Book of Abstracts
11th IFOAM
Scientific Conference
11-15 August 1996
Copenhagen, Denmark
Abstract front
page
Subject index
Athor index
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Extra Papers
Non-chemical Control of Purple Nutsedge E16
Marambe, B. & Sangakkara, U. R.
Department of Crop Science, Faculty of Agriculture University of Peradeniya, Sri Lanka. |
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| Purple nutsedge (Cyperus rotundus L.), which is
considered the most troublesome weed in the tropics, is continuing to increase it's
severity under modern cropping systems. Although chemical techniques have been adopted in
the recent past to control this weed, several non-chemical techniques were also reported
to be partly successful. The enormous power to regenerate, and the difficulties faced by
farmers to kill the large number of tubers have rendered the control of this weed more
difficult. The present study was conducted to develop an effective non-chemical method to
suppress the growth and development of purple nutsedge. Thus, the effects of partial and
complete defoliation treatments imposed at 2 and 4 weeks after emergence (WAE) on weed
growth were investigated in field and pot experiments. Repeated-complete defoliation
reduced the regrowth ability of the nutsedge tubers when compared to single defoliations
and the non-treated control. This treatment reduced the leaf area and leaf dry weight of
the weed by 56% and 69% respectively when compared to the control treatment at 8 WAE. The
number of new tubers produced was un affected by the defoliation treatments. However, new
tubers showed significantly low dry weights when compared to that of the control
treatment. Repeated-complete defoliation also reduced the endoamylase (EC 3.2.1.1)
activity and the starch content in the mother tubers by 72% and 56%, respectively, at 8
WAE. However, the exoamylase (EC 3.2.1.2) activity of the tubers was unaffected by the
defoliation treatments. Single defoliation resulted in poor growth of nutsedge plants
during the early stages. However, at 8 WAE, the growth of these plants was similar to that
observed in the control plots. The results indicated that complete defoliation at 2 and 4
weeks after emergence would effectively suppress the growth and development of purple
nutsedge. This would increase the competitive performance of the crops grown in
association with this weed. Reduction of the endoamylase activity could be a major causal
factor attributable to the poor performance of purple nutsedge after defoliation. Marambe,
B.; Sangakkara, U. R. & Ratnayake, S. K. (1995): Control of tuber growth of purple
nutsedge (Cyperus rotundus L): Effects of drying and depth of burying. Proc. 15th
Asian-Pacific Weed Sci. Soc. Vol I (B), p. 562-566. |