Common ragweed (Ambrosia artemisiifolia L.) is becoming a health and economic threat as it spreads across Europe and other regions. A greenhouse experiment was conducted in 2010 in Slovenia to determine effect of various nitrogen (10, 50, 100 kg N/ha), soil moisture level (low and high) and competition levels (no, medium, high competition) on ragweed growth parameters. Single-grown ragweed responded favourably to nitrogen and water increase, while ragweed growth parameters in competition stands increased only with high nitrogen and water addition. High competition reduced the total dry matter by up to 83%, but ragweed still succeed to increase its relative growth rate in the full flowering stage and allocated its dry matter in the reproductive parts, producing up to 70 seeds. Ragweed is a poor competitor in the high resource availabilities, but in the conditions of environmental stress (shortage of nutrients and water) and disturbance which decreases intensity of competition its performance under moderate competition is barely affected. Medium nitrogen addition which promotes competitors species, prevention of disturbance and establishment of plant communities with stress tolerant species are measures that could be taken to prevent further ragweed spread.
COBISS.SI-ID: 3849832
As common ragweed (Ambrosia artemisiifolia L.) spreads across Europe and other regions, it is becoming both a health and an economic threat. To better understand which environmental conditions facilitate the spread of the invasive species, in 2010, a greenhouse experiment was conducted determining the effects of various nitrogen levels (10, 50 and 100 kg N/ha), soil moisture level (low and high) and competition levels (no competition, medium competition and high competition) on the growth parameters of ragweed. Single-grown ragweed responded favorably to the medium nitrogen and water increase, whereas the ragweed growth parameters in competition stands increased only when high levels of nitrogen and water were added. High competition reduced the total dry matter of ragweed by up to 83%, but the ragweed continued to increase its relative growth rate during the full-flowering stage and allocate its dry matter to reproductive parts, producing up to 70 seeds per plant. Ragweed is a poor competitor when there is high resource availability; however, under disturbance and in the shortage of nutrients and water conditions, the intensity of competition decreases and the ragweed performance is minimally affected. The addition of medium levels of nitrogen to promote the growth of competitive species, prevention of disturbance and establishment of plant communities with stress-tolerant species are measures that should help to prevent the further spread of ragweed.
COBISS.SI-ID: 3833448
Dry matter partitioning and allocation is a major determinant of plant growth and their competitiveness. Common ragweed is a troublesome agronomic weed species and because of its rapid spreading and production of allergenic pollen, it is also a major health concern in Europe and other countries. A field experiment was conducted in 2009 to determine effect of various nitrogen (N) levels (0, 100 and 200 kg/ha) and density (1.3, 6.6 and 13.2 plants/m2) levels on the ragweed leaf, stem dry matter partitioning and dry matter allocation. With increasing density the stem partitioning coefficient (PCstem) also increased, whereas the leaf partitioning coefficient (PCleaf) decreased. Addition of N resulted in limited effect on leaf and stem partitioning. Root dry matter production decreased with increasing density and was not influenced by N addition. Under intraspecific competition ragweed displayed a stronger aboveground than belowground intensity of competition resulting in greater root:shoot ratio compared to low-density stands. N level influenced the vertical leaf, stem and total dry matter distribution with a greater allocation to the top stratus of the ragweed, thus increasing their competition for light. The ragweed biomass allocation to the roots in response to the N supply displayed a low plasticity in contrast to the shoots which displayed high plasticity. Our results suggest that under intraspecific conditions and with increasing N supply ragweed would be more competitive for aboveground resource acquisition.
COBISS.SI-ID: 3850088