Comparison of Synthetic Versus Organic Herbicides/Insecticides on Arbuscular Mycorrhizal Fungi.

COMPARISON OF SYNTHETIC VERSUS ORGANIC HERBICIDES/INSECTICIDES ON ARBUSCULAR MYCORRHIZAL FUNGI

Ariel Freidenreich, Pushpa Soti and Krish Jayachandran

Department of Earth and Environment, Florida International University, Miami, Florida 33199

Arbuscular mycorrhizal fungi (AMF) play a crucial role in improving the growth of a vast majority of plants, including agricultural crops. Past researchers have shown that agricultural practices have a significant effect on the diversity and density of AMF. Agricultural practices in conventional farms such as use of fertilizers, pesticides, tillage, and monocultures are reported to be detrimental to AMF compared to low input agriculture systems. Additionally, AMF are reported to enhance plant nutrient uptake, stress tolerance, and soil aggregate formation which are key aspects of productive low-input farming. The objective of this study is to investigate the diversity and density of AMF spores at sites under conventional and organic farming. A high input conventional system will be used to determine the effects of chemical herbicide (glyphosate) and insecticide (carbaryl) on soil microorganisms and plant productivity. A low input, organic system will be used to determine the effects of organic alternatives (neem and citrus oil) on soil microorganisms and plant productivity.  The differences in plant growth and status of AMF from these two systems will be analyzed by growing a host crop plant inoculated with AMF spores. Insecticides and herbicides will be applied following the manufacturer's recommended dose. At the end of the experiment, crop yield, growth success (root, stem, and leaf mass ratio, and leaf nutrient status), density and diversity of AMF spores, the percentage of mycorrhizal colonization in roots, and glomalin, a glycoprotein produced by AMF, within these two land use types will be measured and analyzed to determine the influence of agricultural practice on AMF. Results from this study will provide a better understanding of how chemical herbicides, insecticides, and their organic alternatives affect soil microbiological communities, and in turn overall plant productivity.