Allelopathic effects of Abutilon theophrasti, Asclepias syriaca and Panicum ruderale on maize
Abutilon theophrasti, Asclepias syriaca and Panicum ruderale are very important invasive weed species in Hungary. These can cause hard damages firstly in row space crops, because these have good competition ability. The aim our experiment was to study the allelopathic effect of watery extracts from roots and shoots on germination and growth of maize seedlings. Bioassay experiments were made in the laboratory in 2015. Extracts from air dried and grinded roots and shoots of weeds were made with water in 2.5, 5 and 7.5% concentrations. Maize (Cornelius) seeds were put into Petri-dishes, after that they were treated with 15 mL solutions, and put into a thermostat at 20 °C in the dark. After 7 days of germination, % and length and weight of primary roots and shoots of seedlings were determined. The statistical analysis has been done one-factorial analysis of variance. Shoot and root extracts of Abutilon theophrasti decreased germination-% and growth of primary roots and shoots of seedlings. Watery extracts from Asclepias syriaca resulted in similar effects; these treatments reduced germination and growth of seedlings. Shoot extract of Panicum ruderale caused shorter shoots and less shoot weight, and hindered the germination of maize. Root extract decreased shoot length and weight, and also germination, but root development was not influenced significantly. We established that allelopathic effects of A. theophrasti and A. syriaca were stronger than those of P. ruderale. Other publications reported significant results connected to allelopathy of A. theophrasti and A. syriaca. Mainly the root extracts inhibited the early growth of maize. Allelopathic effects were stronger with increasing concentrations of solutions.