2. ROLE OF NPK IN plant
fungal DISEASE
RESISTENCE
PRESENTER:
SHILPA V MALAGHAN
Jr. MSc ( agri).
Dept ; GPB
AC, Raichur
UAS, Raichur.

3. CONTENTS
• Introduction
• Mode of action of nutrients in HPR
• Role of N
• Role of Ca
• Role of P
• ROLE OF K
• Conclusion
• Discussion

4. INTRODUCTION

5. How can mineral nutrition prevent
plant disease?
Mineral nutrition can affect two primary
resistance mechanisms:
• Physical resistance
(e.g.cuticle layer, thickness of cell walls).
• Chemical resistance
e.g.nitrogen compounds (including alkaloids, cyanogenic
glycosides and glucosinolates)
terpenoids (rishitin, pisatin, gossypol) and phenolics.

8. • High nitrogen level in plant will produces the food for the pathogen
• Excess nitrogen delays maturity of plant tissues and therefore
increases the risk of disease infection and development
• Excess nitrogen promotes thinner and weaker cell walls
• The addition of nitrogen to the soil in different forms can also alter
the activity of soil micro flora

9. • Increased nitrogen improves microclimate for pathogen
• Facultative parasitic fungi like fussarium are actually suppressed
by higher N levels
• Unbalanced N :K ratio affects both yield and disease resistance.
• High N applications can also effect the production of
phenolic compounds needed for lignin
• Increased Nitrogen level in the soil is congenial for , Ca, Si,
K and Zn deficiency in the plants

10. Tentative Summary of the Effect of
Nitrogen Levels on the Severity of
Diseases Caused by Parasites
Nitrogen Level
Pathogen and Disease Low High
Obligate parasites
Puccinia spp. (rusts) + +++
Erysiphe graminis (powdery mildew) + +++
Facultative parasites
Alternaria spp. (leaf spots) +++ +
Fusarium oxysporum (wilts and rots) +++ +
Xanthormonas spp. (spots and wilts) +++ +

14. Ca

15. The Cell – In Relation to Disease

16. • A. The cell wall is the combination of the two “mats of fibre” which
are “glued” together by a “polymerized gel”
• B. Middle lamella – The “polymerized gel” is like glue that binds the
two layers together and forms the cell wall
• C. Plasmodesmata – important in the translocation of nutrients and
cellular material
• D. Plasma membrane – The 2nd “line of defence” which keeps the
disease “food” (simple amino acids & sugars) in the cell. This is also
a very important part of natural disease resistance

17. Ultra Structure of Cell Wall.

18. Calcium protects plants in three
important ways
1. Calcium maintains the stability of Plasma
membrane

19. PHYSICAL RESISTANCE

20. Continued……
2. Calcium is main component of the enzyme:
Calcium polygalacturonates, which are required in
the middle lamella for cell wall stability
3. “Hypersensitive” response to disease (SAR or ISR)

21. P

22. • Phosphorus is important in early and strong root, stalk and
stem development
• Phosphorus is a vital component of Neuclic acid; the genetic
"memory unit" of all living things
• P as “Energy unit”
• P as a “catalyst” in the biochemical reactions of plants
• P produces more uniform and earlier crop maturity
• It helps in withstanding the stress condition and there by
increases the resistance

23. K

24. How K suppresses plant disease
• Converts simpler molecule to complex and rigid molecules.
• Potassium in proper quantity makes the plants to absorb Silica
in the soil
• Decreased cell permeability
• Decreased susceptibility of tissue to maceration and
penetration. because Potassium has role in the proper
thickening of cell walls
• Promotes the healing of wounds in plants, all of which
increases the disease resistance

25. • Makes the plant to tolarate stress condition.
• High K:Ca might leads to Ca deficiency and thus it
decreases the resistance.
• It helps to maintain cat ion concentration of cell.

26. Tentative Summary of the Effect of Potassium
Levels on the Severity of Diseases Caused by
Parasites.
Potassium Level
Pathogen and Disease Low High
Obligate parasites
Puccinia spp. (rusts) ++++ +
Erysiphe graminis (powdery mildew) ++++ +
Facultative parasites
Alternaria spp. (leaf spots) ++++ +
Fusarium oxysporum (wilts and rots) ++++ +
Xanthormonas spp. (spots and wilts) ++++ +
Based on Kiraly (1976) and Perrenoud (1977). 1998. “Mineral
Nutrition of Higher Plants. 2nd ed. Horst Marschner.” p. 443.

27. Relationship Between Cat ion Content and
Severity of Infection with Botrytis cinerea Pars.
In Lettuce
Cat ion content (mg/g dry wt.) Infection1
with
K Ca Mg Botrytis
14.4 10.6 3.2 4
23.8 5.4 4.1 7
34.2 2.2 4.7 13
48.9 1.8 4.2 15
1 Infection index: 0-5 slight infection
6-10 moderate infection
11-15 severe infection
Based on Krauss (1971). 1998. “Mineral Nutrition of Higher Plants.” 2nd ed. Horst
Marschner. P.447

28. THE EFFECT OF POTASSIUM ON ALTERNARIA
LEAF SPOT, DEFOLIATION, and COTTON
LINT YIELD

29. Potassium and soybean disease
incidence on sandy soil

33. ?