Agnieszka Synowiec

Do the seeds of Solidago gigantea Aiton have physiological determinants of invasiveness

Solidago gigantea Ait. (goldenrod) belongs to the most expansive environmental weeds, and it is the most dangerous plant-invader of American origin in Europe. The species easily propagates vegetatively, but it also produces large amounts of wind-disseminated achenes that contribute to the colonization of new areas. A sound knowledge of the germination biology of goldenrods is required to control the spread of this invasive species. The objective of this study was to investigate selected aspects of germination of giant goldenrod achenes and to determine: the influence of temperature and humidity on seed dormancy and germination, the content of soluble carbohydrates in seeds and the sensitivity of seeds to selected phytohormones. Unlike native weed species of the same family, S. gigantea seeds did not display symptoms of innate dormancy, and high seed vigor was maintained after storage in a wide range of temperatures, in both dry and moist conditions. The physiological mechanisms behind those traits have not yet been fully explored, but they could be associated with the relatively high sucrose-to-hexose ratio in seeds and significant sensitivity to abscisic acid. More extensive research is required to explain the internal causes for the atypical behavior of goldenrod seeds during dry and moist storage, especially in the context of its invasiveness, because the species has a preference for sites located close to river banks.

Effect of Fatty Acid Methyl Esters on the Herbicidal Effect of Essential Oils on Corn and Weeds

In this study, we tested whether the addition of fatty acid methyl esters (FAME) of edible oils would influence the herbicidal effect of the essential oils (EO) of fiber hemp and peppermint (Mentha × piperita L.) against common lambsquarters, barnyardgrass, and corn. The herbicidal properties of a 2.5% concentration of each EO in water mixtures with FAME were evaluated as sprays in a pot experiment. The oil-FAME mixtures showed phytotoxic effects against common lambsquarters and barnyardgrass expressed by a reduction in plant length and aboveground and root biomass, as measured three weeks after foliar spraying. Corn was the most tolerant species to the tested mixtures. Sunflower FAME alone was safe on corn but reduced the growth of weeds. Peppermint EO alone was the most phytotoxic on all tested species. In conclusion, the mixture of peppermint EO with oilseed rape FAME was the best treatment; however, improvement on Ch. album would be desirable for commercial-level control. Nomenclature: Barnyardgrass, Echinochloa crus-galli (L.) Beauv. ECHCG; common lambsquarters, Chenopodium album L. CHEAL; common sunflower, Helianthus annuus L.; corn, Zea mays L.; hemp, Cannabis sativa L.; peppermint, Mentha × piperita L. Huds. var. officinalis Sole, f. rubescens Camus; rape, Brassica napus L.; soybean, Glycine max (L.) Merr.

Accumulation of biomass and bioenergy in culms of cereals as a factor of straw cutting height

Abstract Cereal straw is an important biomass source in Europe. This work assessed: 1) the morphological and energetic characteristics of culms of spring and winter cereals, 2) the energy deposited in the different aboveground parts of cereals, 3) losses of energy due to different cutting heights. The straw of winter and spring cereals was collected from arable fields during the seasons 2009/10 and 2010/11 in southern Poland. Detailed biometric measurements of culms and internodes were performed. The losses of straw biomass and energy were assessed during simulation of cutting the culm at different heights, up to 50 cm. Longer and heavier culms were developed by winter wheat and triticale and oat. Cutting of straw up to 10 cm did not lead to significant losses in straw yield. The total amount of energy in the culms was as follows: triticale > winter wheat > oat > spring wheat > winter barley > spring barley. Cutting the culms above 20 cm led to significant differences in terms of biomass energy between cereal species. The smallest losses of energy were recorded for spring and winter barley. Oat and barley accumulated the highest energy in grains.

Composition and herbicidal effect of Heracleumsosnowskyi essential oil

Abstract Plants of Heracleum sosnowskyi Manden. are rich in essential oil which might be of herbicidal potential. In this study, we examined 1) the content and chemical composition of H. sosnowskyi essential oil (EO) distilled from seeds and 2) the herbicidal effect of EO in a bioassay against germination of maize and five weed species. As a result, a 5.1% EO yield was obtained from the seeds of H. sosnowskyi. We identified sixty-two compounds of EO that constituted 96% of the total oil. Aliphatic esters were the main constituents of the EO, followed by aliphatic alcohols. The tested seeds showed different susceptibilities to the tested concentrations of EO (0.2 – 7.2 g L-1). The most susceptible were Bromus secalinus and Avena fatua, and the most resistant were Echinochloa crus-galli and maize. Kernels of maize germinated normally up to a 0.6 g L-1 dose of EO, and 20% of the seedlings were still germinating in the presence of 7.2 g L-1 of EO. These findings suggest that the EO of H. sosnowskyi and its main compounds should be studied further in soil conditions for its herbicidal properties against A. fatua and weeds in maize.