Original Article: http://urbangardenmagazine.com/2011/...ponic-systems/
What is Trichoderma?
Trichoderma is a naturally occurring genus of soil fungi which has been known to possess bio control qualities against a number of plant pathogens since the 1920s. While there are a number of plant-associated microbes, both fungi and bacteria which are strongly beneficial to plants, none has been more intensively studied than Trichoderma. Stable and effective preparations of Trichoderma have also been formulated into a range of bio control or “effective microorganism” products readily available on the market for both large-scale commercial producers and smaller home gardeners. Although Trichoderma is naturally endemic to soil and decomposing organic matter, it is well proven to have significant beneficial effects in soilless systems and formulations have been developed specifically for hydroponic use. While Trichoderma can be highly effective as both a pathogen control agent and growth promotant, it is a living organism and as such requires specific conditions for establishment and long term use within a hydroponic system.
How does Trichoderma operate?
Many species of Trichoderma, if given optimal conditions, establish stable and long-lasting colonisations of root surfaces and even penetrate into the epidermis (outer layer of root tissue) and a few cells below this level (1). This intimate relationship between Trichoderma and the host root cells is what induces localized and systemic resistance responses to pathogen attack. Along with root penetration, Trichoderma produces a range of antibiotic substances, can strongly compete with other micro organisms for food, and produce enzymes that can degrade cellulose and chitin. Trichoderma also has the ability to dissolve the cell wall membranes of pathogenic fungi.
Initially Trichoderma species were only thought to have suppressive effects on a small number of plant root pathogens, however as research into the methods of this suppressive effect were studied, it was found that Trichoderma had other beneficial properties on plant growth and development. These growth enhancement effects went further than just suppression of pathogen in the root zone allowing a return to normal healthy growth. It has been found that the species Trichoderma spp. increase the uptake and concentration of a variety of nutrients (copper, phosphorus, iron, manganese and sodium) in the roots in hydroponic culture (3). This increased uptake suggests Trichoderma creates an improvement in plant active-uptake mechanisms as well as having been shown to increase root development in numerous plant species. The beneficial effects of Trichoderma on plant growth overall has been indicated to be from a combination of reducing damage, even non-visible damage, from plant pathogens, deactivation of toxic compounds in the root zone, increases in nutrient uptake, efficiency of nitrogen use and solubilization of nutrients in soil and organic matter. It is possible Trichoderma species release certain molecular elicitors of plant growth promotion in a similar way that growth promotion by certain bacteria is known to occur, however this is still an area of ongoing research and such compounds are as yet unidentified (1)