Effects of seed inoculation by Rhizobium strains on chlorophyll content and protein percentage in common bean cultivars (Phaseolus vulgari s L.)

To study the effect of Rhizobium inoculation treatments (inoculation with strains number 133, 116 & their integrated application)and chemical nitrogen fertilizer application(based on soil analysis in form of Urea)on chlorophyll content and protein percentage of three common bean cultivars (viz. Bahman, Darkhshan and Sayyad) a field experiment was conducted at Agricultural Research Farm of College of Agriculture, University of Tehran (Karaj, Iran) during 2010 and 2011 growing seasons. The treatments arranged as factorial based on a randomized complete block design with three replications.The characteristics such as seed and leaf protein percentage, total chlorophyll content at flowering and podding stage were measured. The highest seed protein percentage of 28.02 was produced by Sayyad cv. when inoculated by rhizobium strain 116. The Darakhsan cv.treated with rhizobium strain 116 produced the highest leaf protein(27.67%)a compared to other fertilizing treatments.The highest total chlorophyll content (1.3 mg/gr) was measured in plants inoculated by Rhizobium strain 116. In response to an interaction effect, Drakhshan cultivar produced the highest total chlorophyll content (1.56 mg/gr) when treated by chemical nitrogen fer tilizer. This could be explained by better access and easier nitrogen absorption in chemical nitrogen fertilizer treatment. The better vegetative growth in plants inoculated by rhizobium strains because of better access to nitrogen sources could stimulate other growth characteristics like total chlorophyll content in leaves. The results of this experiment suggest that application of rhizobium strains have the best effect on chlorophyll content and seed percentage.