Studying of integrated weed management in rainfed chickpea (Cicer arietinum L.)

Chickpea is important due to its grain high protein. Chickpea is weak to compete with weeds because of the retard growth at the early stages. Therefore, weed control at this time plays an important role to gain high production. Chickpea is being grown in both dry land and irrigated systems, and growers in both systems are finding weed control to be a major obstacle to profitable production. Weed control is essential for maximum seed yield and seed quality. Selection of the herbicide plus cultivator between rows can effectively control weeds. Herbicide due to efficiency and cost savings play a basic role in weed management. Application of Isoxaflutole controlled weeds in chickpea fields with very low phytotoxicity on chickpea. But the risk of crop injury from Isoxaflutole has been reported to be greatest in soils with low organic matter content and high pH. The only herbicide registered for chickpea in Iran, is pyridate in 1998.Considering the importance of agriculture chickpea in Kermanshah and high cost of hand weeding in the fields, this study was projected to achieve the most appropriate herbicides in combination with mechanical methods (row cultivator), in order to optimally control weeds and increase the yield of chickpea. The objective of this research was to identify efficacious chemical weed-control plus cultivation options for rainfed production of chickpea in Kermanshah.

The experiment was carried out as strip plot based on complete randomized block design with four replications during 2014-2015 in Kermanshah province. The main factor included inter-row cultivation and without inter-row cultivation and the sub factor consisted of applications of Linuron (pre planting), Isoxaflutole (post emergence), Metribuzin (pre emergence), Paraquat (post emergence), Pendimethalin (pre emergence), Pyridate (post emergence) at rates 0.67, 0.48, 0.42, 0.05, 0.82, 1.5 kg a.i./ha respectively and hand weeding. Chickpea (ILC482) were sown on March 3th placing 45 seeds m-2 in rows 0.6 m apart. All herbicides were sprayed with an Elegance 18 electric knapsack sprayer equipped with flooding nozzle and calibrated to deliver 300 L/ha of spray solution at a pressure of 2.5 bar. Herbicides were applied in one-half of each plot, and the other half kept as its control. The inter-row cultivation was applied on April 29th 2014.  Percent weed population and biomass reduction in all treatments was measured separately for each weed species by counting the number of weeds 30 days after treatment within two fixed 1m2 quadrates that were dropped in the treated and untreated halves of each plot. The data were subjected to the analysis of variance using SAS. Means were compared using Duncan's Multiple Range test at P=0.05 level of significance.

Results showed that cultivation between rows reduced population of Lambs quarters and Redroot Pigweed significantly. Linurin and Paraquat could not provide acceptable biomass and population reduction. But Pyridate, Isoxaflutole and Metribuzin could control satisfactorily weeds. None of herbicide treatments could reduce Field binweed populations satisfactorily, so that the highest population reduction was observed in Lambs quarters (100%) where sprayed with Metribuzin. Percent total weed density reduction by pyridate and Isoxaflutole was highest (78% and 57%). Metribuzin reduced total weed density by at least 71%. Hand weeding plus cultivation, Pyridate plus inter-row cultivation and pyridate, caused chickpea grain yield to increase by 44.83%, 44.46%, 40.58% respectively compared with weedy check. Isoxaflutole plus inter-row cultivation and Isoxaflutole caused chickpea grain yield to increase 37.18% and 34% respectively. The highest chickpea phytotoxicity (30%) was achieved where Linuron applied.

Overall results showed that pyridate at rate 1.5 kg a.i./ha is a suitable option for control of weeds and increasing the chickpea grain yield. The results also showed that inter-row cultivation had no significant effect on weed reduction and grain yield by pyridate and Isoxaflutole. In this study, isoxaflotle controlled a wide range of weeds. It is suggested that further studies be carried out on the use of this herbicide at different times of application (pre emergence and post emergence) and different amounts.