Agriculture Publications

Getting To The Root Of Improved Fruit And Vegetable Production

By: Lauren María Alexander (Excerpt from Growing Produce, September 2016)

Link to Original Article: http://www.growingproduce.com/vegetables/getting-to-the-root-of-improved-fruit-and-vegetable-production/

Taking a holistic approach to soil health is a key to increasing plant vigor and yields. High yields begin with healthy soil, and maintaining a proper balance between nutrients, microorganisms, and other compounds is an essential part of the soil health equation.

Mycorrhiza, which describes the symbiotic association between plants and a specialized root fungus, plays an important role in enhancing plant performance and growth.

Through this mutually beneficial relationship, mycorrhizal fungi colonize plants roots, enabling the roots to access nutrients and water that may otherwise be unavailable to plants.

Mike Amaranthus, founder of Mycorrhizal Applications, which focuses on the research and development of mycorrhizal inoculum for commercial use, explains exactly how these beneficial fungi work, and how you can use them to help improve overall plant health and increase yields.

What Are Mycorrhizae And How Do They Work?
According to Amaranthus, the relationship between mycorrhizae and plant roots has been active for approximately 460 million years, and between 85% to 90% of plants form this relationship in their natural habitat.

“It’s one of those relationships where both the plant and the fungus benefit,” Amaranthus says. “The mycorrhizae benefit the plant in allowing it to access nutrients and water that are essential for the plant’s performance and growth. In turn, the fungus depends on the plant for sugars from the plant roots, which give it the energy it needs to grow into the soil.”

The fungi act as “roots of the roots” and are fine threads that grow off of the roots themselves, Amaranthus says. They are especially important in the uptake of phosphorous, nitrogen, calcium, magnesium, and other key micronutrients that may be bound up organically or on soil particles.

Weed, Disease, And Drought Benefits
Not all plants form mycorrhizal associations, including crops such as kale, spinach, Brussels sprouts, canola, mustard, and sugar beets. But on the plus side, some of the world’s worst weeds do not form mycorrhizal associations either, Amaranthus says.

“Weeds come in following a disturbance in the soil, and disturbances knock out the mycorrhizae. Without mycorrhizae, the weeds get a competitive advantage and are better able to access phosphorous in the soil. If mycorrhizal fungi are established, you can help starve weeds of phosphorous,” he explains.

Regarding disease resistance, Amaranthus says that like many other fungi, mycorrhizae produce antibiotics, which are capable of deterring root pathogens. They also have the capacity to selectively transport salt and toxic compounds away from plant roots.

“They depend on the roots for their energy source, so they want to keep the roots healthy, active, and growing. For this reason, the salt and the toxic compounds don’t get translocated to their cells,” he says.

Mycorrhizae’s benefits include drought protection due to roots’ improved ability to extend further into the soil to access water.

“Mycorrhizal roots are a lot spongier because they can get more water out of the soil, and they store them in specialized cells. They’re also much thinner so they can get into the small spaces in the soil where water is being held,” Amaranthus says.

A study Amaranthus conducted that was repeated by the University of California, Davis in 2013 showed almond trees inoculated with mycorrhizae experienced a 60% reduction in plant moisture stress.

“Some of the studies have demonstrated six or seven days of growth in drought situations,” he says.

Application Methods
Mycorrhizae can be applied to the soil in granular, powder, and liquid forms.

“We grow the seeds of the mycorrhizae, or what we call propagules. Mycorrhizal inoculums come in powder or granular forms. Growers can add water to the powder and add mycorrhizae in the liquid form near the seed, they can coat the seed with the powder, which puts the inoculum right where the roots come out of the seed, or they can band the granular material in furrow,” Amaranthus says.

To maintain populations, he says that any practice that fosters root growth will foster mycorrhizal development. Mycorrhizal development is most rapid when soil temperatures are between 40°F to 70°F and when soil fertility levels are moderate. Fumigation eradicates mycorrhizal development and re-inoculation should be at least two weeks following fumigants.

“With mycorrhizae, the bottom line for the end user is that they can get improved yields with less inputs. It’s a win-win situation,” Amaranthus says. “There’s an opportunity to save money, and it improves the efficiency of the plant’s ability to feed itself.”

Link to Original Article: http://www.growingproduce.com/vegetables/getting-to-the-root-of-improved-fruit-and-vegetable-production/ 

COPYRIGHT 2016 Growing Produce


The Dirt on Biodiversity: Mycorrhizal fungi essential to healthy vineyard soil

By Jessica Cortell (excerpt from Oregon Wine Press)

Link to Original Article: http://www.oregonwinepress.com/dirt-biodiversity 

How often do we contemplate the biodiversity of soils and what it means to healthy vineyards and for that matter, a healthy planet? The main four components of soil are water, air, minerals and organic matter. The organic component of soil is around 3 to 10 percent in Willamette Valley soils but is often overlooked in its importance.

Living soil microorganisms are less than 5 percent of the total organic component. Soils are among the most diverse ecosystem on Earth. Soil biodiversity includes all organisms living in the soil, which can be broken down into macro, mesa and micro-fauna. They can also be organized by the functions they perform in the soil. Without us paying much attention, this multitude of organisms is carrying out many important functions right under our very own feet.

