Common ragweed is a species with a negative impact on: agriculture, biodiversity and human health. This plant produces a large amount of strong allergen pollen, producing allergic rhinitis and severe asthma, affecting more than 20% of the population of infested areas. In recent years, Ambrosia artemisiifolia in Romania shows the trend of invasion of agricultural crops, where it can cause high damages by decreasing the quantity and quality of yield and harvesting efficiency. Ambrosia artemisiifolia threatens the biodiversity of ecosystems by releasing into the environment some compounds of the allelopathic nature, thus eliminating other species. The research carried out by Beres revealed that this species contains phenolic and terpene compounds. The allelopathic influences of A. artemisiifolia were tested in soybean, rice and maize bioassays. The purpose of this study was to highlight the allelophatic effect of the species Ambrosia artemisiifolia on crop plants (maize) and on spontaneous plants (redroot pigweed). Research was conducted under laboratory conditions. The experience included 3 variants in 3 replicates, both for maize and for redroot pigweed. 25 g of material mixed with 800 ml of distilled water was used to prepare the extracts, they were placed on the magnetic stirrer for six hours, after which filtration was carried out. The maize and redroot pigweed seeds were placed on a filter paper in a Petri dish (10 seeds / Petri dish). The extracts used in the study differed by the three concentrations: 30%; 60% and 90%. The maize seeds were treated with 6 ml of the respective extract, 12 ml for redroot pigweed seeds. It was observed that maize seeds showed germination rates ranging from 90% to 100%. The extracts from the leaves of Ambrosia artemisiifolia in the concentration of 60% and 90% reduced germination of maize seeds by 10% compared to the control. The corn root length was between 2.39 cm - 5.06 cm. The height of the maize plants, at 7 days after treatment, presented values of 1.17-3.30 cm. The studies carried out showed that the variants treated with leaf extract of Ambrosia artemisiifolia 30% determined the stimulation of the root length and the "height of the plant" character. The extracts of the leaves of the common ragweed have caused very significant decrease of Amaranthus retroflexus seeds germination (2.22% - 80%).

Ambrosia artemisiifolia, Amaranthus retroflexus, extract, concentration, allelopathic

biology

Presentation: poster