Effect of Plant Age on Fresh Rhizome Yield and Volatile Oil Composition of Acorus calamus Linn.

Abstract

The effect of plant age on growth, yield and oil content and
composition of sweet flag (Acorus calamus) was studied in four
populations at four different ages, raised at CIMAP Experimental
Research Farm, India. The plant age had significant effect on total fresh
yield and leaves and rhizomes fresh weights. These parameters showed
increasing trend with advancement of harvesting age up to 6 years, and
age increase to more than 15 years resulted in their decrease. Significantly
highest number of shoots per square metre was recorded in more than 15-
year old crop, and the lowest number was recorded in the 6-year old crop.
The highest oil yield of rhizomes was obtained from the six-year old
plants. Shoot length, rhizome: leaf ratio (R/L) and oil yield of leaves did
not show significant differences with the age of the plant. However, 6-
year old plants recorded the highest average shoot length, and the three-
year old plants gave the highest oil yield of leaves. The total fresh yield
showed a highly significant positive correlation with rhizomes fresh
weight (r=0.999), leaves fresh weight (r= 0.994) and with rhizome: leaf
ratio (r= 0.998). Highly significant positive correlations (r=0.999) were
also obtained between rhizomes oil content and rhizomes oil yield and
between leaves oil content and leaves oil yield. β-asarone was the most
dominant constituent in the oils of both leaves and rhizomes, constituting
an average of 84.2% in the leaves and 88.9% in the rhizomes oil. The
study indicated that the oil content of fresh rhizomes and leaves is the
main contributor to their oil yields, and selection for high oil content will

be effective. The constituents of the volatile oil remained the same
irrespective of the plant age.