Companion planting effects of insecticidal marigolds and nitrogen fixing legumes on growth and protection.

Abstract

In agricultural systems, intercropping is used to increase crop yield while simultaneously reducing herbivory. In order to test the effectiveness of three reputedly effective companion species, a garden plot at UMBS was developed. This included Tagetes patula, a species known to exude a volatile insect repellant, along with Phaseolus vulgaris and Pisum sativum, two species of legumes that house nitrogen fixing bacteria. Measurements were taken over the course of several weeks on the percentage of leaf area lost due to insect herbivory, and growth in height for each plant. The results from the experiment show that there was a significant decrease in the amount of herbivory, as well as an increase in plant growth, between our intercropped and control plots. Overall the effectiveness of each plant species was supported by our data, showing that each species had a beneficial relationship with plants located in close proximity to them as thought by agriculturists for many years.