Degrading phenolic compounds and exhausting food reserves stored in the tubers of Cyperus rotundus L. with hydrolytic enzyme

Cyperus rotundus is one of the world worst weeds causes hundred per cent yield loss at times. Killing the mother tubers with the foliar applied herbicide prevent the translocation of herbicides to the secondary and tertiary tubers. Further the tubers can survive during adverse weather condition due to the presence of phenolic compounds and the food reserve. Hence an experiment was carried out with hydrolytic enzyme to degrade the phenolic compounds (germination inhibitor), to stimulate the germination and exhaust the food reserve in the tubers of weeds to kill before emerging. In the first attempt four different concentration of alpha amylase (50, 100, 150 and 200 ppm) and three different durations (6, 12 and 24 hours) were evaluated. In the second attempt six different concentrations (250, 500, 750, 1000 and 1250 ppm) of alpha amylase were tested for 72 hours. The biochemical parameters namely starch (Anthrone method), amylose (Rapid method) and phenols (Spectrophotometric method) were recorded at hourly intervals and viability of the tubers was tested following tetrazolium test. In the present study, it is observed that treating the tubers of purple nut sedge with alpha-amylase at 200 ppm recorded the minimum content of starch (50 mg g-1) and maximum content of amylose (39 mg g-1) after 24 hours of soaking. Alpha-amylase acts on starch and breaks into glucose molecules, which may be due to the hydrolysis of starch to glucose and maltose by the alpha amylase enzyme. Soaking of alpha-amylase enzyme at 1250 ppm has recorded the minimum content of starch of 32 and 39 mg g-1 in the whole as well as cut tubers, respectively. Thus the hydrolytic enzyme, alpha-amylase effectively degraded the food reserve leading to death of tubers before emerging out.