Invasive plants have very important ecological and socioeconomic impacts. Producing and dispersing many viable seeds are key plant functional traits for invaders. Ungulate grazing plays an important role in the endozoochorous seed dispersal within grasslands and rangelands. Grazing can be applied as a practical and economical control method for plant invasions. We analyzed the effects of seed passage through the goat digestive system on the germination and viability for Sorghum halepense and Malva parviflora, common invasive species with contrasted propagules and seed traits. Both studied species produced seeds able to survive, in a small percentages (c. 0.80–1.70%), after being eaten by goats. Most of the seeds (c. 40–55%) of both species were retrieved between 24–48 h after ingestion. Goat passage provoked a decrease (> 60%) in the germination percentage and seed viability of S. halepense that was higher with longer gut retention times. In M. parviflora, the goat gut passage did not break its primary physical dormancy, since no retrieved seed germinated with similar viability as the uneaten seeds (c. 90%). In view of our results, goat grazing can be applied as a useful method to control S. halepense and M. parviflora invasions. Goats should be kept in corrals for at least 4 days after grazing to prevent transferring viable seeds to uninfected areas.

Anaerobic digestion (AD) involves the breakdown of a substrate by mixed microbial communities in the absence of free oxygen. This process has many benefits leading to the production of bioenergy (biogas) and fertilizers (bio-fertilizers). Unfortunately, the bio-fertilizer made using AD may be contaminated with weed seeds and may have the potential of infesting the fields to which it is applied. Thus, the goal of this study is to determine the effects of AD on seed germination and viability of two undesirable crop plants (Triticum aestivum and Sorghum bicolor) and four weed species of reclaimed agricultural land near Qena, Egypt (Schouwia purpurea, Polygonum equisetiforme, Amaranthus viridis, and Lotus arabicus). Vegetative biomass of T. aestivum was used as the substrate, and cattle rumen fluid was used as the inoculum. The seeds of the six plants were placed in culture bottles and subjected to AD at 37 ± 2 °C for up to 16 days. Time to first germination (the time required for the first seed to germinate) and the percentage of seeds that germinated varied among the six species. The percentage germination of all six species decreased with increasing duration of AD, with no seeds germinating at 12 or 16 days of incubation. Seeds of T. aestivum and S. bicolor experienced a rapid and significant decrease in the percentage of viable seeds and an increase in the percentage of non-viable seeds. In contrast, even though they did not germinate, some seeds of the other four weed species remained viable, even after 16 days of incubation. Approximately 32% of S. purpurea seeds remained viable at 16 days of incubation. Overall, our results suggested that the application of anaerobic digestate in the reclaimed agricultural lands near Qena, Egypt, is not likely to exacerbate weed infestations in these fields.

Sugarcane is a high-value crop in Egypt, yet weed communities in the understudied Upper Egypt region have not been systematically characterized. This study provides a comprehensive analysis of weed floristic composition, phytogeographical affinities, and the edaphic and canopy light factors governing vegetation structure across contrasting Nile Valley clay and reclaimed desert lands in Qena Governorate. Fourteen stands were surveyed during the 2024/2025 sugarcane growing season, recording 110 species from 33 families (68 annuals and 42 perennials), which were dominated by Poaceae, Asteraceae, Fabaceae, Euphorbiaceae, and Amaranthaceae (54.6% of the flora recorded). Therophytes were the most abundant life form (60.9%), and 51.8% of species belonged to Neotropical, Palaeotropical, Cosmopolitan, and Pantropical chorotypes. Diversity indices showed high and balanced species diversity, with no dominance by any single species. Seasonal variation showed that species richness peaked in spring, decreased through summer and autumn, and correlated with light intensity under the canopy. TWINSPAN identified four vegetation groups, which were merged into three primary vegetation groups (A, B, and C) via DCA and CCA ordinations and linked to microhabitats shaped by elevation and soil physicochemical properties. CCA revealed that Group C (stands in the Nile Riverbank lands) had the highest diversity, which was associated with organic matter, clay, and field capacity. In contrast, Group A (stands of reclaimed desert land) had low richness linked to high levels of Total Dissolved Solids (TDS), Electrical Conductivity (EC), Na, K, Mg, CaCO₃, and sandy soils. Group B (stands of Nile clay lands) was an intermediate transitional community between groups A and C. These findings establish edaphic factors as the primary determinant of weed community structure, with salinity as the critical constraint in reclaimed lands and seasonal light variation as a secondary diversity filter.