Chemical and biological fertilizer management of nitrogen effects on yield and yield components of chickpea (Cicer arietinum L.) in different planting dates

Introduction Chickpea (Cicer arietinum L.) is commonly the most important food seed legume in South Asia. Nitrogen is generally a major limiting nutrient for the growth of many plants in many environments. Some plants are able to provide all or part of its nitrogen demand through biological nitrogen fixation as a result of interaction with symbiotic bacteria. Mesorhizobium have a symbiotic association with chickpea. Planting date is one of the important factors which determine the ability of the crop to stand against different environmental conditions (air, temperature and humidity) in the field, when environmental conditions are conductive for growth and development. Results obtained from other studies clearly have indicated that N application and Rhizobium inoculation had significant effects on yield and yield components. The greatest values of plant height, number of primary and secondary branches, number of pods per plant, number of grains per plant, seed yield and biological yield were obtained from the highest level of N fertilizer (100 kg. ha-1 urea) and Rhizobium Inoculation. López-Bellido et al, (2008) reported that early planting date improved chickpea yield.   Materials & Methods A field experiment was conducted on experimental farm of the Gonbad Kavous University during the growing season of 2015-2016. The experimental layout was factorial based on RCBD with three replications and three factors. Nitrogen was in four levels (no application, application of 20, 40 and 60 kg nitrogen ha-1). Planting dates was in two levels (4th of January and 1st of February) and Mesorhizobium biological fertilizer was in two levels (inoculation with Mesorhizobium and no inoculation). Half of nitrogen was used at planting and the other half was used during grain filling stage. Seeds in inoculation treatments were inoculated with Mesorhizobium, strain SWRI14, which were obtained from the Soil and Fertilizer Research Institute, Tehran. The OD’s were adjusted so that the cell concentration was 109 CFU ml-1. Plots (1.5 m × 6 m) were designed as 5 rows per plot. To determine the yield components, 10 plants were selected and traits like plant height, branch numbers, number of pods per plant, number of seeds per plant, 100-seed weight, biological yield and harvest index were recorded or calculated. Seed yield was obtained by removing of two border lines and 0.5 m of each sides of three middle rows. Comparison of means was performed by LSD test for 5% probability level by using SAS statistical software version 9.1.3.   Results & Discussion The results showed that planting date had significant effect on traits of number of stems per plant at the level of 5%, however for plant height, number of pods per plant, number of seeds per plant, seed yield and biological yield were significant at the level of 1%. These traits were higher planting date of 4 Jan. Number of pods per plant, seed yield and biological yield were significantly affected by nitrogen at 5% level. The greatest values of this trait were obtained from application of 60 kg.ha-1 of nitrogen fertilizer but did not have significant differences with 40 kg.ha-1 of nitrogen fertilizer. Mesorhizobium influenced the number of pods per plant, number of seeds per plant and seed yield at level of 1% and biological yield at the level of 5%. Mesorhizobium inoculation increased all traits. The interaction effects of factors were not significant for any of the traits. It seems that based on the correlation between these traits with seed yield, yield components had a positive and decisive role on seed yield   Conclusion The results showed that application of nitrogen fertilizer and Mesorhizobium biofertilizer due to the supply of part of required nitrogen of plant, and also early planting date due to more growth period, provided better opportunities for capturing the environmental resources and nitrogen. As a result, first planting date, use of nitrogen and Mesorhizobium inoculation increased plant growth and seed yield in this study.