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• Effect of Water and Nutrient Supply on the Allelopathy of Abutilon theophrasti Medic. and Xanthium italicum Mor

  102-105

  István Dávid

  Views:

  69

  Velvetleaf (Abutilon theophrasti Medic.) and Cocklebur species (Xanthium spp.) are more and more dangerous and „difficult to control” weeds in several cultivated plants. The ground cover of these species have became larger in Hungary like other warm-philous species. There are several causes of danger of them, for example: large capability for competition, allelopathic effect, keeping on of emergence.
  The allelopathic effect of these weeds were examined on sugarbeet (Beta vulgaris L.). Extracts of plants grown under different conditions have several effect on this species.
  Abutilon theophrasti plants were grown in perlite to examine the effect of supplying with nutritive materials on production of inhibitors. The water soluble exudates of the shoots grown with no artificial fertilisers inhibit stronger than grown with them. Acid soluble exudates have contrary effect. The exudates made of roots inhibited the sugarbeet less than shoots.
  Effect of drought stress on production of inhibitors was examined on Abutilon theophrasti and on Xanthium italicum. The species responded to missing of water different, and the water, acid and basic soluble exudates had different effect, as well.

• Allelopathic effect of invasive plants (Eriochloa villosa, Asclepias syriaca, Fallopia x bohemica, Solidago gigantea) on seed germination

  179-182

  Arnold Szilágyi

  László Radócz

  Tamás Tóth

  Views:

  257

  The aim of this study was to determine the allelopathic potential of invasive species woolly cupgrass (Eriochloa villosa), common milkweed (Asclepias syriaca), bohemian knotweed (Fallopia x bohemica), and giant goldenrod (Solidago gigantea Ait.) on germination crop (Lepidium sativum L.). Experiments were conducted under laboratory conditions to determine effect of water extracts in petri dish bioassay. Water extracts from fresh biomass (leaves and stem) of invasive weeds in concentrations of 4 and 8 g/100 ml were investigated. All invasive plants showed allelopathic effect on germination. In giant goldenrod stem water extract experiment, allelopathic effect was less pronounced.

  The cress germination was greatly suppressed with the woolly cupgrass, common milkweed and the giant goldenrod. The experiment showed that the seed germination depended on the concentrations and the plant material used (leaves and stem).

• Research on the allelopathic effect among the species Tanacetum vulgare and some agricultural crops

  105-109

  Nicolae Hodişan

  Nicolae Csep

  Views:

  116

  The research presents the results of the allelophatic effect upon the germination and growth of plants, immediately after springing, viewed as the interaction between the species of Tanacetum vulgare sin Chrysanthemum vulgare and three other crops: wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), rape (Brassica napus ssp. oleifera L.). The experiments that were performed consisted in applying treatments with aqueous extracts obtained from the roots, leaves, stems and flowers harvested from T. vulgare plants upon the seeds of the three agricultural crops mentioned before. In all aqueous extracts, the results indicate the presence of some chemical compounds that have inhibiting allelophatic effect. The plants upon which tests were made showed great sensitivity, the results on their germination and growth being significantly negative and highly significantly negative.
  The conclusions of this research sustain the idea of setting new research objectives in order to discover the chemical compounds from T. vulgare extracts that have such a stong effect and the possibilities they offer.

• Allelopathic Effect of Italian Cocklebur on Sugar Beet

  74-77

  István Dávid

  László Radócz

  Views:

  79

  Cockleburs are noxious weeds in Hungary, where they are widespread in row crops, especially in maize, sunflower and sugarbeet. A low density population of these weeds may be harmful because of their large competitive ability, fast growth in early phenological stages, allelopathy, and persistant sprouting.
  Allelopathy of Xanthium italicum Mor. was examined during the growing season in 2004. Root and shoot samples were collected at 4 or 5 leaves stage (in the end of May and in the beginning of June) and before flowering (in the beginning of July) before and after rain. Extracts were made in tap water. The test plant was Beta vulgaris L.; its germination, root and shoot growth were evaluated at the 6th and 10th days after treatment.
  Most of extracts inhibited the germination of sugar beet. In these experiments the phenological stage of the donor plant determined slightly the effectiveness of the extracts on sugar beet. Generally, significant differences existed between treatments only in cases of concentrated extracts.
  Rainfall can modify the inhibitory effect of extracts (especially shoot extracts). Shoot extracts of young plants inhibited stronger germination and growth after rain than before rain. Density of cockleburs influenced the effect of extracts, as well. Generally, differences between the efficacy of extracts was larger after rain.
  The results supported the hypothesis that the phenological stage and some environmental factors can modify allelopathy of cockleburs.