the effect of plant growth promoting rhizobacteria (pgpr) on quantitative and qualitative characteristics of sesamum indicum l. with application of cover crops of lathyrus sp. and persian clover (trifolium resopinatum l.)

cover crops cultivation and application of plant growth rhizobacteria are the key factors to enhance agroecosystem health. a field experiment was conducted at the research farm of faculty of agriculture, ferdowsi university of mashhad, iran, during growing season of 2009-2010. a split plot arrangement based on a complete randomized block design with three replications was used. cultivation and no cultivation of lathyrus sp. and persian clover (trifolium resopinatum) in autumn assigned to the main plots. the sub plot factor consisted of three different types of biofertilizers plus control, including 1-nitroxin (containing of azotobacter sp. and azospirillum sp.), 2- phosphate solubilizing bacteria (psb) (containing of bacillus sp. and pseudomonas sp.), 3- biosulfur (containing of thiobacillus ssp.) and 4- control (no fertilizer). the results showed the effect of cover crops on seed number and seed weight per plant, biological and seed yield was significant, as the seed yield increased of 9 %. in general, biofertilizers showed superiority due to the most studied traits compared to control. nitroxin, psb and biosulfur increased biological yield of 44, 28 and 26 % compared to control, respectively. cover crops and biofertilizers interactions, showed significant effect on all studied traits, as the highest and the lowest harvest index resulted in cover crop combined with biofertilizers (22.1%) and cultivation and no cultivation of cover crops combined with control (15.3%), respectively. the highest seed oil and protein content resulted from cover crops plus biofertilizers (42.4%) and cover crops plus psb (22.5%), respectively. in general, the results showed cover crops cultivation in combination with biofertilizers application could be an ecological alternative for chemical fertilizers, in addition of achieving advantages of cover crops. according to the results, it should be possible to design an ecological cropping system and produce appropriate and healthy sesame in agreement with ecofriendly agricultural production guidelines.