ROLE OF SENESCENCE AND ADJUVANTS IN HERBICIDE ON ITS EFFICACY AND SPROUTING ABILITY OF Cyperus rotundus L.
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Date
2010-07-16
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University of Agricultural Sciences, Bangalore
Abstract
Cyperus rotundus is one of the most noxious weed which propagates through underground plant parts (tubers).Controlling this weed by herbicide more effective than hand weeding. Glyphosate is an eco-friendly with no residue in soil, less mammalian toxicity, high water solubility, highly translocative and non-selective herbicide widely used in wide spaced horticultural crops by directing the spray. It was observed that in resistant weed species lack of translocation from fed leaf to meristematic apex is one of the mechanism to cause resistance. Studies showed that senescence induced by glyphosate increases the 14C-glyphosate and 14C-2,4-D translocation and its efficacy. Several experiments were conducted to standardize the duration and dosage of glyphosate to induce senescence. Senescence followed by herbicide application substantially reduced sprouting ability of tubers as reflected by reduced number of shoots
produced per tuber both in non-dormant and dormant tubers of Cyperus rotundus. The ideal duration found to induce senescence is 48hr and 8ml/lit of glyphosate concentration followed by 8ml/lit of glyphosate is the best dosage to control Cyperus rotundus. Leaf
chlorophyll content, membrane integrity and relative water content were affected by glyphosate, ethephon and paraquat and repair mechanism of membrane and higher RWC after 48hr of glyphosate to induce senescence proved to be more effective than other
senescence agents. Glyphosate along with adjuvant (jaggery 1%) application showed, to enhance the herbicide efficacy and reduce tuber viability of Cyperus rotundus drastically. The tubers exposed to higher temperature (750C) either by hot water irrigation to pots or dipping in hot water or exposing tubers to hot air oven for 30minute were lost their viability (TTC test- 2, 3, 5- Triphenyl Tetrazolium Chloride). Different formulation of glyphosate, Roundup (8ml/lit) isopropyl amine salt (41%EC) and Meera 71(10gm/lit) ammonium salt of glyphosate (71% SG) had same efficacy. However Sure shot (0.03%) with Meera 71 enhanced the efficacy 1.33 fold of Meera 71 in control of Cyperus rotundus.
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