2. ROOT EXUDATE
The various compounds that leak from growing and
expanding Sections of the roots as well as from
broken cells at exit points.
OR
The chemicals secreted into the soil by roots are
broadly referred to as root exudates
7. FUNCTIONS OF ROOT EXUDATES
Through the exudation of a wide variety of compounds
Roots may regulate the soil microbial community
Encourage beneficial symbiosis
Change the Chemical and Physical properties of soil
Inhibit the growth of competing plant species
5% to 21% of all photosynthetically fixed carbon being
transferred to the rhizosphere through root exudates
8. GROUP OF ROOT EXUDATES
Root exudates have traditionally been
grouped into :
1. Low – M r Compounds
2. High – M r Compounds
9. • Low – M r compounds such as
Amino acids
Organic acids
Sugars
Phenolics
Secondary metabolites
These compounds are believed to comprise the majority of
root exudates.
• Whereas high – M r exudates primarily include mucilage
and proteins
10. ROOT – MICROBE COMMUNICATION
• Flavonoids present in the root exudates of legumes
that activate Rhizobium meliloti genes responsible
for the nodulation process.
• Root exudates often include Phenylpropanoids and
Flavonoids
• Root exudation stimulates food – web of organisms
around roots
11. EFFECT OF ROOT EXUDATES ON NUTRIENT
AVAILABILITY IN RHIZOSPHERE
• Rhizosphere pH
• Amount and composition of root exudates
These changes are in many instances root
responses to the nutritional status of plants
Example: Zinc, Iron, and Phosphorus nutritional
status in plants.
12. FACTORS AFFECTING ROOT EXUDATES
• Plant species
• Plant age
• Temperature
• Plant nutrition
• Microorganisms
• Soil moisture
• Root damage
• Medium supporting to root
