Effects of Endophytic Actinomycetes Extracts on Seedling Growth of Tested Plants

Endophytic actinomycetes are utilized as potential sources of novel natural products for exploitation in weed management. The present study aimed to investigate the allelopathic effects of endophytic actinomycetes extracts on germination and growth of test plants. Leaf and roots sample of tangerine tree in Fang District, Chiang Mai Province were randomly collected and isolated into seven isolates for the experiment. It was found that endophytic actinomycetes crude extract from isolate TGsR-01-004, TGsR-01-005, TGsR-02-017, TGsR-02-018, TGsL-02-004, TGsL-04-028, and TGcL-04-053 reduced the germination rate, shoot length and root length, as well as the fresh weight and dry weight of Lactuca sativa seedlings compared to the control group in a statistically significant manner. In addition, the TGsL-04-028 extracts of supernatant part with increasing concentration exhibited a more pronounced inhibitory effect on L. sativa germination and growth than cell extracts from the same isolate. However, the extracts from endophytic actinomycetes had significantly inhibited germination and growth of L. sativa and Bidens pilosa depending on isolate and test plant species. Our results suggest that endophytic actinomycete had an allelopathic effects on plants growth and suggest a promising avenue for investigating allelochemicals that could potentially serve as effective alternatives for the development of novel bioherbicides. Thus, endophytic actinomycetes hold considerable promise as a source of novel natural products for weed management strategies.