effect of mycorrhiza fungi and humic substances on yield and yield components of corn (zea mays l. var. s.c. 704) under limited irrigation condition

to study the effects of mycorrhiza fungi and humic substances on yield and yield components of corn (zea mays l. var. s.c. 704) under limited irrigation condition, an experiment was conducted in split plot arrangement based on rcbd in four replications at the research farm of university of tehran (karaj-iran) in 2011. the main factor consisted of three irrigation levels i.e. normal (irrigation every 7days); mild water stress (irrigation every 10days) and severs water stress (irrigation every 14days). fertilizer treatments comprised of zero (control); application of phosphorus 50% (based on soil testing result); application of phosphorus 100%; phosphorus 50% plus mycorrhiza; phosphorus 50% plus humic substance; and phosphorus 50% with humic substance plus mycorrhiza. the results showed that water stress significantly decreased yield. the fertilizer treatments had significant effects on grain yield, biological yield, and plant height, grain protein, grain nitrogen and phosphorus; but had no significant effect on seed weight, and harvest index. comparison of treatment means for different traits showed that the greatest change compared to the control, was for the treatment of 50% humic compounds plus phosphorus fertilizer with mycorrhizal fungi.