In alfalfa (lucerne), host plant resistance against the spotted alfalfa aphid is associated with__________________?
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Answer: B. High saponin in leaves
Explanation
Host plant resistance in alfalfa against spotted alfalfa aphids involves specific biochemical compounds. Elevated concentrations of saponins in leaf tissues act as natural chemical deterrents against aphid feeding. Plant secondary metabolites play a vital role in defending forage crops from herbivorous insect attacks. Spotted alfalfa aphids pierce plant vascular tissues, causing leaf yellowing, plant stunting, and yield loss. Alfalfa breeding programs select for elevated chemical defense compounds to protect crops naturally from pests. Chemical resistance mechanisms reduce dependence on synthetic insecticides in perennial forage production systems.
Dairy and livestock farmers plant pest-resistant alfalfa varieties to maintain high forage yields and quality. Agronomists monitor aphid population thresholds in alfalfa fields to determine when resistant cultivars provide adequate defense. Breeding for chemical pest resistance protects farm profitability while supporting sustainable agricultural ecosystems. Low sinigen in leaves is not the established biochemical mechanism responsible for aphid resistance in alfalfa. High DIMBOA concentration is a well-documented defense chemical found primarily in cereal crops like maize. High silica content provides mechanical defense in grasses but does not mediate aphid resistance in alfalfa.
- Subject
- Agriculture
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- Agriculture
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- Difficulty
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