With reference to the depth of sowing, consider the following statements: 1. Seeds must be sown at appropriate depths to ensure good yield. 2. Seeds sown on the surface are naturally protected from birds by sunlight. 3. Seeds sown very deep germinate faster due to higher soil pressure. Which of the statements given above is/are correct?

The correct option is (a). Explanation Sowing depth is a critical agronomic factor that influences seed germination, seedling emergence, and crop establishment. The ideal depth balances the need for soil moisture and protection against the energy required for the embryonic shoot to reach the soil surface. Statement-wise Analysis: - Statement 1 is Correct: Seeds must be sown at an appropriate depth to ensure they have access to sufficient soil moisture and are protected from external hazards. Proper depth ensures high germination rates and uniform stand establishment, which are prerequisites for a good yield. - Statement 2 is Incorrect: Seeds sown on the surface are not protected; rather, they are highly vulnerable to being eaten by birds and insects. Sunlight does not act as a deterrent to birds. Additionally, surface seeds are prone to desiccation (drying out) due to direct exposure to heat and wind. - Statement 3 is Incorrect: Sowing seeds too deep generally retards or prevents germination. Deeply sown seeds may experience hypoxia (lack of oxygen) and the seedling may exhaust its stored food reserves before the shoot can break through the soil surface. Higher soil pressure acts as a physical barrier to emergence, delaying rather than accelerating the process. Key Takeaway: The depth of sowing is determined primarily by seed size and soil moisture; sowing too shallow risks predation and desiccation, while sowing too deep risks energy exhaustion and poor aeration.

With reference to the depth of sowing, consider th... - NCERT Class 8 Science MCQ

Solution

The correct option is (a).

Explanation

Sowing depth is a critical agronomic factor that influences seed germination, seedling emergence, and crop establishment. The ideal depth balances the need for soil moisture and protection against the energy required for the embryonic shoot to reach the soil surface.

Statement-wise Analysis:

Statement 1 is Correct: Seeds must be sown at an appropriate depth to ensure they have access to sufficient soil moisture and are protected from external hazards. Proper depth ensures high germination rates and uniform stand establishment, which are prerequisites for a good yield.
Statement 2 is Incorrect: Seeds sown on the surface are not protected; rather, they are highly vulnerable to being eaten by birds and insects. Sunlight does not act as a deterrent to birds. Additionally, surface seeds are prone to desiccation (drying out) due to direct exposure to heat and wind.
Statement 3 is Incorrect: Sowing seeds too deep generally retards or prevents germination. Deeply sown seeds may experience hypoxia (lack of oxygen) and the seedling may exhaust its stored food reserves before the shoot can break through the soil surface. Higher soil pressure acts as a physical barrier to emergence, delaying rather than accelerating the process.

Key Takeaway: The depth of sowing is determined primarily by seed size and soil moisture; sowing too shallow risks predation and desiccation, while sowing too deep risks energy exhaustion and poor aeration.

NCERT Class 8 Science — Chapter 1: Crop production and management

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