general description about the allelopathy and allelochemistry with respect to agroforestry. Also, includes methods to study the allelopathy.

1. Presented by
Gajendra C.V

2. Allelopathy – Meaning and definition
• Coined by Hans molisch (1937), In Greek, Allelo and Pathos
literally Mutual suffering
• Definition: Allelopathy as any direct or indirect positive or
negative effect of one plant on the other (including the
microbes) through the release of chemicals into the
environment

3. Allelopathy perspectives and
problems
• Lack of adequate field studies
• Difficulties in determining the critical concentrations of allelo-
chemicals in soil
• Inappropriate bio-assay models
• Difficulty in establishing the role of microbes in litter
decomposition, release of allelo-chemicals and subsequent
transformation

4. Roles of microbes in modulating the interaction of allelopathic
donor-receiver species
Marsmin

5. Allelochemicals – Diversity , Nature, Mode of
Release and Significance
• In, general the chemicals responsible for the phenomenon of allelopathy is
called allelochemicals
Allelopathic classes of chemical interactions
1. Antibiotic - (Microorganism to Microorganism
2. Koline - (Plants to Plants)
3. Marsmin – (Microorganisms to Plants)
4. Phytoncide - (Plants to Microorganisms)
Based on type of donor
Plant eco-chemicals (Sapro- inhitors and phyto – inhibitors)
• The plant phenolics and Terpenoides show great chemical diversity

6. Nature
• These phytochemicals synthesized as 20
metabolites – have no direct effect function in
growth and development of plant - Defensive
adapation

7. Release of allelo-chemicals
• Lechation
• Volatilization
• Root exudates
• Decomposition of plant parts

8. Induction of allelochemical production by the plant
itself and environmental factors
Plant factors
Environmental factors
Biotic factors

9. Methods study the Allelopathy
• Plot box method
• Sandwich method
• Stair-step method
• Revised substitutive design (to descriminate the
allelopathic contribution o field condition)
• New sloped box method (allelopathy under competitive
interactions)
• A dish pack method (Volatile allelo-chemicals)

10. A New sloped box method to study allelopathic
effects of Acacia dealbata under competitive
interactions (Lorenzo et al., 2012)

11. A dish pack method - (Fang Cheng and Zhihui
Cheng, 2015)

12. Major pathway leading to production of
allelochemicals – (Wang et al., 2006)
Shikimmic acid pathway, Acid mevalanonate pathway

13. Chemical Warfare in the Plant Kingdom
Allelopathic Species Type of Chemical Affected Species
Sugar Maple Phenolics Yellow Birch, White Spruce
Hackberry Coumarins Herbs, grasses
Eucalyptus Phenolics Shrubs, herbs, grasses
Black Walnut Juglone (Quinone)
Pines, Apple, Birch, Black
Alder, Hackberry, Basswood,
Azalea,
Juniper Phenolics Grasses
Sycamore (Planetree) Coumarins Yellow Birch, herbs, grasses
Black Cherry Cyanogenic glycosides Red Maple, Red Pine
Oaks Coumarins, Herbs, grasses
Other phenolics
Sassafras Terpenoids Elm, Silver Maple, Boxelder
Balsam Poplar Green Alder
Southern Red Oak Sweetgum

14. Allelopathic problems associated with
Agriculture, Horticulture and Forestry
1) Soil sickness
2) Auto toxicity under same crop mono - cropping.
3) Increased crop- weed interference
4) Growing susceptibility of plants to disease/ pests
5) Reduced nitrification and biological nitrogen fixation
6) Reduced nutrient uptake
7) Weed seed decomposition delayed/ prevented
8) Poor success on replanting of tree crops
9) Failure of vegetative propagation (e.g. grafting, budding)
10) Suppression effect from trees

15. Recommendation
• Application of allelopathy in sustainable developmental
agriculture, especially as natural herbicide and pesticide
models

16. 2nd AFRICA - INTERNATIONAL
ALLELOPATHY CONGRESS
Topics
1. Allelopathy in sustainable and organic agriculture
2. Allelopathy in natural ecosystems
3. Allelopathy in soil sickness
4. Chemistry of alleochemicals
5. Molecular biology and genetics of allelopathy
6. Physiology and biochemistry of allelopathy
7. Allelopathy mechanisms and interactions
8. Alleopathy methodologies and modelling
Allelopathy for sustainability
November 16th -19th ,2016 Tunisia