Document Type : Research Article
Abstract
In recent years, biological fertilizers have received special attention by scientists in sustainable and low input agriculture. In order to study the effects of arbuscular mycorrhizal fungi and free living nitrogen fixing bacteria on growth and photosynthesis characteristics of corn in conventional and ecological cropping systems, a field experiment was conducted during 2005-2007. A split plots arrangement based on randomized complete block design with three replications was used. Treatments consisted four cropping systems (high, medium, and low input conventional as well as ecological system) and four inoculations (mycorrhiza fungus, bacteria, dual inoculation (fungus plus bacteria), and noinoculation (control)), which were allocated to main plots and sub plots, respectively. Dry matter (DM), seed yield (SY), leaf area index (LAI) canopy temperature (CT), soil respiration rate (SRR), root length colonization percent (RLCP), specific root length (SRL), plant and soil N, P, and K content were measured. Results showed that the lowest CT existed in ecological cropping system. The same was observed for inoculants effect on CT. SRS and RLCP were not affected by cropping systems, but
the effect of inoculants was significant, the highest SRS existed in dual inoculation. The highest SRL observed in fungus and bacterial inoculation. The effect of inoculants on plant P and K was not significant and the lowest plant N was observed in fungus inoculation. Correlation coefficients showed that, the strongest correlation obtained for DM and LAI, and between SRL and SY. The positive and significant correlation between RLCP and LAI, and between SRL and DM, emphasis that any factor increasing RLCP and SRL will increase LAI and DM, thereby, seed yield. Yield estimation model predicted that SY was determined by some variables such as LAI, CT, SRL. This study showed that utilization of low input conventional and ecological systems in combination with use of dual inoculation of arbuscular mycorrhizal fungus and free living nitrogen fixing bacteria could be a suitable alternative for high input conventional systems and chemical fertilizers.
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