This Is AuburnElectronic Theses and Dissertations

MBI-3X Bio-Nematicide Plant Health Effects on Root Crops




Hoang, Linda

Type of Degree

Master's Thesis


Crop Soils and Environmental Sciences


MBI-3X is a new nematicide formulated from fermented and killed microbial broth. The broth contains large amounts of dead cells and an array of secondary metabolites in the fermentation supernatant with a corresponding array of potential effects on plants and agricultural pests. Some of these metabolites have been observed to have phytotoxic or herbicidal effects on plant tissue when applied at high rates. However, preliminary observations also suggest there may be positive plant health effects in certain species, particularly root crops. If MBI-3X is confirmed to promote plant health, this could be the result of fertilization by the nutrient broth, hormesis, or some unpredicted factor. Experiments were conducted to confirm the existence of plant health effects on selected commercially important underground plant structures such as radish (Raphanus sativus), sugar beet (Beta vulgaris), onion (Allium cepa), and other root crops. The nature of plant health effects was represented by collecting data on yield and phenology, above and below-ground biomass, root area and root size distribution. MBI-3X was found to have some bio-stimulant activities on some of the crops used, but results were inconsistent between repetitions. Most crops exhibited increase in fine root tip and lengths with the addition of MBI-3X. An extended hormesis curve was observed on the second repetition of narcissus. This may be due to secondary metabolites herbicidal effect at 100 times the standard field rate. Abiotic stressors, microclimate, and other factors may cause for the inconsistent results. MBI-3X did exhibit bio-stimulant tendencies with most of the crops. Fertilization by the liquid nutrient broth can also be a contributing factor to the plant growth effect. MBI-3X was not confirmed to have plant health effects for the selected root crops.