DBG · Promoting young researchers

Jan Hendrik Hoerner (Bielefeld University)

Jan Hendrik Hoerner's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Bielefeld University in the year 2017.

Title of awarded thesis

"Allelopathic effects of the invasive plant Erodium cicutarium on agricultural crop plants"

The invasive common stork´s-bill Erodium cicutarium causes yield reduction of various crops in North America. Jan Hendrik Hoerner examined responsible allelochemicals, natural substances produced by the stork´s-bill, which are able to suppress the growth of other plants. He fractionated phenolic compounds with high inhibitory effects, even in minor concentrations.

The common stork´s-bill Erodium cicutarium (Geraniaceae) is an annual herb with global distribution and high competitive ability, allowing it to become a dominant invasive plant in North America. E. cicutarium causes high yield losses in several crops: up to -92 % in peas, -82 % in dry beans, -37 % in canola and -36 % in wheat. Further ecological detrimental effects of invading E. cicutarium have been described. Until now, the underlying chemo-ecological mechanism for the success is largely unknown.

The objective of the present study was to evaluate possible allelopathic effects. Therefore, the impact of E. cicutarium rhizosphere soil from the climate chamber and field grown plants, as well as leaf extracts from plants of different life stages and subjected to simulated mowing on crop plant seedlings were examined. The samples with the highest allelopathic activity (methanolic leaf extracts of twelve-weeks-old climate chamber grown plants subjected to simulated mowing) were more thoroughly investigated by a solid phase extraction and high-performance liquid chromatography. Subsequently, bioassays with separated fractions and pure natural chemicals which had been identified confirmed the allelopathic potential of some phenolic compounds. Ellagic acid, for example, causes a significant growth inhibition at 15.6 µg / mL and gallic acid at 31.3 µg / mL.

Interestingly, raw extracts provoked the highest relative growth inhibition. Probably different allelochemicals work synergistically. Potentially the use of raw extracts for analyzing the effects of allelochemicals could better simulate ecological reality than (isolated) pure compounds. The investigation of allelopathy is relevant for agriculture, crop rotation and nature conservation.


Jan Hendrik Hoerner conducted this work at the Department of Chemical Ecology in the working group of Prof. Dr. Caroline Müller.

A) The plant Erodium cicutarium (L.) L’Hér. ex Aiton. B) The lobed cotyledons are an important feature to distinguish E. cicutarium from seedlings from other species of its genus. C) The sharply pointed and hairy base of E. cicutarium seed facilitates zoochory. D) Upcoiling awn of the ripe and dry E. cicutarium seed. Once on soil, humidity causes the helical shape to unwind and drill the seed with the sharply pointed base ahead into the ground. Graphs: Jan Hendrik Hoerner
A) Boxplots of L. sativum seedling radicle grown on leaf extracts of twelve-weeks-old E. cicutarium plants with simulated mowing (leaf extract 12 W CL) and without mowing (leaf extract 12 W) were compared to methanol (solvent control): L. sativum, radicle length: Kruskal-Wallis H-test (chi-square= 24.815, df= 2, p= 4.09E-06), Mann-Whitney U-test post hoc analysis:12 W CL leaf extract vs. solvent control: (U= 100, Z= 3.742, p= 1.83E-04), 12 W leaf extract vs. solvent control: (U= 100, Z= 3.742, p= 1.83E-04), 12 W leaf extract vs. 12 W CL leaf extract: (U= 4, Z= -3.439, p= 5.83E-04). Different letters in the graph indicate statistical differences between the samples. Significance-levels: p > 0.05= ns, p < 0.05= *, p < 0.01= **, p < 0.001= ***, n= 10 replicates. B) Photograph of the L. sativum seedlings grown for three days on the above mentioned E. cicutarium leaf extracts or on the evaporated solvent control. Displayed are the seedlings of the first four – five replicates. Plant age and simulated mowing increases allelopathic potential. Graphs: Jan Hendrik Hoerner