Investigate the effect of Pyridate, Bentazon and Imazethapyr herbicides on growth, nodulation and biological nitrogen fixation in chickpea (Cicer arietinum L.)

In order to study the effect of Pyridate, Bentazon and Imazethapyr herbicides on chickpea growth, nodulation and biological nitrogen fixation, a greenhouse experiment was conducted at Ferdowsi University of Mashhad in 2010. Experimental type was completely randomized design with four replications. Treatments included Pyridate, Bentazon and Imazethapyr herbicides application in 1200, 720 and 75 ga.i./ha-1, respectively. Chickpea seed inoculation with Mesorhizobium ciceri bacteria in two levels (inoculated and non-inoculated) and two levels of soil sterile and non-sterile. Seeds planted in pots with 10 cm diameter. Pyridate was applied as preplant and soil in corporation, but Bentazon and Imazethapyr were applied at third pinnately leaf. At 40 days after herbicides application (flowering stages), plant survival, root and shoot biomass, root/shoot ratio, nodule number, nodule dry weight and chickpea nitrogen fixing parameters were determined. Results showed that seed inoculation with Mesorhizobium increased nodule number and its dry weight, 20 and 25 percent, respectively. Soil sterilization decreased nodule number, nodule dry weight, nitrogen fixing and root/shoot ratio, significantly (P< 0.01). Based on experimental results of all herbicides, application decreased significantly (P< 0.01) in above mentioned parameters. Among herbicides, Bentazon imposed the most negative effect on chickpea parameters, and decreased root and shoot biomass and nodule number and weight as 80%, 73%, 93% and 97%, respectively. However, Pyridate herbicide had the lowest effect on nodule number, nodule dry weight and nitrogen fixation, but it decreased chickpea root and shoot biomass, significantly. Imazethapyr had lower effect on chickpea root and shoot biomass, but it imposed the most negative effect on nodule number and nodule weight.