Jiahao Xue

Lolium multiflorum is of worldwide agricultural importance as both a pasture crop and as a weed. We collected the seeds of 67 L. multiflorum populations from wheat lands in eastern China and three populations as commercial crop seeds; tested seed germination responses to temperature, osmotic potentials, and light/dark conditions; and also tested seed dormancy. Under constant temperatures, the germination percentages at 3 d after treatement (DAT) at 10, 15, 20, 25, 30, and 35 °C were 0%, 2.6 ± 0.5%, 37.1 ± 2.4%, 66.6 ± 1.9%, 68.2 ± 2.3%, and 37.3 ± 2.2%, respectively, and increased to 72.4 ± 2.0%, 95.6 ± 0.7%, 97.0 ± 0.7%, 98.3 ± 0.6%, 94.9 ± 1.0%, and 86.3 ± 1.2% at 14 DAT. The seed germination percentages in complete darkness at 14 DAT (averagely 87.4%) did not show significant differences with those in 12 h light/12 h dark treatment. The osmotic potential required for 50% germination (GO₅₀) was −0.53 to −0.13 MPa, with an average of −0.38 MPa, and the average germination percentage under −0.6 MPa at 14 DAT was 0.9%. The germination percentages of freshly mature seeds stored for 0, 15, 30, and 60 d were 61.3%, 66.5%, 68.4%, and 88.0%. L. multiflorum populations collected from wheat fields with rice as the preceding crop (paddy fields) showed significantly higher germination percentages under 10 °C, and lower germination percentages under osmotic stresses, compared with those collected from wheat fields with corn as the preceding crop (drylands). This is the first report of L. multiflorum seed germination biology based on multiple populations with different sources in China and provides insights for improving its management strategies.

Echinochloa crus-galli and E. crus-galli var. mitis are two of the most troublesome rice weeds. Florpyrauxifen-benzyl is one of the most important post-emergence rice herbicides that has been pervasively applied in many countries since 2018. We collected 70 E. crus-galli and 158 E. crus-galli var. mitis populations from rice fields in eastern China in 2022 and tested their sensitivities to florpyrauxifen-benzyl through whole-plant bioassays. A total of 21 days after treatment with florpyrauxifen-benzyl label dose (36 g ai ha⁻¹), 71.4% of E. crus-galli and 70.9% of E. crus-galli var. mitis populations were completely controlled. The GR₅₀ doses (doses causing 50% fresh weight reductions in aboveground parts) of florpyrauxifen-benzyl applied to E. crus-galli populations ranged from 1.4 to 36.9 g ai ha⁻¹, with a baseline sensitivity dose of 4.9 g ai ha⁻¹; those for E. crus-galli var. mitis populations ranged from 1.3 to 97.6 g ai ha⁻¹, with a baseline sensitivity dose of 5.0 g ai ha⁻¹. No significant differences between E. crus-galli and E. crus-galli var. mitis were found in GR₅₀ values. Among 70 E. crus-galli populations, 61.4%, 35.7%, and 2.9% showed no, low, and moderate resistance to florpyrauxifen-benzyl, while among 158 E. crus-galli var. mitis populations, 54.4%, 36.1%, 1.9%, and 1.9% showed no, low, moderate, and high resistance to florpyrauxifen-benzyl, respectively. Moreover, the frequency of florpyrauxifen-benzyl-resistant populations of E. crus-galli var. mitis tended to be higher in southwestern areas.

Weeds represent increasingly troublesome threats to modern wheat production. Jiangsu Province, China, is one of the largest wheat-planting areas, characterized by a high level of agricultural mechanization, in the country. In 2024, we surveyed weed communities of 924 wheat lands from 308 sites in Jiangsu and compared them with historical data surveyed in 1999–2000 in this province. A total of 156 weed species belonging to 103 genera and 39 families were recorded. Compositae and Poaceae showed the highest species richness, with 26 and 23 species, respectively. Poaceae weeds accounted for 54.3% of the overall weeds in dominance values. Beckmannia syzigachne showed the highest proportion of the overall weeds in dominance values (19.2%). Compared with the historical data, weed diversity increased by 33.3% in species, and by 62.5% in families; grassy weeds such as Beckmannia syzigachne, Alopecurus japonicus, and Alopecurus myosuroides became more dominant, while several low-growing grassy weeds became less dominant. The dominance of broadleaf weeds, such as Galium spp., Vicia spp., and Veronica spp., decreased greatly, and a clear trend of weed homogenization among different areas and types of wheat lands was observed. This is the first investigation of weed community succession against the background of agricultural modernization in China.

Native weeds have a long history of adaptation to local environments. Understanding the relationship between the occurrence of native weeds and their life history traits is crucial for effective weed management and risk assessment of plant invasions. In this study, we surveyed native weed species and their dominance across 666 field sites in agricultural areas of Yangzhou City, China, and each site was 13.3 hectares in area. A total of 287 native weed species were recorded, referring to 63 families, among which 45% were 50–100 cm in plant height and 47% were of an erect life type. In terms of the proportions out of the total native weed occurrence dominance, Poaceae, Compositae, and Fabaceae weeds accounted for 30%, 13%, and 11%; liana and perennials both occupied 32%; and aquatic, hygrophyte, sun plant, and shade plant all occupied < 10%. Additionally, the proportions increased with increasing seed production per plant and with increasing weediness reported worldwide. Native weed groups holding moderate vegetative reproduction abilities, moderate seed sizes, or herbicide resistance showed higher proportions. Moreover, most of the native weeds surveyed were not succulent or thorny plants and did not hold thorns, awns, obvious hairs, or mucilage on their fruits.