Allelopathy

Allelopathy is the chemical inhibition of one plant (or other organism) by another, due to the release into the environment of substances acting as germination or growth inhibitors.

1. ALLELOPATHY
Department of Agronomy BZU Multan
Presented By:
Malik Ghulam Asghar

2. Outline
1)Background
2)Allelopathy
3)Allelopathic interactions
4)Allelopathic Chemicals
5)Mode of Action of Allelochemicals
6)Effects of Allelochemicals
7)Types of Allelopathy
8)Ways of releasing Allelochemicals
9)Factors affecting the Allelopathy
10)Allelopathy and Competition
11)Allelopathy and weeds management

3. Background
Harmful
effects of
Herbicides

4. ALLELOPATHY
Definition
Greek words
allelonwhich means "of each other“
pathos which means "to suffer".
“Allelopathy refers chemicals
released into the environment
where it affects the development
and growth of neighboring plants”

5. Forms of Allelopathic Interactions
Forms of Allelopathy
Weed on
Crop
Weed on
Weed
Crop on weed

6. Allelopathic Interaction
1)WeedonCrop
Junglipallakaffect the wheat plant growth and development
Inhibits

7. Allelopathic Interaction
2)WeedonWeed
Imperetacylindrica(Cogongrass)inhibitstheemergenceandgrowth
ofanannualbroadleafweedi.e.Borreriahispada(Buttonweed)by
exudationinhibitorysubstancesthroughrhizomes.
Inhibits

8. Allelopathic Interaction
3) Crop on Weed
Oat,pea,wheatsuppressthegrowthofChenopodiumalbum
(Lamsquarter)
Inhibits

9. Allelopathic effects of crops on weeds
Crop Weed sp. Source of inhibitors
Maize Chenopodiumalbum,
Amaranthusretroflexus
Roots
Sorghum Abutylontheophrasti,
Amaranthushybridus
Shoots and foliages
Rye Digitariasanguinalis,
Ambrosia artimisifolia
Shoots and foliages

10. Allelopathic Chemicals
Phenolic acid
Coumarins
Terpinoids
Flavinoids
Scopulatens

11. Mode of Action of Allelochemicals

12. Extract preparation of Allelochemicals
Washing
Drying
70 ˚c
Chopping
Grinding
Mixing
1:20
Extract

13. Types of allelopathy
1. True Allelopathy
The true allelopathy is the release of substances that are toxic in the form
in which they are produced in the plant.
2. Functional Allelopathy
Functional allelopathy is the release of substances that are toxic or a
result of transformation by micro-organism .

14. Ways of releasing Allelochemicals
Allelopathic chemicals are released from
the plants as:
Vapour –from root and leaf (through
stomata)
Foliar
Root
Breakdown/ decomposition product of
dead plant parts
Seed extract

15. Factors affecting Allelopathic effect
Allelopathic effects might also depend on a number of other factors that might be
important in any given situation:
Varieties
Specificity
Auto-toxicity
Crop on crop effects
Environmental factors

16. Advantages of Allelopathy
1)Limit competition for space,
light, nutrients, water
2)Autotoxity (Chemical produced
inhibits germination of it's own
seeds)
3)Allelopathic Weed Suppression
Through the Use of Cover Crops

17. Allelopathy and Weed Management
Allelopathicextractshavebeensuccessfully
usedfororganicweedmanagement.
Allelochemicalsarediverseinnatureand
structureandthuslackcommonmodeof
action.
ThisphytotoxicactivityofAllelochemicalsis
responsibleforgrowthsuppressionofweeds.

18. Allelopathy and competition
Plantswillcompeteforsunlight,water
andnutrients.
Allelopathicplantspreventotherplants
fromusingtheavailableresourcesand
thusinfluencetheevolutionand
distributionofotherspecies.

19. Management of Plant Allelopathy
Arrangement of Cropping Systems
Cropallelopathycanbeeffectivelyusedto
controlweedsinthefield.
Byintercroppingthosefieldcropswhichcan
suppressweedsofnextcrops

20. Management of Plant Allelopathy
StrawMulching
Allelopathicapplications,suchasstraw
mulching,providesustainableweed
management
Theallelochemicalsfromdecomposed
strawcansuppressweedgrowthin
farmlands,andreducetheincidenceof
pestsanddiseases.

21. Thank you !