Studies on bioefficacy of tembotrione in controlling weeds in maize and its residual effect in wheat and sarson

Abstract

newlineThe field experiment was conducted during 2014-15 and 2015-16 at Palampur to evaluate the bioefficacy of tembotrione in controlling weeds in maize and its residual effect in wheat and sarson. The soil of the test site was silty clay loam in texture, acidic in reaction, high in organic carbon and P, medium in K and low in N. Sixteen weed control treatments comprising 3 doses of tembotrione (110, 120 and 130 g/ha) alone and with surfactant (isoxadifen-ethyl, 1000 ml/ha) at 2 and 3 weeks after sowing (WAS) along with farmer s practice, atrazine 1.5 kg/ha, weed free and weedy check in maize during kharif each year as main factors were tested in randomized block design with three replications. During winter season all these sixteen treatments considered in main plots and three treatments (unweeded check, isoproturon 1.25 kg/ha and hand-weeding (30and60 DAS) in wheat and unweeded check, pendimethalin 1.5 kg/ha and hand-weeding (30and60 DAS) in brown sarson) each in wheat and brown sarson in sub plots were in split plot design with three replications. Echinochloa colona and Commelina benghalensis were the major weeds constituting 25.7 and 23.2 per cent, respectively of the total weed flora in maize during kharif season. This was followed by Ageratum conyzoides (13.7%), Cyperus iria (15.1%), Aeschynomene indica (9.4%) and Galinsoga parviflora (8.0%) and other weeds (5%). Among treatments applied in maize, post emergence application of tembotrione 130 g/ha along with surfactant at 21 DAS was as effective as weed free to control the grassy as well as non-grassy weeds. Tembotrione 130 g/ha with surfactant at 21 DAS resulted in lowest weed index (5.4, 4.7%) and highest weed control efficiency (83.9, 82.0%) during both the years. Significantly lowest N, P and K uptake by weeds were obtained with weed free followed by tembotrione 130 g/ha + surfactant at 21 DAS during both the years. Tembotrione 130 g/ha with surfactant at 14 and 21 DAS was comparable to weed free in increasing yield attributes and grain and stover yield of maize during both the years. Addition of surfactant (1000 ml/ha) significantly increased the grain yield and reduced the density of weeds effectively as compared to the application of tembotrione without surfactant. Dehydrogenase activity in soil decreased for applied herbicide concentrations from 20 to 60 DAS. However, at later stages of the crop growth (60, 80 and 100 DAS), there was a drastic increase in the activity of newline12 newline12 newlinedehydrogenase enzyme in all the treatments. CGR and RGR were significantly higher in tembotrione 130 g/ha at 21 DAS as compared to other treatments. Weed free being at par with tembotrione 130 g/ha + surfactant at 21 DAS resulted in significantly higher N, P and K uptake by maize crop during both the years. No residual effects were observed on the growth and yield of succeeding wheat and brown sarson crops and weeds associated therein. newlineAnagallis arvensis and Phalaris minor were the major weeds constituting 29.6 and 24.7 per cent, respectively of the total weed flora in wheat during rabi season. This was followed by Vicia sativa (15.2%), Trifolium repens (12.8%), Spergula arvensis (11.3%) and other weeds (6.6%). In brown sarson, Phalaris minor and Lathyrus aphaca were the major weeds constituting 43.9 and 24.3 per cent, respectively of the total weed flora. This was followed by Vicia sativa (19.5%) and other weeds (12.4%). In wheat, hand-weeding (30and60 DAS) followed by isoproturon 1.25 kg/ha was found to be effective for controlling weeds and increasing yield attributes and yields as compared to weedy check. In brown sarson, hand-weeding (30and60 DAS) followed by pendimethalin 1.5 kg/ha was also found to be effective for controlling weeds and increasing yield attributes and yields. In maize, net returns over weedy control/check were highest in weed free followed by tembotrione 130 g/ha + surfactant at 21 DAS during both the years. Marginal benefit cost ratio was highest in tembotrione 130 g/ha + surfactant at 21 DAS followed by tembotrione 130 g/ha + surfactant at 14 DAS during both the years. In maize-wheat and maize- brown sarson cropping system, tembotrione 130 g/ha with surfactant at 21 DAS was comparable to weed free for increasing gross and net returns in maize and highest B:C ratio were obtained with same treatment in maize and isoproturon 1.25 kg/ha in wheat and pendimethalin 1.5 kg/ha in brown sarson during both the years.