The structure and diversity of world crops’ weed flora are greatly influenced by the pronouncing global climate change, which are reshaping the face of the modern agricultural production. The phytocoenological surveys conducted during the summer period in the years 2004 and 2023 in the northeastern Croatia determined qualitative and quantitative changes in the row crops’ weed communities. Maize, soybean, sunflower, and sugar beet fields were visited each time in June when the weed vegetation was fully developed, and all occurring weed species within the randomly selected 10 m × 10 m quadrats per 30 and 29 fields in the 2004 and 2023, respectively, were evaluated using a seven-degree Braun-Blanquet scale. The weed community from past research was more heterogeneous, compared to a recent survey. In the past period (2004), weeds with the C3 photosynthetic pathway dominated in the community, while the C4 plants were significantly underrepresented. However, the dominance-diversity curve in the recent survey (2023) depicts a similar slope of the curve indicating the growing abundance and species richness of the C4 weeds. This shift in ranges of weed species with the C3 and C4 photosynthetic pathways confirms that climate conditions exert a significant influence on the spread, population dynamics, and infestation pressure.

weeds, row crops, climate change, C3 photosynthetic pathway, C4 photosynthetic pathway

agronomy

Presentation: poster