The effects of chitosan and its acetylation degree on in vitro seed germination and organ development in Ageratum houstonianum Mill.

The effects of chitosan oligomers (CHI) with acetylation degrees (DA) of 10% and 20% on the in vitro seed germination and organ development in Blue billygoat weed (Ageratum houstonianum Mill.) were investigated. The data were supported by photosynthetic pigment production, lignin content, and lipid peroxidation analyses. The chitosan treatments decreased seed germination rates and delayed germination. The CHI-20DA treatments were more effective than the CHI-10DA treatments in triggering shoot production. However, the CHI-10DA treatment at the highest concentration gave the longest shoots. The CHI-20DA treatment was better in triggering photosynthetic pigment production than the CHI-10DA treatment. Also, the CHI-20DA treatment at a high concentration induced higher lipid peroxidation than CHI-10DA treatments. However, the CHI-10DA treatment at high concentration enhanced lignin deposition, while the lowest level of CHI-20DA treatment gave the highest lignin content. The leaf production was not statistically affected by chitosan treatments at different DA but the highest concentration of CHI-20DA treatment decreased the mean leaf number. The highest level of CHI-20DA treatment significantly enhanced the plant’s rhizogenic response, whereas the same treatment dramatically reduced root elongation. The high concentrations of CHI-10DA or low concentrations of CHI-20DA treatments might be employed instead of synthetic growth regulators in A. houstonianum production to mitigate the detrimental effects of excessive chemical usage on nature. Considering the seed germination, low concentrations of 20% acetylated chitosan may be preferable over high concentrations of 10% acetylated chitosan. However, excessive use of higher-acetylated chitosan may impede shoot and root growth, which could result in nutritional deficiency.