Effect of Root Exudates, Glucose, Fructose, Rhizosphere, Vitamins, Thiamine, Biotin, Nucleotides, Flavones, Auxins

Effect of Root Exudates

	Effect of root exudates This is the major factor that governs the microflora of the rhizosphere. The root exudates include: Simple sugars such as glucose and fructose Di, tri and oligo saccharides All common amino acids - alanine, serine, leucine, valine, glutamic and asparitic acids. Of these, glutamine and asparagine are produced in large amounts. Vitamin¾thiamine and biotin Nucleotides Flavones and auxins Stimulators / inhibitors of particular microbes
All these root exudates have an effect on the rhizosphere microflora. Some of the root exudates like the amino acids, promote the growth of microflora of the rhizosphere. Some nitrogen fixers such as Azospirillum, Azotobacter paspali use the root exudates as the energy source for significant nitrogen fixation. Thus there is a distinct selective influence of the root system over the microbes. For example, there is a preferential stimulation of gram negative non-spore forming rods in the root region.
Root exudates contaihing toxic substances such as glycosides and hydrocyanic acid may inhibit the growth of pathogens. One of the attributes of root exudates is the possible role they play in neutralising the soil pH and altering the microclimate of the rhizosphere through liberation of water and CO2, Such changes may influence infections of roots by pathogenic fungi