhibitorni efekat u sve četiri primenjene koncentracije na dužinu nadzemnog dela klijanca soje. Ekstrakti korovske vrste X. strumarium su potvrdili alelopatsko delovanje na seme kukuruza u laboratorijskim uslovima. Najmanji procenat klijavosti su dala semena tretirana metanolnim ekstraktom, dok su najveću procentualnu klijavost imala semena tretirana heksanolnim ekstraktima. Priemena metanolnog i heksanolnog ekstrakta su pokazala inhibitoran efekat u svim primenjim koncentracijama na dužinu podzemnog i nadzemnog dela klijanca kukuruza. Kod primene najmanje koncentracije heksanolnog ekstrakta je utvrđen stimulativan efekat na dužina podzemnog dela klijanca kukuruza. Ogledi u poljskim uslovima su potvrdili rezultate dobijene u laboratorijskim uslovima. Usev soje tretiran vodenim ekstraktima korovske vrste A. theophrasti je umanjio prinos od 37,96-63,50%, dok je prinos kukuruza umanjen za 13,68-39,47%. Metanolni ekstrakt je takođe imao značajan alelopatski uticaj i smanjio je prinos za 21,05-37,37% kod useva kukuruza dok je kod soje procenat smanjenja prinosa bio za 42,34-60,58%. Prinos useva soje tretiran vodenim ekstraktima korovske vrste X. strumarium je smanjen za 40,88-45,26%, a prinos useva kukuruza je smanjen za 10,53-30,26% srazmerno primenjenim koncentracijama ekstrakta. Metanolni ekstrakt je smanjio visinu prinosa biljke za 20,26-36,32% kod useva kukuruza dok je kod useva soje procenat smanjenja prinosa bio za 48,91-56,20%.

Aphenomenon called allelopathy has been examined and explained through general, historical and scientific frameworks of scientific researches, first of all laboratory experiments, providing data on its cross-section of origin, development, current condition and future potential. It is possible to distinguish allelopathy from other mechanisms of plant community since its harmful effect appears as a result of the release of allelochemicals. For this reason it is also different from its competition. Allelopathy is considered to be one of the bases of sustainable agriculture, thus becoming a priority field of study in developed countries. The aim of this research was to determine the allelopathic influence of the extract of weed species A. theophrasti and X.strumarium on the initial growth of soybean and maize germs, as well as to determine the concentration of extracts of the examined weed species that have a negative impact on the germination of soybean and maize in laboratory conditions. Within field conditions, the aim of the research was to determine the concentration of the examined extracts of weed species that have a negative impact on the yield of test plants, as well as to determine the number of the examined weed plants per m2 that have a negative impact on germination, emergence and yield of soybean and maize. The extracts of weed species A. theophrasti prepared with different solutions confirmed the existence of significant allelopathic influence on the percentage of germination of soybean and maize. Ethyl-acetate extract applied in the highest possible concentration caused the highest percentage of soybean germination. Treatments with water and hexanol extracts had a stimulating effect on the length of the underground and over-ground part of soybean germs. Ethyl-acetate extract of weed species A. theophrasti caused the lowest percentage of germination of maize. In other words, it confirmed the strong allelopathic influence of the extract. Methanol extract was next on the list, while the last three extracts (water, hexanol and butanol) also confirmed the similar percentage of germination under allelopathic influence. The length of the underground and over-ground part of germs for all the applied extracts confirmed their allelopathic influence. Ethyl-acetate extract had the highest inhibitory effect on the length of the underground and over-ground part of maize. The application of the extracts of weed species X. strumarium also confirmed the allelopathic influence on the germination of soybean and maize as well as on the underground and over-ground part of the seed germs. Water and methanol extracts had a highly inhibitory effect in all four applied concentrations. Hexan extract in three applied concentrations of larger amount (0,04-0,01 g/ml) caused equal germination of soybean. Also, it is determined that this extract has stimulating influence on the length of the underground part of soybean, while the same concentration had the significant inhibitory effect on the length of the over-ground part. Ethyl-acetate extract of weed species X. stumarium in concentration of 0,04 and 0,02 g/ml caused 100% of soybean germination, while two concentrations with the lower amount of extract caused a smaller percentage of germination. However, concentration of 0,04 g/ml had a strong inhibitory effect on the length of the underground part of germs, while smaller concentrations had a stimulating effect on the length of the underground part of germs. The length of the over-ground part of germs showed a strong inhibitory effect of all four applied concentrations. The extracts of weed species X. strumarium confirmed the allelopathic influence on maize in laboratory conditions. The seeds treated by methanol extract resulted in the lowest percentage of germination, while the seeds treated by hexanol extracts had the highest percentage of germination. The length of the underground and over-ground part of the germ of maize also confirmed the significant inhibitory influence. Application of the smallest concentration of hexanol extract had a stimulating effect on the length of the underground part of germs, confirmed by high germination of seeds treated by that concentration. Experiments done in field conditions confirmed the results obtained in laboratory conditions. Soybean treated by water extract of weed species A. theophrasti resulted in reduced yield in the amounts of 37,96-63,50%, while maize yield was reduced in the amount of 13,68-39,47%. Methanol extract also had a significant allelopathic influence, reducing yield from 21,05-37,37% in corn crops, while in soybean crops the percentage of reduced yield was from 42,34-60,58%. Yield of soybean treated by water extracts of weed species X. strumarium was reduced in the amounts of 40,88-45,26%, while yield of maize went down in the amount of 10,53-30,26% pro rata to applied concentrations of extracts. Methanol extract reduced the amount of plant yield from 20,26-36,32% in maize, while the percentage