Diversity of weed flora, selected biometric characteristics and yielding of Miscanthus spp. cultivated on light and heavy soil

An important issue related to the cultivation of plants for energy purposes and poorly recognized so far is their impact on the environment, including biodiversity. The aim of the work was to assess weed flora diversity, canopy structure and yield of miscanthus cultivated on two types of soil: light and heavy. The study was carried out in the Experimental Station of the Institute of Soil Science and Plant Cultivation – State Research Institute at Osiny, Poland (N:51o28, E:22o4), on two fields of miscanthus (Miscanthus saccharflorus Robustus × M. sinensis– M-115) established in 2004, on light loamy sand and heavy loam. The analysis of weed flora was carried out in 2010 and 2011, in mid-June and mid-August, using two methods: the frame method and phytosociological relevés. Moreover, an analysis of green and dry matter yield of miscanthus, some biometric features and leaf area index (LAI) was carried out. The results showed that weed species diversity in a miscanthus crop was dependent on soil type. A larger number of weed species was found in miscanthus cultivated on heavy soil – 37 – in comparison with miscanthus cultivated on light soil – 33. Sorensen’s indicators showed low similarity between weed communities in miscanthus on light and heavy soil. Weed abundance and percentage of weed cover were lower in miscanthus cultivated on light soil. Weed density decreased during the vegetation season as a result of increasing competitiveness of the miscanthus canopy against weeds. Miscanthus yields were more dependent on weather conditions than the type of soil. Plant height and shoot diameter as well as leaf area index (LAI) were higher in miscanthus grown on heavy soil