After years of graduate research, I have discovered what Native American farmers have likely known for millennia: landrace maize receives more benefit from beneficial soil organisms than hybrid maize.
Commercial hybrids of grains, fruits and vegetables have been selected for certain characteristics such as high yield, fruit color or taste and resistance to disease. Basically they are the offspring of the parents with the most desired characteristics. However, one drawback is that they are usually selected under optimal growing conditions and are expected to be planted in nutrient rich soils that have been supplemented with water and fertilizers.
Landrace crops and produce on the other hand are selected in dry, low-nutrient soils and are adapted to the local environmental conditions of their origin. As a result, landrace crops are generally hardy and well adapted to the environment.
Have hybrid seeds through extensive selective breeding and adaptation to high water and nutrient conditions, lost their ability to benefit from local soil organisms? Also, can some of the “hardiness” observed in landrace plants be explained by benefits received from soil organisms?
I found that under low nutrient conditions, in the presence of the beneficial soil organisms, landrace maize grew better than hybrid maize. I can attribute this difference to the soil organism-maize interaction and not to the superior genetics of the landrace maize alone because the landrace maize did poorly when grown in the same low nutrient soil without the beneficial living soil organisms.
Hybrid maize received benefit from the presence of the living organisms in the soil, but not to the magnitude that landrace maize did. In the end I can say that Native maize seeds benefit more from living organisms in the soil than do hybrid maize.
In a side-by-side comparison, landrace maize outgrew hybrid maize in mean shoot dry weight when grown with mycorrhizal fungi and other soil organisms than when grown without mycorrhizae. The ratio of plant weight with mycorrhizae to its weight without mycorrhizae is called mycorrhizal dependency, or the amount of growth that can be attributed directly to the presence of these beneficial soil fungi.
Mycorrhizae (my-co-rye-zee) are symbioses between plant roots and soil dwelling fungi. In this partnership, the fungus delivers water and nutrients from the soil in return for carbon the host plant has in excess from the process of photosynthesis.
A good trading partnership is one where the host plant receives a benefit by growing in the presence of mycorrhizae. Often this benefit is measured in plant growth or yield. However, sometimes plants do not benefit from their associations with mycorrhizal fungi and other naturally occurring soil organisms. The goal of my graduate research has been to try to understand the circumstances when mycorrhizae are beneficial and when they are not.
Natives and the white settlers have been trading partners for centuries. Native plants and soil organisms have been trading partners for millions of years. As it turns out this trading partnership between native plants and soil organisms is a good one, and a good partnership can stand the test of time.
(Ted Martinez is finishing his master’s of science degree at Northern Arizona University in environmental sciences and Policy, where he studied the role of arbuscular mycorrhizae in production and traditional Native American agriculture.)