Which of the following insects is the carrier of grassy stunt pathogenic virus? (IFFCO 2022)

✅Explanation:
The permanent wilting point (PWP) is the minimum soil moisture level at which a plant wilts and cannot recover even when placed in a humid atmosphere. Sunflower is commonly used as an indicator plant for determining PWP.

• Here's why sunflower is suitable for this purpose:
-Sensitivity to water stress: Sunflowers show clear wilting symptoms when they reach the PWP.
-Deep root system: They have roots that can explore a large volume of soil, giving a good indication of the overall moisture status.
-Rapid growth: Sunflowers grow relatively quickly, allowing for faster determination of PWP.
-Easy to observe: Their large leaves make wilting symptoms easily visible.

🔑Key Points:
 Permanent Wilting Point (PWP)
-In Permanent Wilting Point (PWP) plants can be no longer obtains enough moisture to meet their requirements and remained wilted until water is added into the soil.
– It is a soil characteristic.
-It is the lower limit of available water to plant.
-Soil moisture tension at PWP is about -15 bars or 15 atmospheres.