Soil treatments that benefit plant growth and health
2012
Elad, Yigal (The Volcani Center, Bet Dagan (Israel). Agricultural Research Organization, Department of Plant Pathology and Weed Research)
The incorporation of a foreign substance or organism into soil can affect both the indigenous microflora and the chemical composition of the soil solution. These changes may affect plant reactions to signals coming from the rhizosphere and the health of the plants. The systems that will be presented involve an introduced biocontrol agent (Trichoderma harzianum T39), soil solarization and a biochar soil treatment. Soil-applied T. harzianum T39 induces resistance to foliar diseases in various plants. Biochar is a product of the pyrolysis of organic biomass. Biochar can sequester atmospheric greenhouse gases, as well as serve as an alternative to fossil fuels. Of particular importance to our research, it also has positive effects on plant growth. Biochar produced from various types of biomass induces systemic resistance against foliar diseases in tomato (the same diseases that are affected by treatment with T. harzianum T39). Analysis of the genes that are upregulated in treated plants has revealed that both T39 and biochar induce responses along both the systemic acquired resistance (SAR) pathway and the induced systemic resistance (ISR) pathway. Apart from direct interaction with plant roots, the application of either of these agents to soil leads to changes in the microbial populations in the rhizosphere of plants and causes a shift toward larger populations of the beneficial microorganisms that promote plant growth and resistance to biotic stresses. Soil solarization has a similar effect. The effects of such treatments on soil microflora are quite dramatic, implying that alternative mechanisms must contribute to the observed stimulatory effects. Microorganisms isolated from the rhizosphere of plants grown in treated soils have themselves been found to induce disease resistance.
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