Seed Viability of Heracleum mantegazzianum (Apiaceae) Is Quickly Reduced at Temperatures Prevailing in Biogas Plants

Tanke Tanke,De Mol De Mol,Müller Müller

doi:10.3390/agronomy9060332

Abstract

Heracleum mantegazzianum is an invasive plant species with enormous effect on ecosystems and human health. Mechanical weed management often results in large amounts of biomass. Fermentation in biogas plants can be used for disposal of this biomass contaminated with seeds and for energetic utilization, if spreading of viable seeds with fermentation residues is prevented. Our aim is to quantify the risk of seed survival in mesophilic biogas plants. Seeds were harvested at three ripening stages in central Germany. They were incubated for 0, 0.5, 1, 2, 4, and 8 days at 35 and 42 °C in water baths. Thereafter, seed viability was assessed by a tetrazolium test. Furthermore, germinative capacity of seeds which had passed an incubation of 48 h at 35 °C were tested. After eight days in water bath none of the 1199 tested seeds were viable anymore. The time until half of the seeds died (ED50) ranged from 9 to 65 h, whereby high temperature accelerated the mortality. Germinative capacity was similar to the seed survival rate. The results suggest that fermentation of H. mantegazzianum biomass poses only a low risk of viable seed spread, if the operating temperature of the biogas plant achieves 42 °C and a high retention time is ensured.

Highlights

Heracleum mantegazzianum Sommier & Levier, giant hogweed, is one of the most successful invader weed species in Europe [1], causing biodiversity loss and reduced ecosystem functioning [2,3,4]
For the invasive species management, our results suggest that the disposal of H. mantegazzianum biomass contaminated with seeds in biogas plants poses only a low risk
The risk is a function of the number of viable seeds introduced in the biogas process

Summary

Introduction

Heracleum mantegazzianum Sommier & Levier, giant hogweed, is one of the most successful invader weed species in Europe [1], causing biodiversity loss and reduced ecosystem functioning [2,3,4]. Competitive growth and reproduction potential giant hogweed species have a high potential for further infestation and strong survival [5,6,7]. Preserving biodiversity is part of the Convention on Biodiversity, with regard to taking precautions against alien species and, if necessary, controlling them [8]. In the vicinity of human settlements, control of H. mantegazzianum is necessary due to health hazards, because it contains photosensitive furanocoumarins that can cause skin burns and blindness [9]. Contamination of the biomass with germinable seeds poses a risk of dispersal during disposal and promotes further infestation

Objectives

Results

Conclusion