Allelopathic activity of two invasive Impatiens species in temperate climate of Lithuania

This study determined the total phenolics content in various plant parts of invasiveImpatiens species and evaluate their phytotoxicity on germination and seedling growth of wheat(Triticum aestium L.) ‘Hamlet’(monocot) and rapeseed (Brasica rapus L.) ‘Cult’(dicot). In 2016,the allelopathic activity of two invasive Impatiens species (Balsaminaceae) viz., balsam [I.parviflora (origin C. Asia)] and Himalayan balsam [I. glandulifera (origin Himalayas)] wasassessed on seed germination of wheat and rapeseed ex situ. In Impatiens extracts phenolicscontent ranged between 0.001 and 0.008 mg g-1and these significantly inhibited the seedgermination and seedling growth of both recipient species. However, germination inhibitiondiffered for each recipient specie. Both Impatiens spp. extracts drastically inhibited the rapeseedgermination (4.5-81%) than wheat germination (62-86.5%) possibly due to different seed coatanatomy and thus, its permeability. Therefore the most drastic inhibition (90% and 86.5%) wasrecorded in rapeseed germination (4.5% and 11.5%) in 0.2% flower and fruit+seed extract of I.parviflora and I. glandulifera, respectively. Consequently, recruitment and regeneration of nativespecies might be negatively affected by the invasive Impatiens species in invaded habitats.