184 J. Crop and Weed, 13(3) Zinc oxide nanorods to degrade phenolics and stored starch of Cyperus rotundus tubers management K. BRINDHA AND 1 C. R. CHINNAMUTHU Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore – 641003 1 Department of Agronomy, Agricultural College and Research Institute, Madurai – 625104 Received : 16-02-2017 ; Revised : 14-11-2017 ; Accepted : 20-11-2017 ABSTRACT The lab experiment was conducted during 2011-12 on purple nutsedge (Cyperus rotundus) to induce the sprouting of buds by degrading the phenolic compounds and exhausting food reserve to reduce the multiplication rate of tubers with Zinc oxide nanoparticles. Zinc oxide nanoparticles (ZnO) were synthesized by wet chemical method characterized with Transmission Electron Microscope, Scanning Electron Microscope, Particles Size Analyzer, Raman Spectrometer and studied their effect on the degradation of phenols, starch, amylose and germination of dormant buds with different concentrations. A standardization experiment was taken up at the preliminary level with different dosages of ZnO in wet and dry conditions to scale down the treatments to a manageable level of thirteen including the control in each of the nanoparticles used. Results revealed that the presence of high amount of phenol (10.5 mg g -1 ) in the control treatment, no germination (0%) was recorded whereas the ZnO treated tubers at the rate of 1500 mg kg -1 registered the lower content of phenol (6.0 mg g -1 ) and the higher percent of germination (80%), longer root, shoot length (20.43 cm, 29.00 cm) and higher vigour index (3954) in dry method. In case of wet method, higher amylose content of 52.0 mg g -1 , lower content of starch (108.0 mg g -1 ) , phenol(4.2 mg g -1 ) with 80 per cent germination, longer root, shoot length (20.00 cm, 29.00 cm) and higher vigour index (3920) was noticed with the concentration of 2250 mg kg -1 . The untreated tubers (control treatment) recorded lower amylose content (10.0 mg g -1 ) with higher phenol (9.9 mg g -1 ) and starch content of 148.0 mg g -1 with 20 per cent germination. Keywords : Biochemical components, purple nutsedge tuber, zinc oxide nanoparticles The demand for food crops is increasing day by day and we are in a situation to feed the growing population. However the plants out of place growing along with crop plants known as weeds became one of the major threats to limit the yields. Suitably managing this limiting factor will certainly accomplish the production and productivity of crops and preserve the natural resources. Charles (1997) reported that the purple nutsedge is considered as one of the worst weeds of the world widely distributed throughout the tropics and subtropics in 52 different crops and in 92 countries. It ravages the cultivated fields very quickly and causes one hundred per cent yield loss at times. Bryson et al. (2003) reported that the purple nutsedge is highly competitive and causes yield reductions of various crops ranging from 23 to 89 per cent and particularly 62 to 85 per cent reduction of seed cotton yield compared with no purple nutsedge infestation. Management of this weed will be one of the major tasks because of its perennial nature. Many cultural and chemical methods were tried to manage Cyperus spp., however the results are not encouraging. Accumulation of phenolic compounds during the stress condition prevents the germination of tubers to tide over the unfavourable condition. Further the poor translocation of foliar applied herbicides kill only the primary tubers leaving the others in chain unaffected lead to enlarging of weed seed propagules reserve as season advances. Therefore the nutsedge management strategies must include a long- term commitment to prevent the new tuber formation, breaking the dormancy and killing the viable tubers. In order to have a better insight into the work done already on biology, competitive nature, control measure taken in the recent past and the possibilities with the new science, the nanotechnological applications to manage this perennial sedge weed. Hence, the present study was carried out to evaluate the zinc oxide nanoparticles mediated breaking of dormancy and exhausting the food reserve in the tubers of Cyperus rotundus. A laboratory study was conducted at the Department of Nano Science and Technology, Tamil Nadu Agricultural University during 2011-12. Tubers of purple nutsedge (Cyperus rotundus) collected in bulk from the garden lands of Velampatti (11°9’29"N 78°21’54"E), Trichy district, Tamil Nadu during 2011- 2012 formed the base material for the study. The Zinc oxide (ZnO) nanoparticles were synthesized in the laboratory through chemical routes. For which 0.45 M aqueous solution of zinc nitrate Zn (NO 3 ) 2 .4H 2 O and 0.9 M aqueous solution of sodium hydroxide (NaOH) were prepared in distilled water. Then, the beaker containing NaOH solution was heated to the temperature of 55 ºC. The Zn (NO 3 ) 2 solutions were added drop wise (slowly for 40 min) to the above heated solution under high speed stirring. The beaker was sealed at this condition for two hour. The precipitated ZnO nanoparticles were cleaned with deionized water and ethanol then dried in atmospheric air at about 60 ºC. Journal of Crop and Weed, 13(3): 184-188 (2017) Short communication Email: bindiya14@gmail.com