CPRT41 Principles of Crop Protection: Weed Science
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Questions and Answers

What is the scientific name for Corn?

  • Ipomoea triloba
  • Lantana camara
  • Zea mays (correct)
  • Imperata cylindrica

    • Which of the following is NOT a characteristic of weeds?

  • They can adapt to adverse environmental conditions
  • They persist and resist control measures
  • They have slow vegetative growth (correct)
  • They produce seeds efficiently

    • What are common weeds characterized by?

  • Expensive management
  • Difficult control
  • Ease of control (correct)
  • High destructiveness

    • Which plant is known as Makahiya?

    <p>Mimosa pudica</p> Signup and view all the answers

    What type of effects do weeds have according to their categorization?

    <p>Both harmful and beneficial effects</p> Signup and view all the answers

    Which of the following is an example of an escape plant?

    <p>Lantana camara</p> Signup and view all the answers

    Which common weed is also known as Cogon grass?

    <p>Imperata cylindrica</p> Signup and view all the answers

    What is one significant harmful effect of weeds?

    <p>Reducing yield quantity and quality</p> Signup and view all the answers

    What is the primary focus of weed science?

    <p>Control of weeds and their impact on crops</p> Signup and view all the answers

    Which characteristic allows weeds to outcompete crops effectively?

    <p>Producing a lot of seeds that can survive in the soil</p> Signup and view all the answers

    What is a primary characteristic of grasses based on their gross morphology?

    <p>Their stems are succulent with well-defined nodes and internodes.</p> Signup and view all the answers

    What defines a weed in the context of crop production?

    <p>A plant that grows where it is not wanted</p> Signup and view all the answers

    What is a noxious weed?

    <p>A competitive weed that reduces yields even at low populations</p> Signup and view all the answers

    In which family do sedges belong?

    <p>Family Cyperaceae</p> Signup and view all the answers

    How do broadleaves primarily differ from grasses and sedges?

    <p>They have fully expanded leaves with netted venation.</p> Signup and view all the answers

    How does the herbicide 2,4-D function in relation to weeds?

    <p>It acts as a growth regulator when used at low concentrations</p> Signup and view all the answers

    Which statement describes 'volunteer crops'?

    <p>Plants that grow without being deliberately seeded</p> Signup and view all the answers

    What is a common feature of the root systems found in grasses?

    <p>They are fibrous with shallow penetration.</p> Signup and view all the answers

    Which process involves the transfer of male gametes to female ovules in flowering plants?

    <p>Pollination</p> Signup and view all the answers

    Why are weeds considered undesirable in crop production?

    <p>They compete for resources like light, water, and nutrients</p> Signup and view all the answers

    Which of the following is NOT a characteristic of weeds?

    <p>They typically grow in harmony with cultivated plants</p> Signup and view all the answers

    What distinguishes sedge stems from those of grasses?

    <p>Sedge stems are triangular in shape.</p> Signup and view all the answers

    What type of root system do most broadleaved plants exhibit?

    <p>A combination of fibrous and tap root systems.</p> Signup and view all the answers

    What is a reproductive characteristic of weeds as mentioned in the content?

    <p>They can produce thousands of seeds per plant during the vegetative phase.</p> Signup and view all the answers

    What is the main characteristic of asexual reproduction in plants?

    <p>A new plant develops from a vegetative organ.</p> Signup and view all the answers

    Which of the following is NOT a modification commonly associated with vegetative reproduction?

    <p>Seeds</p> Signup and view all the answers

    What role do adaptive structures play in dispersal?

    <p>They determine how and where seeds move.</p> Signup and view all the answers

    Which dispersal agent is characterized by seeds that can remain viable after passing through an animal's digestive system?

    <p>Animals</p> Signup and view all the answers

    How does wind contribute to seed dispersal?

    <p>By dispersing lightweight seeds with wings or hair.</p> Signup and view all the answers

    Which of the following is a key determinant for weed dispersal?

    <p>Seed structure</p> Signup and view all the answers

    What is meant by a 'dispersal unit' in the context of plant dispersal?

    <p>The structure including a seed and its accessory parts.</p> Signup and view all the answers

    Why is man considered one of the best agents of seed dispersal?

    <p>Humans can disperse seeds both consciously and unconsciously.</p> Signup and view all the answers

    What is referred to as the Critical Period of Competition?

    <p>The duration when crops are most sensitive to weed competition.</p> Signup and view all the answers

    Which factor significantly influences the competing ability of a crop against weeds?

    <p>Weed species present</p> Signup and view all the answers

    What does the Critical Threshold Level indicate?

