Keywords:
Meloidogyne incognita: Root-knot nematode causing galls on plant roots.
Tobacco plant: Nicotiana tabacum, cultivated for leaves used in tobacco products.
Root infection: Pathogen entry site for many nematodes.
Gall formation: Swelling on roots due to nematode feeding.
Plant-parasitic nematodes: Nematodes feeding on living plant tissue causing disease.
Symptoms: Wilting, stunted growth, yellowing leaves due to root damage.
Crop management: Methods to control nematode infestations.
Host specificity: Tendency of pathogens to infect specific plants.
Pathogen lifecycle: Stages of nematode development in host plant.
Agricultural impact: Effect of nematodes on yield and quality of crops.
Soil treatment: Measures to reduce nematode population in fields.
Chapter: Plant Pathology
Topic: Nematode Diseases of Crop Plants
Subtopic: Root-Knot Nematodes
Lead Question - 2016 (Phase 1): Which part of the tobacco plant is infected by Meloidogyne incognita ?
(1) Flower
(2) Leaf
(3) Stem
(4) Root
Answer: 4
Explanation: Meloidogyne incognita, a root-knot nematode, specifically infects the roots of the tobacco plant. It forms characteristic galls, disrupting water and nutrient uptake, causing stunted growth and yellowing of leaves. Leaves, flowers, and stems remain uninfected directly.
1. Single Correct Answer MCQ: Which of the following is a symptom of root-knot nematode infection in tobacco?
(A) Leaf spots
(B) Root galls
(C) Stem lesions
(D) Flower drop
Answer: B
Explanation: Root galls are formed when Meloidogyne incognita invades roots, causing swelling, nutrient deficiency, stunted growth, and yellowing of leaves. Other parts remain unaffected directly.
2. Single Correct Answer MCQ: Meloidogyne incognita belongs to which group of organisms?
(A) Bacteria
(B) Fungi
(C) Nematodes
(D) Viruses
Answer: C
Explanation: Meloidogyne incognita is a plant-parasitic nematode, causing root-knot disease. It is neither bacterial, fungal, nor viral.
3. Single Correct Answer MCQ: The primary damage caused by Meloidogyne incognita is:
(A) Leaf necrosis
(B) Flower abortion
(C) Impaired nutrient and water uptake
(D) Stem canker
Answer: C
Explanation: Root infection by nematodes forms galls, reducing root function, which impairs water and nutrient absorption, leading to stunted plants and reduced yield.
4. Single Correct Answer MCQ: Which stage of Meloidogyne incognita infects the tobacco roots?
(A) Egg
(B) Juvenile stage 2 (J2)
(C) Adult male
(D) Adult female
Answer: B
Explanation: The second-stage juvenile (J2) is the infective stage that penetrates plant roots and initiates gall formation.
5. Single Correct Answer MCQ: A key management strategy for root-knot nematodes is:
(A) Fungicide application
(B) Soil solarization
(C) Foliar fertilizer spray
(D) Pruning leaves
Answer: B
Explanation: Soil solarization reduces nematode population in soil by using high temperatures. Fungicides do not affect nematodes, and foliar sprays or pruning are ineffective for root infestation.
6. Single Correct Answer MCQ: Root-knot nematodes primarily affect:
(A) Monocots only
(B) Dicots only
(C) Both monocots and dicots
(D) Gymnosperms only
Answer: C
Explanation: Meloidogyne incognita can infect a wide range of host plants including both monocot and dicot crops, though host susceptibility varies.
7. Assertion-Reason MCQ:
Assertion (A): Root galls reduce nutrient absorption.
Reason (R): Meloidogyne incognita forms feeding sites inside roots.
(A) Both A and R are true, R is correct explanation of A
(B) Both A and R are true, R is NOT correct explanation of A
(C) A is true, R is false
(D) A is false, R is true
Answer: A
Explanation: Root galls formed by nematode feeding disrupt vascular tissues, reducing nutrient and water uptake, thus stunting plant growth. The reason correctly explains the assertion.
8. Matching Type MCQ: Match plant part with pathogen effect:
1. Root A. Gall formation
2. Stem B. Lesion
3. Leaf C. Spots
4. Flower D. Wilting
(A) 1-A, 2-B, 3-C, 4-D
(B) 1-A, 2-C, 3-B, 4-D
(C) 1-D, 2-B, 3-C, 4-A
(D) 1-B, 2-A, 3-C, 4-D
Answer: A
Explanation: Root-knot nematodes form galls on roots, stem and leaf diseases produce lesions or spots, and flower wilting can be secondary. This correctly matches pathogen effects to plant parts.
9. Fill in the Blanks: The infective stage of Meloidogyne incognita penetrates ________ and forms ________.
(A) Roots; galls
(B) Leaves; lesions
(C) Stem; cankers
(D) Flowers; spots
Answer: A
Explanation: The J2 juvenile stage penetrates roots, induces gall formation, impairs nutrient absorption, and indirectly causes above-ground symptoms.
10. Choose the Correct Statements:
(A) Meloidogyne incognita infects roots.
(B) It forms galls.
(C) Leaf infection is common.
(D) J2 is infective stage.
(1) A, B, D
(2) A, C, D
(3) B, C
(4) All are correct
Answer: 1
Explanation: Meloidogyne incognita infects roots, forming galls. The J2 juvenile is the infective stage. Leaf infection is not typical.