Assessing the efficacy of amending commercial
peat-based substrate with Neem Compost and
Vermicompost in suppressing hot pepper seedling
damping-off caused by Phytophthora capsici.
An Undergraduate Final Year Research Project – May 2018
By: Chavan Lyttle
ID#: 815007266
Supervised by Dr. Gaius Eudoxie
Overview
▪ Introduction
▪ Literature Review
▪ Materials and Methods
▪ Results and Discussion
▪ Conclusion
▪ References
INTRODUCTION
▪ Traditional plant disease management
practices have adverse environmental effects.
▪ There is therefore a need for alternative
means of managing plant diseases.
▪ Biocontrol Agents such as compost based
products are a potential solution to the
problem.
Hot Pepper (Capsicum chinense)
–Locally a domesticated
variety called Moruga Red
was developed by CARDI.
–Important crop in the
Caribbean Region(Sinha
and Petersen 2011).
–Production is significantly
affected by many plant
diseases.
Phytophthora capsici
–Oomycete fungal-like pathogen
which causes Phytophthora
Blight (damping off) in peppers
(Roberts et al. 2015; Sinha and
Petersen 2011).
–Soil borne pathogen.
Neem (Azadirachta indica)
–Fast growing evergreen tree
–Grows in poor soils and can
tolerate higher temperatures
–Produces a wide array of
secondary metabolites.
(Campos et al. 2016).
Objectives
❖ To determine the effect of neem concentration in a
compost/vermicompost treatment on suppressing seedling damping
off caused by Phytophthora capsici in hot pepper seedlings.
❖ To elucidate the possible mechanism through which suppression
against Phytophthora capsici in pepper is being mediated.
❖ To determine which type of compost (thermophilic compost or
vermicompost) is most effective at suppressing seedling dampingoff caused by Phytophthora capsici.
LITERATURE
REVIEW
Compost and Vermicompost
• An efficient means of waste management (Riquelme,
Mendez, and Smith 2016)
• Compost has a wide range of benefits when used in
agriculture. Benefits include improvement in soil
physical characteristics and enhanced suppression of
plant diseases (van Elsas and Postma 2007).
• Pathogen suppression by these products are biological in
nature and hence factors which affect microbial growth
and activity are major determinants of supressivity
(Hoitink and Boehm 1999).
Neem Substrate
• Contains a wide range of allelochemicals (Koul and Wahab
2014).
• Neem extracts contains limonoids which have been proven to be
effective biocontrol chemicals against fungal pathogens (Campos
et al 2016).
• The stability of neem compounds is affected by various
physiochemical conditions (Jarvis, Johnson and Morgan 1998).
• Very little research has been conducted on studying the use of
neem as a substrate for compost and vermicompost formulation
(Gajalakshmi and Abbasi 2004).
Phythophthora capsici
• Difficult to manage diseases caused by Phytophthora capsici due
to the wide range of propagules which can contribute to disease
development.
• Managed conventionally by chemicals with dimethomorph (eg.
Acrobat®).
• Research has shown that under in vitro conditions Phythophthora
capsici can be effectively controlled by neem extracts (Mirza et
al 2000; Qureshi and Rauf 2010).
MATERIALS
AND METHODS
Experimental Design
▪ The experiment was a completely
randomized factorial design (2×6×2×2).
which gave 48 treatment combinations
and
▪ +2 which represented vermicompost no
pre-compost (N5-NPC) inoculated and
non-inoculated treatments.
▪ Three (3) control treatments were also
included as a reference.
Table 1 showing the treatments that will be used in the experiment.
Treatments
Levels
Details
Composting System
2
1. Thermophilic Compost
2. Vermicompost
Neem leaf content in compost
formulation
6
1.
2.
3.
4.
5.
6.
Heat Application
2
1. Autoclave
2. Non-autoclave
Inoculum
2
1. Inoculated
2. Non-inoculated
0%
10%
20%
30%
40%
50%
Experimental Design Cont’d
• (5:1 v/v) mixture
Seedling and Inoculum Preparation
• Washing and planting.
• Transplanting.
• Phytophthora capsici isolates.
• Zoospore suspension
(concentration 7.5 x 103
cells/mL)
• Inoculation
Inoculum Preparation
Picture showing the mycelial growth.
Picture showing the sporangium with
zoospore.
Physiochemical Analysis and Disease Indices
Physiochemical
• pH and EC
• Bulk Density
• Water Holding Capacity
• Total Organic Matter
• Oven Dried Mass of
Shoots and Roots on noninoculated plants
Disease Severity Rating
• Area under disease
progression curves (AUDPC)
Percentage Disease
Incidence
Statistical Analysis
▪ ANOVA was done to compare the means of the control treatments to
the experimental treatments:
– Heat treatment (autoclaved or non-autoclaved),
– Neem leaf content in compost (N0, N1, N2, N3, N4,N5)
– Composting method (vermicompost and thermophilic compost).
