Bioefficacy of herbicides on weeds and yield of soybean [Glycine max (L.) merrill]
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Date
2014
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JNKVV
Abstract
The present study entitled “Bioefficacy of herbicides on weeds and yield of soybean [Glycine max (L.) Merrill]” was conducted at ‘The farm’ College of Agriculture, Tikamgarh during Kharif, 2012 with the objective to study the efficacy of herbicides on weed density and weed biomass, yield attributes, yield and economics of soybean. The present experiment was carried out on cleyey soil which was Medium in organic carbon, low in available nitrogen and phosphorus and medium in potassium content and neutral in reaction.
The experiment was laid out in “Randomized block design” with twelve treatments replicated thrice. The treatments comprised of pre emergence herbicides viz. pendimethalin (1 kg a.i. ha-1), post emergence treatments imazethapyr @ 50 kg a.i. ha-1, quizalofop-ethyl@ 50 kg a.i. ha-1, chlorimuron-ethyl @ 9 kg a.i. ha-1, two hand weeding at 20 and 40 DAS and weedy check. The soybean variety “JS-335” was sown with seed rate of 80 kg ha-1 with fertilizer dose of 20:60:30 kg ha-1. Pre emergence herbicides were applied on next day of sowing. Different observations on weeds and crop parameters were recorded during the course of investigation at 25, 50, 75 DAS and at harvest stage.
The major weed species observed in the experimental area were Cynodon dactylon, Cyperus rotundus, Convolvulus arvensis, Saccharam spontaneum, Phyllanthus niruri and Commelina benghalensis. The relative density of monocots was 62.71 % while dicots were to the extent of 30.60 % of the total weed population.
All the herbicidal treatments, hand weeding and hand hoeing reduced the weed intensity as well as weed biomass compared to weedy check. Hand weeding twice was most effective and recorded minimum weed intensity and biomass among all the treatments. Application of quizalofop-ethyl @ 50 g a.i. ha-1 and its combination fb hand hoeing at 40 DAS, chlorimuron-ethyl and pendimethalin recorded lower weeds than all combination of pendimethalin whereas in pendimethalin fb one hand weeding at 20 DAS registered significantly lower weed intensity than chlorimuron-ethyl @ 9 g a.i. ha 1 + quizalofop-ethyl @ 50 g a.i. ha 1. Hand weeding superseded over all the treatments and attained minimum weed biomass of (7.18 g m-2) with weed control efficiency of 90.89 % followed by pendimethalin fb one hand weeding at 20 DAS (86.51 %).
All the crop growth parameter like leaf area index, number of branches plant 1 crop growth rate, and net assimilation rate were significantly higher under two hand weeding followed by pendimethalin fb one hand weeding at 20 DAS and quizalofop-ethyl than pendimethalin and weedy check. Yield attributing characters viz; number of pods plant-1, number of seeds pod-1 , seed weight pod 1 , seed yield plant 1 and test weight attained significantly higher values under herbicidal treatments, hand weeding and hand hoeing than weedy check.
Seed yield, straw yield and harvest index was significantly higher under all the weed control practices over weedy check. Two hand weeding at 20 & 40 DAS recorded the higher seed yield (1834.33 kg ha-1) among all the treatments followed by pendimethalin fb one hand weeding at 20 DAS (1791.0 kg ha-1). Among the herbicides, application of pendimethalin fb quizalofop-ethyl (1745.51 kg ha-1) and chlorimuron-ethyl + quizalofop-ethyl (1740.68 kg ha-1) produced significantly higher yield over application of chlorimuron-ethyl.
The highest gross monetary return was obtained two hand weedings whereas the B:C ratio and net monetary return was the highest with the application of chlorimuron-ethyl + quizalofop-ethyl followed by pendimethalin fb quizalofop-ethyl and pendimethalin fb imazethapyr.
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Keywords
weeds, control methods, herbicides, yields, soybeans, cultivation, sowing, drying, planting, harvesting