How to Find out Most Important Weed?

How to Find out Most Important Weed?
Importance value index (IVI) is used to determine the overall importance of each species . In calculating this index, the percentage values of the relative frequency (RF), relative density (RD) and relative abundance (RA) are summed up together. The spp. which has maximum IVI is considered most important,

Total number of individuals of a species in all quadrates
Density = -----------------------------------------------------------------
Total number of quadrates studied

Total number of quadrates in which the species occurred
Frequency (%) = ----------------------------------------------------------------------- x 100
Total number of quadrates studied

Total number of individuals of a species in all quadrates
Abundance = -----------------------------------------------------------------
Total number of quadrates in which the species occurred

Total number of individuals of the species
Relative density = ------------------------------------------------ x 100
Number of individuals of all the species


Frequency of the species
Relative frequency = ------------------------------------------------ x 100
Total frequency of all the species

abundance of a species
Relative abundance = -------------------------------------------------- x 100
Sum of abundance of all spp.

Importance Value Index (IVI)= Relative Frequency (RF) + Relative Density (RD) + Relative Abundance (RA)

Summed Dominance Ratio (SDR) = Importance value Index/3
= (RF + RD + RA)/3

Video links
1. Crop Weed Competition: A Biological Interaction - Intra and Interspecific    • Crop Weed Competition: A Biological I...  
2. Biological interactions, mutualism, Commensalism, parasitism, Neutralism, Amensalism, competition    • Explanation of Biological Interaction...  
3. Crop Weed Association, Crop Weed Interference, Crop Weed Competition and Allelopathy    • Crop Weed Association, Crop Weed Inte...  
4. Types of Weeds: Meaning and Examples    • Types of Weeds: Meaning and Examples  
5. Difference in Weeds, Off type ,Volunteer and Rogue Plants    • Difference in Weeds, Off type ,Volunt...  
6. Concept Based Questions on Weed Matching    • Concept Based Questions on Weed Matching  
7. Classification of Herbicides    • Classification of Herbicides  
8. Methods of Application of Herbicides    • Methods of Application of Herbicides  
9. Formulation and Calculation of Herbicides    • Formulation and Calculation of Herbic...  
10. Mechanism of Herbicidal Selectivity    • Mechanism of Herbicidal Selectivity  
11. Metabolism of Herbicides: A major pathway of herbicidal selectivity    • Metabolism of Herbicides: A Major Pat...  
12. Weed Control Efficiency, Weed Smother Efficiency and Weed Index: Concept and Numerical    • Weed Control Efficiency, Weed Smother...  
13. Factors Affecting Herbicide Efficacy    • Factors Affecting Herbicide Efficacy  
14. Fate of Herbicides in Soils: Decomposition and Transfer    • Fate of Herbicides in Soils: Decompos...  
15. Part 1: Persistence of Herbicides in Soils    • Part 1: Persistence of Herbicides in ...  
16. Part 2: Persistence of Herbicides in Soils: Crop management strategies to reduce it    • Part 2: Persistence of Herbicides in ...  
17. Difference in Safener, Antidote, Protectants and Adjuvants and Details of Safeners    • Difference in Safener, Antidote, Prot...  
18. Herbicide Adjuvants: Advantages, Classification and Mode of Action
   • Herbicide Adjuvants: Advantages, Clas...  
19. Types of Surfactants and Their Use in Herbicide Spray    • Types of Surfactants and Their Use in...  
20. Differences in Prevention, Eradication, Weed Control and Weed Management    • Differences in Prevention, Eradicatio...  
21. Effective Weed Management Strategy    • Effective Weed Management Strategy  
22. Reasons: How do Preventive Methods Control Weeds?    • Reasons: How do Preventive Methods Co...  
23. Limitations and Constraints in Adoption of Preventive Methods of Weed Control    • Limitations and Constraints in Adopti...  
24. Reasons: How do Cultural Methods Control weeds? Merits and Demerits    • Reasons: How do Cultural Methods Cont...  
25. Physical Methods of Weed Control    • Physical Methods of Weed Control  
26. Biological Methods of Weed Control    • Biological Methods of Weed Control  
27. Part I: Mode of Action of Herbicides   • Part I: Mode of Action of Herbicides  
28. Part II: Mode of Action of Herbicides   • Part II: Mode of Action of Herbicides  
29. Integrated weed Management    • Integrated weed Management  
30. Mechanisms of Weed Persistence    • Mechanisms of Weed Persistence  
31. Causes of Hardiness in Weeds    • Causes of Hardiness in Weeds  
32. Phytosociological Attributes of Weeds    • Phytosociological Attributes of Weeds  
33. Concept Clarity Through Multiple Choice Questions    • Concept Clarity Through Multiple Choi...  
34. How to Answer Matching Questions on Mode of Action of Herbicides    • How to Answer Matching Questions on M...  
35. Matching on Weed Control Methods    • Matching on Weed Control Methods