▪ Correlation Analysis
▪ Principal Component Analysis
Statistical significance obtained at 95% confidence level (α=0.05)
RESULTS
AND DISCUSSION
7
5
a
(A)
6
(B)
4
b
b
Mean Dry Matter/ g
Mean Dry Matter/ g
5
a
4
3
3
b
2
b
2
1
1
0
0
Oven-dried Shoots
PRM
Non-autoclaved
Autoclaved
Oven-dried Roots
PRM
Non-autoclaved
Autoclaved
Figure 1 showing the mean dry matter (g) of the control (PRM), nonautoclaved and autoclaved (A) oven-dried shoots and (B) oven-dried
roots. Means with the same letter are not significantly different.
120%
120%
(B)
100%
100%
80%
80%
Disease Incidence/ %
Disease Incidence/ %
( A)
60%
60%
40%
40%
20%
20%
0%
0%
3
6
3
9
6
DAI
N0VC
N1VC
N2VC
N3VC
N4VC
N5VC
N5VC-npc
9
DAI
PRM + Ino
N0VCac
N1VCac
N2VCac
N3VCac
N5VCac
N5VC-npc ac
PRM + Ino
PRM + Ino + Fung
N4VCac
PRM + Ino + Fung
Figure 2 showing the percentage (%) disease incidence in the (A) nonautoclave and (B) autoclaved vermicompost amended growing mix at 3,
6 and 9 days after inoculation (DAI).
120%
120%
( A)
(B)
80%
80%
Disease Incidence/ %
100%
Disease Incidence/ %
100%
60%
60%
40%
40%
20%
20%
0%
0%
3
6
9
3
6
DAI
DAI
N0TC
N1TC
N2TC
N3TC
N4TC
9
N5TC
PRM + Ino
PRM + Ino + Fung
N0TCac
N1TCac
N2TCac
N3TCac
N4TCac
N5TCac
PRM + Ino
PRM + Ino + Fung
Figure 3 showing the percentage (%) disease incidence in the (A) nonautoclave and (B) autoclaved thermophilic compost amended growing
mix at 3, 6 and 9 days after inoculation (DAI).
1800
a
bc
1400
Mean Total AUDPC/ %-day
1600
ab
1200
a
ab
bc
1400
c
1000
800
600
Mean Total AUDPC/ %-day
1600
1800
1200
c
1000
800
600
400
400
200
200
0
0
Composting Method
Thermophilic Compost
Vermicompost
Ctrl+Ino
Heat Treatment
Ctrl+Ino+Fung
Figure 4 showing mean total
AUDPC for each composting
method. Means with the same letter
are not significantly different.
Autoclave
Non-autoclave
Ctrl+Ino
Ctrl+Ino+Fung
Figure 5 showing mean total
AUDPC for each method of heat
treatment. Means with the same
letter are not significantly different.
1800
a
ab
ab
ab
ab
1600
ab
ab
Mean Total AUDPC/ %-day
1400
bc
1200
c
1000
800
600
400
200
0
Treatments
N0
N3
N1
N5
N4
N2
N5-NPC
PRM+Ino
PRM+Ino+Fung
Figure 6 showing mean total AUDPC for the neem content in the
compost/vermicompost amended growing mix. Means with the same letters
are not significantly different.
Non-autoclaved inoculated thermophilic
compost treatments.
Autoclaved inoculated thermophilic
compost treatments.
Non-autoclaved inoculated vermicompost
treatments.
Autoclaved inoculated vermicompost
treatments.
Biplot (axes F1 and F2: 79.36 %)
10
Total AUDPC
8
6
EC
Water Holding Capacity
F2 (13.80 %)
4
2
N4
N4 N3
N0
N2 N3N3N5
N0
N3N2 N1
N0 N4
N2
N1 N0N2
N0
N2
N0
N4
N1
N3 N2N0
N1
N1
N0N1
N5
N2 N4
N1
N3
N2
N1
N5 N0
N1
N3 N0
N5
N4
N1
N1
N1N4 N0
N3
N5
N3
N5N3
N3N0
N5
N0
N3
N4
N5
N1
N4 N2
N1
N3
N3N1
N2N4
N5-NPC
N5-NPC
C+F
CC
C
C
N5-NPC
N5-NPC
N5-NPC
N0
N5
0
N0
N2
N1N3N5
N3 N5
N0
N2N4
N5
N4
N4 N4N1N4
N0
N5
N3N3
N2 N2 N1
N4N0 N0
N5N0 N2N5
N4 N2
N5
N2
N4
N5
N5
N2
N5
N5
N4
N2
-2
N5-NPC
N5-NPC
N5-NPC N5-NPC
N3
N1N1
C+F
C+F
C+F
N5-NPC
N0
N2
%OM
N3
pH
N4
-4
Bulk Density
-6
-8
-6
-4
-2
0
2
4
6
F1 (65.55 %)
Active variables
Active observations
Figure 7 showing Principle Component Analysis (PCA) for the
physiochemical characteristic of the compost/vermicompost and the total
AUDPC.
