Growth, stomata and trichome characteristics of diploid and tetraploid Artemisia annua L. plants

Tetraploid A. annua have been reported to have higher artemisinin level compared to diploid plants. This research aimed to evaluate growth, stomata, and trichome characteristics of diploids compared to tetraploid plants. Two accessions of diploids (K.I.B and K1.2.2) and two accessions of tetraploid plants (K2.2.9 and K3.2.1) V0M1 were grown in the field for 11 weeks. Growth of plants was investigated every week by measuring plant height, number of branches per plant, fresh and dry weights. Density and size of stomata were observed using light microscopy; the number of trichomes was observed by scanning electron microscopy. The artemisinin level was analyzed by HPLC. The results showed that the plant height of both diploid and tetraploid plants was comparable. From week-1 to week-11, all plants still increased in their plant height. Similarly, numbers of branches also increased except for diploid K.I.B plants. The highest growth rate of numbers of branches was found in tetraploid clone K3.2.1. However, the highest biomass production was found in diploid clone K1.2.2. The artemisinin level of tetraploid plants was higher than that of diploid plants. The level of ploidy was confirmed by flow cytometry analysis.