Plant-Growth Inhibitors in Purple Nutsedge (Cyperus rotundus L.)

Abstract

1) Methanol extracts obtained from dry matter of purple nutsedge tuber were fractionated into six fractions as shown in Fig. 1., and they were essential oil (F.1), neutral fraction (F.2), phenolic fraction (F.3), acidic fraction (F.4), ethylacetate soluble fraction (F.5), and precipitates in methanol extracts (F.6).
2) Two fractions, F.1 and F.6, inhibited the germinations of lettuce (Lactuce sativa L. cv. New York) and white clover (Triforium repens L.) at the concentration of 400ppm, but the other fractions were less effective. Furthermore, F.1 and F.6 incorporated in pots appeared to be inhibitory on the growth of seedlings of lettuce, large crabgrass (Digitaria adscendens Henr.) and white clover. The seedlings treated also showed reductions in dry weight. These fractions also gave an inhibitory effect on the growth of the nutsedge plant itself.
3) The essential oil content in purple nutsedge was high in underground parts such as tubers, rhizomes and roots. However, the essential oil content changed both in aerial and underground parts throughout the growing season. Especially, a remarkable changes was shown in the roots from 30 days to 60 days after planting.
4) GC-MS analysis indicates the presence of sesquiterpenoids such as cyperene, β-elemene, caryophyllene, α-humulene, β-selinene, cyperenone and α-cyperone in the steam distillate of soil with purple nutsedge. These data suggested that components of F.1 and F.6 are responsible for inhibitory action on test plants.