The soil microorganisms can be regarded as the “biological engine of the earth.” They are involved in most of the key functions soil provides such as nutrient uptake, nutrient cycling, soil aggregate formation, degradation of pollutants, suppression of soil-borne diseases and regulation of plant communities. Also, soil microbial processes play key roles in mediating global climate change.

What about in vineyards? What roles do these organisms play and what practices are detrimental to them? About 20 years ago, many vineyards in Oregon had the “scorched earth” look where all vegetation but the vines were killed with herbicides. Luckily, the industry has come a long way since then in understanding, improving and maintaining soil biodiversity in vineyards.

When it comes to microbes, it is all about relationships. Here we will focus on a relationship between the grapevine and a specific type of fungi. The surface area that can be explored is the key to water and nutrient uptake by grapevine roots. While large roots anchor the vine and medium roots store nutrients, the fine roots are responsible for uptake. Better yet, grapevines have co-evolved for thousands of years with arbuscular mycorrhizal (AM) fungi to assist with nutrient uptake. Fossil evidence suggests that this mutually beneficial relationship with plants appeared around 400 to 600 million years ago when plants were first colonizing land.

These fungi have a relationship with grapevines in which they trade carbohydrates from the vine’s roots for improvements in uptake of water and nutrients. The fungus actually lives inside the root and forms a fungal structure known as an arbuscule inside the root cells. Arbuscules are tree-shaped structures that are responsible for nutrient exchange between the plant and the fungus. The fungus has an extensive network of hyphae outside of the root to absorb water and nutrients.

This fungal relationship has many benefits for the grapevine, including the ability to explore and take up nutrients from a greater soil volume, the hyphae have a greater ability to take up phosphorus, the hyphae can explore smaller soil pores and the hyphae can help support healthy soil aggregation for aeration and movement of water in the soil pores.

Mycorrhizal fungi play an important role in the uptake of phosphorus. Phosphorus is important in phosphate groups in ATP and ADP, which is the energy currency used by plants and animals. In general, phosphorus levels are quite low in Willamette Valley soils, and the amount of phosphorus in the soil solution is extremely low. In addition, phosphorus movement in the soil is very slow. As plants need to take up inorganic phosphate from the soil solution, it is surprising grapevines are able to pull up much phosphorus at all. However, it is the fungi that make it happen.

Even more fascinating is that the fungal hyphae can create an extensive network and connect roots on multiple vines and other species of plants. In one study, it was shown that fungal hyphae could connect the grapevines to the cover crop growing in a vineyard and minerals were found to move via the hyphae highway from the cover crop to the grapevines (Baumgartner, 2006). This helps explain how phosphorus even at low levels in the soil can move into the vine.

Improvements in phosphorus uptake have added benefits of improving drought tolerance in grapevines. One way mycorrhizal uptake of phosphorus helps is in allowing the grapevine roots to grow deep in the soil profile to take up water instead of growing shallow near the surface searching for phosphorus.

As far as practical applications in the vineyard, growers can encourage AM fungi by planting cover crops of mixed legumes and grasses or other species (except mustards as they are detrimental) and doing minimal cultivation of the cover crops in order to minimize disruption of the hyphae. In one study, mycorrhizal colonization increased from 4.7 percent in conventional management to 15.9 percent under organic management. Synthetic phosphorus fertilizers were found to be detrimental to AM fungi. Most Oregon vineyards plant cover crops regardless of the production system and use minimal amounts of synthetic fertilizers.

For new plantings, using field-grown vines are preferred as they will already have associations with mycorrhizae fungi. For potted vines grown in sterile media, they could be inoculated at planting but another approach is to grow a cover crop in the soil prior to planting the vines so the AM fungi will already be present in the soil and can colonize the young vines quickly.

Link to Original Article: http://www.oregonwinepress.com/dirt-biodiversity 

COPYRIGHT 2015 Oregon Wine Press

 


Almond Study and Drought Resistance

Establishing almond seedlings on sites where water is limiting will reduce the size and vigor of an orchard plantation and subsequently lengthen the period of time to almond production. This study found that almond seedlings inoculated with mycorrhizal inoculum exhibited a greater capacity to withstand drought conditions during early plant establishment. These findings suggest that on sites where rainfall is low or irrigation is intermittent, inoculating seedlings prior to planting in a nursery or orchard site would be beneficial.

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A Plant Evolution Revolution

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Soil biology has emerged over the last decade as a critical part of the knowledge base for successful and sustainable agricultural production. A key component of biology is the profound plant/mycorrhizal fungi relationship, which has enormous potential for improved management of contemporary farming systems. Although using these fungi has the potential to revolutionize agriculture they are certainly not new in terms of the evolution of plants.


What are Mycorrhizal Fungi video

What are Mycorrhizal Fungi

This brief animation shows how mycorrhizae work and how mycorrhizal fungi attach to roots, explore the soil and absorb vital nutrients for plants.