radiation absorption and use efficiency of sesame as affected by biofertilizers in a low input cropping system

cultivation of high efficacy crops in resource utilization, especially with higher water and radiation use efficiencies is one of the important strategies to achieve the goals of sustainable agriculture. align with these guidelines and in order to estimate light extinction coefficient and radiation use efficiency of sesame a split plot arrangement of two factors based on randomized complete block design with three replications was conducted in 2009-10 growing season. cultivation and no cultivation of lathyrus sp. and persian clover (trifolium resopinatum) as cover crop 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. &azospirillum; sp. ), 2- biophosphor psb (containing of phosphate solubilizing bacteria,bacillus sp. &pseudomonas; sp. )), 3- biosulfur ssb (containing of thiobacillus ssp. ) and 4- control (no fertilizer). the results showed that application of biofertilizers resulted to 15 days shorter period to achieve maximum leaf area index compared to control and as a result, the maximum fraction of absorbed radiation and consequentlysesame dry matter produced at the sixtieth day after emergence, 15 day sooner than control. sesame dry matter production after cover crops cultivation was 19 percent higher than no cover crop cultivation treatment. although, light extinction coefficient in control (no biofertilizer) was higher than biofertilizer treatments (0. 78 vs. 0. 69), but radiation use efficiency (rue) in biosulfurand nitroxin was higher compared to control (1. 31 , 1. 24 and 1. 09respectively) which resulted to highest biological and seed yield and harvest index. sesame radiation use efficiency in plots with cover crop was 0. 18 higher than plots with no cover crop. in this research, the total mean sesame rue estimated of 1. 19 gmj-1 (r2=0. 95). in general, these results indicated that application of nitroxin and biosulfur combined with cover crops cultivation enhanced utilization of radiated and absorbed radiation by sesame canopy and consequently improved yield.