Competition is a fundamental ecological interaction among plants, arising when species utilise the same limited resources such as light, water, nutrients, and space. Resource limitations reduce the growth and survival of less competitive species, altering ecosystem structure. In agroecosystems, weed–crop competition is a major challenge, reducing yield and quality. Weeds often exhibit greater adaptability and resource efficiency, enabling them to outcompete crops. Competition intensity is influenced by population density, morphology, phenology and survival strategies. Understanding plant competitive interactions is crucial for ecologists and agronomists to develop sustainable weed management and resource optimization strategies. Climate change further alters competitive dynamics, favoring resilient and plastic species. Mechanisms like allelopathy, aboveground and belowground competition and adaptive growth responses shape community structure. Strategies to reduce weed pressure include breeding competitive crops and integrating cultural practices such as optimal sowing density, narrow row spacing, and cover cropping. Future research should address plant responses to multiple simultaneous stressors, the ecological role of allelochemicals under varying conditions, and the genetic mechanisms of competitive adaptability. A comprehensive understanding of these interactions is essential for designing resilient, high-performing agroecosystems in changing environmental conditions.

Crop rotation is known as an eco-friendlier approach, as provides diversification in crop management systems, modifies intensive pressure on the agricultural ecosystem, utilizes various soil horizons, and prevents the establishment of specific pests and weeds. We set out here a study on the farms that have been managed over 50 years of specific continuous crop management programs. The experimental treatments were in a different management system: monoculture of maize, winter wheat, and soybean, 2-year crop rotation (winter wheat–maize) with and without chemical fertilizer, and 3-year crop rotation (winter wheat–soybean–maize) with and without chemical fertilizer and manure. We took soil samples six times from 2014 to 2017 prior to sowing and after harvesting each year. Weed seeds were extracted from soils and identified and counted by species. We, upon the data of a long term experiment of crop rotation, could conclude that crop rotations with more crops in the sequence are significantly effective in maintaining weed populations, a low-input crop production could reach a constant low population below an important damaging density, and therefore will be a more sustainable crop production while chemical fertilizers would change the soil’s chemical and structure and imbalance the plant population diversity and manures with high weed seed infestations have the potential to totally eradicate crop rotation effects, Therefore, clean manures or compost are highly recommended.

The application of minimal doses of herbicides is very popular due to concerns about the negative impacts of herbicides on the environment and public health. Studies were conducted to estimate the possibility of using quick and non- destructive methods to investigate Chenopodium album L. and Abutilon theophrasti Medik. response to mesotrione. The studies were conducted in a controlled environment to determine the response of C. album and A. theophrasti to mesotrione using dose–response curves created based on plant dry weight, chlorophyll fluorescence parameters and chlorophyll content. The obtained effective dose values showed that the studied weeds were susceptible to reduced doses of mesotrione. ED₉₅ values estimated for both species for dry weight and chlorophyll fluorescence parameters were lower than the recommended dose rate (120 g a.i. ha⁻¹), with less than 85 g a.i. ha⁻¹ needed to achieve a reduction of 95%, compared with untreated plants, while ED₉₅ value (A. theophrasti: 182 g a.i. ha⁻¹ and C. album: 180 g a.i. ha⁻¹) for chlorophyll content for both species was above the recommended dose rates. Consequently, dry weight and the chlorophyll fluorescence parameters are suitable for estimating the plant response to mesotrione, while chlorophyll content is not.

