Evaluation the efficacy of Pyridate combination with some graminicide for weed control in chickpea (Cicer arietinum L.)

Chickpea is the second important legume crops and because of high protein level (18-30 percent), has a key role in human diet. Chickpea is a weak competitor and one of the most sensitive legumes to weed interference because of its slow growth at the seedling stage, low height and slow canopy closer. Growing chickpea in weedy condition can suffer yield reduction up to 40 to 90 percent and weed management is one of the most important agronomy management in chickpea cultivation. Among weed control methods, chemical control is the most important method. Today only a few herbicides are registered for broadleaf weed control of chickpea and most of them are preemergence. Pyridate is one of the important herbicides registered as a post herbicide for broadleaf weed control in chickpea. However chickpea weeds contains a wide range of broadleaf and grasses. Grassy weeds are the weed flora of chickpea farms and pyridate cannot control them. In Iran we don’t have any dual purpose herbicide to control broad spectrum of weeds. Framers use common graminicides like haloxyfop-methyl and sethoxidim and also broadleaf herbicides specially pyridite in chickpea farms and there is no information on the possibility of simultaneous use of graminicide herbicides and pyridate using the herbicide mixing approach. The aim of this study was to investigate the possibility of combination of pyridate herbicide with haloxyfop-methyl, cycloxidim, clethodim and sethoxidim graminicides for weed control in chickpea cultivations.

The experiment was conducted as completely randomized block design with three replications at Research Farm of Ferdowsi University of Mashhad, Iran, during 2015. The investigated treatments including application of pyridate, clethodim, sethoxidim, haloxy-fop methyl and cycloxidim alone and application of pyridate with mentioned graminicides in recommended doses with full season hand weeding and full season weed interference as control treatments. The experiment was performed under rainfed condition and chickpea planting density was 40 plant m-2. Herbicides were applied at the two to four leaf stages of weeds. For controlling of Helliotis sp., Indoxacarb (Avant) pesticide were sprayed at recommended dose in poding stage. For evaluating the effect of treatments on weeds density and biomass, in three periods (13, 23 and 48 days after herbicides spraying) sampling was done from 0.5 m-2 area and weed density and weed biomass recorded. At the end of growing season and when chickpea was matured, 40 chickpea plant were harvested randomly in each plot and after drying for 48 hours exposed to sunlight, chickpea biomass and seed yield were measured. After normality test, data statistical analysis were performed by SAS Ver 9.1 and means were compared by Dunkan test at 5% probability level.

Results indicated that herbicides combination reduced weed density and weed biomass in all sampling periods and also increased seed yield and biomass of chickpea. Because of broadleaf weed dominance in the studied farm, application of pyridate was not significant difference with herbicide combination and graminicides showed the weakest weed control measure between treatments. Best weed density and weed biomass control during the growing season were observed in combination of pyridate plus haloxy-fop methyl. Among the treatments, combination of clethodim+ pyridate and cycloxydim+ pyridate had higher chickpea seed yield (945 kg.ha-1) and chickpea biomass (3700 kg.ha-1), respectively. The effect of herbicides on weed density and weed biomass was more effective at first sampling period than next sampling periods. It seems this is because of the mode of action of applied herbicides. Pyridate is a contact herbicide and others are systemic with no activity in the soil and to end of the growing season, herbicide efficacy become weak and not effective. None of the herbicides were harmful to chickpea either they applied alone or in combination together.

 So, with considering the dominant weed flora in chickpea farms, we can choose the best option of herbicide application method for weed control in chickpea farms. If broadleaf weeds are dominant in the farm, we can use pyridate alone, if the farm is dominated with grassy weeds, we can use haloxy-fop methyl. So, in the farm that considered the grasses and broadleaf weeds, we can use pyridate combination with any graminicides, but between combinations, the best yield and weed control achieved in the pyridate plus haloxy-fop methyl combination.