ALLELOPATHIC EFFECT OF TWO WEED SPECIES, ABUTILON THEOPHRASTI MED. AND DATURA STRAMONIUM L. ON GERMINATION AND EARLY GROWTH OF CORN

U cilju smanjenja primjene kemijskih sredstava za zaštitu bilja novija istraživanja znanstvenika, sve više su usmjerena na različite alternativne „nekemijske“ mjere borbe protiv štetočinja. Od njih se traži da budu približno učinkovite kao kemijske mjere, a da manje štete okolišu. Alelokemijske sposobnosti biljaka uočene su već u 3. st. prije Krista ali su se tek u 20. st. počele intenzivno proučavati. Cilj ovog rada bio je proučiti alelokemijske sposobnosti dviju korovnih pridošlica u Republiku Hrvatsku, mračnjaka - Abutilon theophrasti Med. (ABUTH) i kužnjaka - Datura stramonium L. (DATST). U tu svrhu postavljena su dva pokusa kojima se ispitivao alelopatski utjecaj biljne mase ekstrakta nadzemnog i podzemnog dijela mračnjaka kao i vodenog ekstrakta nadzemnih dijelova kužnjaka na početni rast i razvoj kukuruza (Zea mays L.). Ocjena alelopatskog utjecaja utvrđena je mjerenjem ukupnog postotka klijavosti, duljine korijenka i klice kukuruza. Istraživanjima je dokazan izrazit inhibirajući učinak korovne vrste Abutilon theophrasti Med. na duljinu korijenka, klice kao i na ukupnu klijavost zrna kukuruza. Korovna vrsta Datura stramonium L. imala je suprotan, odnosno stimulirajući učinak na duljinu korijenka kukuruza. Primjenom ekstrakta iz nadzemnih dijelova obje istraživane korovne vrste smanjena je ukupna klijavost zrna kukuruza mjerena tri, šest i 10 dana nakon tretiranja. Provedenim pokusima dokazane su, inhibirajuće i stimulirajuće alelopatske interakcije između dviju istraživanih korovnih vrsta i kukuruza.In view of minimising the use of pesticides in agriculture, scientific researchers all over the world are oriented to ther “alternative”, “non-chemical” weed control measures which are required to be efficient as chemicals but should be beneficial to the environment. Although allelopathy interactions between plants were observed in the 3rd century BC, allelopathy and allelochemicals started to play an important role in agriculture in the 20th. The aim of this paper was to investigate the allelopathic effect of two important non-native weed species in Croatia, Abutilon theophrasti Med. (ABUTH) and Datura stramonium L. (DATST). Both of the weeds are very competitive in corn crops and cause great losses in corn yields. Laboratory experiments were conducted in 2004. and 2005. In the first experiment allelopathic effect of aqueous extract of fresh shoot and leaves, and separately aqueous extract of roots of Abutilon theophrast Med. on germination and early growth of corn (Zea mays L.) were examined. In the second experiment allelopathic effect of above part of plant of both weeds were examined only. Aqueous extracts of Abutilon theophrasti Med. inhibited strong germination, radicle and coleoptile length of corn. On the other side promoting effect on radicle length was noticed by aqueous extract of Datura stramonium L. Germination of corn, measured 3, 6 and 10 days after treatments, was inhibited by aqueous extracts of above ground part of plants of both weed species