8
CONCLUSION,
LIMITATIONS
AND RECOMMENDATIONS
CONCLUSION
▪ The modification and possible degradation of the limonoid content
as a result of the decomposition process may have reduced the
ability of the compost and vermicompost amended growing mix to
suppress Phytophthora capsici.
▪ The possible mechanism by which suppression of Phytophthora
capsici is mediated is biological.
▪ The quality and quantity of organic matter influences the suppressive
capabilities of the compost/vermicompost amended growing mix.
Limitations and Recommendations
LIMITATION
RECOMENDATION
▪ Experimental design did not
allow for the statistical analysis
of the mechanism mediating
suppression.
▪ Redesign an experiment
specifically to study the
mechanism by which
suppression is mediated.
▪ Age compost was utilized and
hence the organic matter
quality was unknown.
▪ Conduct analysis which would
provide deeper insight into the
mechanism of suppression
such as FDA.
REFERENCES
▪
Ahmed, S. 2005. “Neem in Sociocultural Life in South Asia.” The Neem Tree: Source of Unique Natural
Products for Integrated Pest Management, Medicine, Industry and Other Purposes, 579–84.
doi:10.1002/3527603980.ch7.
▪
Campos, Estefânia V. R., Jhones L. de Oliveira, Mônica Pascoli, Renata de Lima, and Leonardo F. Fraceto. 2016.
“Neem Oil and Crop Protection: From Now to the Future.” Frontiers in Plant Science 7 (October): 1–8.
doi:10.3389/fpls.2016.01494.
▪
Gajalakshmi, S., and S. a. Abbasi. 2004. “Neem Leaves as a Source of Fertilizer-Cum-Pesticide Vermicompost.”
Bioresource Technology 92: 291–96. doi:10.1016/j.biortech.2003.09.012.
▪
Ketkar, A.Y., C.M. Ketkar, M Jacobson, M.S. Ketkar, and H. Schmutterer. 1995. Various Uses of Neem Products.
The Neem Tree Azadirachta Indica A. Juss. and Other Meliaceous Plants. doi:10.1002/3527603980.ch6.
▪
Kraus, W. 1995. “Biologically Active Ingredients.” In The Neem Tree Azadirachta Indica A. Juss. and Other
Meliaceous Plants, 35–74.
▪
Mirza, Javed Iqbal, Shazia Hameed, Iftikhar Ahmad, Najma Ayub, and R.H.C. Strang. 2000. “In Vitro Antifungal
Activity of Neem Products Against Phytophthora Infestans.” Pakistan Journal of Biological Sciences 3 (5).
Capricorn Publications: 824–28. http://www.pjbs.org.
REFERENCES CONT’D
▪
Pathma, Jayakumar, and Natarajan Sakthivel. 2012. “Microbial Diversity of Vermicompost Bacteria That
Exhibit Useful Agricultural Traits and Waste Management Potential.” SpringerPlus 1 (1). Springer: 26.
doi:10.1186/2193-1801-1-26.
▪
Qureshi, Rahmatullah, and C a Rauf. 2010. “In Vitro Antifungal Activity of Selected Medicinal Plant
Diffusates Against Alternaria Solani , Rhizoctonia Solani and Macrophomina Phaseolina” 42 (4): 2911–
19.
▪
Roberts, Pamela D, Amanda J Gevens, Robert J Mcgovern, and Thomas A Kucharek. 2015. “Vegetable
Diseases Caused by Phytophthora Capsici in Florida.” Plant Pathology Department, UF/IFAS Extension.
http://edis.ifas.ufl.edu/pdffiles/VH/VH04500.pdf.
▪
Sinha, Anil, and Joan Petersen. 2011. Caribbean Hot Pepper Production and Post Harvest Manual.
Trinidad and Tobago: Food and Agriculture Organization of the United Nations (FAO); Caribbean
Agricultural Reasearch and Development Institute (CARDI). http://www.cardi.org/wpcontent/uploads/downloads/2013/02/Cbbean-hot-pepper-production-post-harvest-manual.pdf.
THE END.
THANK YOU FOR LISTENING
ANY QUESTIONS?