1. MINERAL NUTRITION & PLANT DISEASE & PESTS Resistant phenomena : 1. Anatomy (eg. Thicker epidermal cells, higher degree of lignification)

2. 2. Physiology & Biochemistry (Production = of repelling substance & synthesis of toxins ; phytoalexins) 3. Escape from attack (not synchronize development)

3. General role of nutrient “Balanced” nutrient supply which ensures optimal plant growth is also considered optimal for plant resistance.

4. 1. Fungal disease 1.1 Principle of infection Plant exudate promote spore germination on leaf & root (air - & soil borne) Exudate depend on cellular concentration & membrane permeability

5. Sugar & amino acid K deficient Amino acid & amide N excessive Phenol accumulation N, B & Cu deff. Ca +2 inhibit function of proteolytic enzyme from fungi to dissolve middle lamella Si increase lignification of epidermal cell layer N & K effect depend on type of parasite

6. Ca 1) increase stability of membrane Ca efflux of sugar from cytoplasm apoplasm more severe infection 2) Ca - pectate & middle lamella stability & inhibit proteolytic enzyme of fungi

7. 2. Bacteria & Viral disease Bacteria Leaf spot diseases Soft rots Vascular diseases Leaf spot diseases infect through stomata & multiply in the intercellular space K & Ca deficient enhance infection

8. Soft rots infect through wounds and produce proteolytic enzyme Wound cork formation inhibit infection & increase formation when K sufficient B deficient causes cracking Ca inhibit proteolytic enzyme

9. Vascular disease plug vessel of xylem then causes “wilt” “bacterial wilt” Viral diseases need amino acid & nucleotides excessive N, P & K reduce severity of N deficient in plant due to nutrient competition between virus & plant cells

10. 3. Soilborne Fungal & Bacterial Diseases Protection Diseases Protection Chemical barriers (Polyphenol) Physical barriers (Sillicon in endodermis) pH adjustment and fungal growth Mn, Ca application NH 4 + & NO 3 - base fertilizer & pH Ammonia toxic to Fusarium Nitrite (NO 2 ) toxic to Pythium & Phytophthora The End