Effect of Glyphosate on Physiology and Biochemical Properties of Purple Nutsedge (Cyperus rotundus L.)

The study was conducted to understand the influence of herbicide on the changes in physiology and biochemical properties of purple nutsedge weed (Cyperus rotundus L.). Laboratory and pot culture study were conducted at the Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during 2020-21. Glyphosate was tested with different concentrations (500, 600, 700, 800, 900 and 1000 ppm) and various soaking duration (6, 12, 24 and 48 hrs) with three replication. The extent of weed damage is based on the site of herbicide action, inhibition of enzymes activity and other metabolic functions. It resulted in chlorophyll content and membrane stability index of the weeds were affected. Proline level of treated weeds were found to be increased at initial stage of herbicide application and followed by declined gradually. It causes the weeds to kill by exhibiting oxidative stress. Phytotoxic effect of herbicide application was visualized until 15-20 DAHA (days after herbicide application) and thereafter weeds were died due to cessation of all the metabolic activities. The findings of the soaking experiment confirmed the negative impact of herbicide on phenol and starch content in tubers. Phenol degradation or dilution was observed to be increased with increasing duration of soaking period and however starch content decreases simultaneously. The results showed that application of glyphosate @ 1000 ppm is more effective to arrest the population of Cyperus rotundus.