    <p>The threshold of weed density causing yield reduction.</p> Signup and view all the answers

    How do allelochemicals affect plants?

    <p>They interfere with mineral ion uptake and growth processes.</p> Signup and view all the answers

    Why is timing important in the application of fertilizers concerning weed control?

    <p>Incorrect timing can either suppress or exacerbate weed growth.</p> Signup and view all the answers

    Which statement about weed control methods is true?

    <p>A combination of methods is often required for effective weed management.</p> Signup and view all the answers

    What role does soil fertility play in the competition between crops and weeds?

    <p>Proper soil fertility can either suppress or encourage weed growth.</p> Signup and view all the answers

    What is a major consequence of high weed intensity in a crop field?

    <p>It creates biological stress that can harm crop performance.</p> Signup and view all the answers

    Study Notes

    Weed Science Overview

    • Focuses on the study and management of weeds in crop protection.
    • Evolved from plant physiology, notably with the discovery of the herbicide 2,4-D, which functions as a growth regulator at low concentrations.

    Definition of Weeds

    • Classified as plants growing in undesired places, competing with cultivated plants.
    • Weeds reduce crop yield by competing for land, light, water, and nutrients.
    • Their classification is based on subjective human perception, often carrying a negative connotation.

    Characteristics of Weeds

    • Weeds are adept at outcompeting crops due to several traits:
      • High seed production with long-term soil viability.
      • Rapid root spread and growth.
      • Adaptability to disturbed environments.

    Noxious Weeds

    • Highly competitive and harmful even at low populations, affecting crop yields.
    • Examples include Chromolaena odorata (Hagonoy or Devil weed).

    Volunteer Crops

    • Plants that grow independently without intentional cultivation.
    • Example: Zea mays (Maiz or Corn).

    Escape Plants

    • Non-native ornamental plants that establish wild populations through dispersal.
    • Example: Lantana camara (Kanding-kanding).

    Common Weeds

    • Frequently found in fields, typically easier to control and less destructive.
    • Examples:
      • Imperata cylindrica (Cogon grass)
      • Ipomoea triloba (Morning glory)
      • Mimosa pudica (Makahiya)
      • Cyperus rotundus (Purple nutsedge)

    Unique Characteristics of Weeds

    • Rapid vegetative growth and significant root production.
    • Efficient early seed production and adaptation to adverse conditions.
    • High damage potential, even in low densities.
    • Resistance to control measures.

    Harmful Effects of Weeds

    • Decrease both the quantity and quality of crop yields.
    • Increase production costs in agriculture.

    Classification Based on Morphology

    • Grasses: Family Gramineae (Poaceae), characterized by succulent stems and fibrous roots, e.g., Eleusine indica, Echinochloa glabrescens.
    • Sedges: Family Cyperaceae, with triangular stems and fibrous roots, often creeping.
    • Broadleaves: Diverse families, identified by expanded leaves with netted venation and tap or fibrous roots, e.g., Centella asiatica, Euphorbia hirta.

    Reproduction and Establishment

    • Two primary plant propagation methods:
      • Sexual (Seeds): Involves gamete production, pollination, and fertilization.
      • Asexual (Vegetative): Growth from organs like stems or rhizomes; can yield many new plants.

    Seed Dispersal Mechanisms

    • Wind: Seeds with adaptable structures, such as dandelion seeds.
    • Water: Seeds that float, common in aquatic environments.
    • Animals: Seeds that pass through the digestive systems of animals and remain viable.
    • Human activity: Deliberate or accidental dispersal of seeds.

    Competition in Cropping

    • Critical Period of Competition: Timeframe in which crops are most sensitive to weed presence, critical for maintaining yield.
    • Critical Threshold Level: Density of weeds that, if exceeded, results in significant yield loss.

    Factors Affecting Crop Competition

    • Timing of weed germination relative to crops.
    • Intensity and specific species of weeds present.
    • Soil fertility and nutrient management.
    • Allelopathy: Chemical interactions between different plant species impacting growth.

    Allelochemicals

    • Produced by plants that affect germination and growth of others through biochemical interference in various physiological processes, including:
      • Cell elongation, photosynthesis, respiration, and nutrient uptake.

    Management of Weed Populations

    • Effective weed control requires diverse strategies tailored to specific weed species.

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    Related Documents

    Weed Science Component PDF

    Description

    Explore the essentials of weed science within crop protection in this engaging quiz. Learn about the impact of weeds, their control mechanisms, and the significance of herbicides like 2,4-D. This quiz is designed for students studying CPRT41 principles and is a vital component of effective agricultural practices.

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