Plastic traits are argued to favor the establishment of invasive alien plants and to evolve during the invasion process, so that invasions may be favored by both plasticity and evolutionary changes in plasticity. Despite this aspect being pivotal to understanding invasion processes, no information is available about the effect of residence time on the evolution of phenotypic plasticity of aliens to produce locally adapted phenotypes. Therefore, we aimed to evaluate changes in the morpho-functional traits of the invasive alien Ambrosia trifida L. over time. Specifically, we grew A. trifida plants under laboratory (at different temperatures: 10 °C, 20 °C and 25 °C) and field conditions by using seeds collected from 2011 to 2020 from an Eastern European population. Data about seedling emergence, vegetative (laboratory and field) and reproductive (field) traits were collected, e.g., maximum plant height (cm), total dry biomass (g), number of flowers (n) and number of new seeds (n). Analysis of variance (ANOVA), linear regressions and a plasticity index were applied to assess differences in plant performances when grown from seeds of different ages. An auto-regressive integrated moving average (ARIMA) model was applied to predict future trends of some key plant traits (maximum height, total dry biomass and number of new seeds). Overall, the time of seedling emergence was not statistically different among seeds of different age, and regression analyses exhibited a positive relationship between residence time (seed age) and vegetative and reproductive parameters of A. trifida. Only male flower production exhibited a negative trend over time. At all temperatures (especially at 25 °C), the vegetative parameters increased with the decrease in residence time. The plasticity index of the measured traits tended to decrease over time for most traits both in the field and in the laboratory trials. The ARIMA model predicted that plant traits will continue to increase in size over time by 2030, suggesting further plastic adaptation of A. trifida. The results highlighted that residence time influences the evolution of phenotypic plasticity of A. trifida, which has strengthened its adaptability to the new conditions over a decade, also demonstrating a great adaptive and invasion potential for the future.

Plantation cultivation of medicinal plants is expanding, and since weed control is the biggest challenge in this production, the aim of the study was to examine the possibility of their control by mulching. In addition, herbicide metamitron was included in the study, the use of which in such crops is acceptable in some countries. Angelica archangelica L. was chosen as the experimental crop as its essential oil from the root is one of the most appreciated on the market, due to which an increase in its production areas can be expected. The experiment was set up in five treatments (completely random block system with four replications), as follows: agrotextile waterproof foil, sawdust, herbicide metamitron, control without weeds (positive) and control with weeds (negative). The highest weediness was recorded in the negative control, and in the treatment with herbicide metamitron. Sawdust mulch resulted in a reduction in weediness, compared to the previous two treatments. Agrotextile foil and positive control were free of weeds. Thus, the best efficiency in weed control was achieved by applying agrotextile mulch foil, which completely prevented weed germination (efficiency 100%), a much weaker effect was achieved by using sawdust (efficiency 51.28%), while metamitron reduced fresh weed biomass by only 26.71%. The obtained results show that mulching as a physical method of weed control in angelica crop is more suitable, in comparison with the application of the herbicide metamitron, if the crop is dominated by grass species, which are not in the spectrum of action of this herbicide. The significance of these results is even greater knowing that in our country metamitron, as well as other herbicides, is not registered for use in medicinal crops.

Gene flow is a main concern associated with the use of herbicide resistant sunflower crops because it could transfer herbicide resistance traits to weedy sunflower. In order to estimate potential gene flow from imazamox and tribenuron-methyl resistant sunflower hybrids to weedy sunflower, field experiments and DNA analysis were conducted. The progeny of weedy sunflower which grown near imazamox (WS1) and tribenuron-methyl (WS2) resistant hybrid in previous experiments were used. In the field experiment, recommended rates of imazamox and tribenuron-methyl were applied to WS1 and WS2, respectively, and plants surviving were recorded. Herbicides effect on fresh weight of survived plants were also determined. The presence of mutations responsible for sunflower resistance to herbicides (imazamox and tribenuron-methyl) checked based on DNA analysis of selected survived plants. Percentage of survived plants in field experiment was recorded at maturity and depend on weedy sunflower accession (WS1or WS2) and distance of their mother plants from resistant sunflower hybrid in previous experiment and was higher for WS2 (50.25%) than for WS1 (24.50%). As DNA analysis were not confirmed the presence of the point mutations responsible for sunflower resistance to imazamox and tribenuron-methyl.