Explanation

• Oligogenic resistance refers to vertical resistance in plants, controlled by one or a few major genes.
• It provides specific resistance against particular strains of pathogens.

Additional information:

• Vertical resistance can be easily overcome by pathogen evolution.
• Commonly used in breeding for disease-resistant crop varieties.

Last verified on 20-01-2026

Explanation

• Parthenium hysterophorus is an invasive weed that causes severe damage to agriculture, livestock, and human health.
• Its global economic loss is estimated at about 36 billion dollars.

Additional information:

• Commonly known as Congress grass.
• It spreads rapidly due to high seed production and adaptability.

Last verified on 20-01-2026

Explanation

• Reducing post-harvest losses can significantly increase the overall food supply.
• Studies show that food availability can be increased by about 10–20% through better storage, transport, and processing.

Additional information:

Major causes of post-harvest losses:

• Poor storage facilities
• Inadequate transportation
• Improper handling
• Pest infestation
• Lack of cold chain systems

Last verified on 20-01-2026

Explanation

• A dormant seed is alive and viable but does not germinate even under favorable conditions.
• Dormancy is a protective mechanism to survive unfavorable environments.

Additional information:

• Dormancy can be broken by scarification, stratification, or temperature treatment.
• Dormant seeds ensure plant survival across seasons.

Last verified on 20-01-2026

Explanation

• Seeds with a short storage period lose their viability quickly.
• Such seeds can generally be stored for about 1–2 months under normal conditions.

Additional information:

Storage life of seeds:

• Short-lived seeds – 1–2 months
• Medium-lived seeds – 3–8 months
• Long-lived seeds – 9–12 months or more
• Onion seeds – short storage life
• Lettuce seeds – short storage life

Last verified on 19-02-2026

Explanation

• Residual phenolics are chemical compounds in plants or soil that remain active for a period of 2 to 5 months.
• They help in protecting plants against pests and diseases.

Additional information:

Duration of residual effects in common substances:

• Phenolics – 2 to 5 months
• Organophosphates – 1 to 2 months
• Carbamates – 1 month
• Pyrethroids – 3 months
• Neonicotinoids – 4 to 5 months

Last verified on 19-01-2026

Explanation

• Unisexual flowers have either male (staminate) or female (pistillate) reproductive organs, but not both.
• They are important in plants that rely on cross-pollination.

Additional information:

Examples of unisexual plants:

• Papaya (Carica papaya) – male and female flowers separate
• Cucumber (Cucumis sativus) – male and female flowers
• Maize (Zea mays) – tassel (male) & cob (female)
• Date palm – male and female trees
• Ginkgo – separate male and female trees

Last verified on 19-01-2026

Explanation

• Globally, about 30% of food produced is lost or wasted before reaching consumers.
• This includes losses during harvesting, storage, transportation, and processing.

Additional information:

Food loss by stage:

• Harvesting – 10%
• Post-harvest handling – 5%
• Processing – 5%
• Distribution – 5%
• Retail & households – 5%

Last verified on 19-01-2026

Explanation

• Pakistan’s forest area is decreasing over the years due to deforestation, urbanization, and overgrazing.
• Forests cover about 5% of Pakistan’s total land area.

Additional information:

• Major forests: Himalayan, Indus plain, and mangrove forests.
• Government programs like tree plantations and protected areas aim to slow down deforestation.

Explanation

Major sucking pests of cotton include:

• Whitefly – Causes leaf curling and transmits cotton leaf curl virus.
• Jassid (Leafhopper) – Sucks sap from leaves, causing yellowing.
• Aphid – Sucks plant sap and spreads viral diseases.

Additional information:

• Sucking pests reduce plant vigor and yield.
• Control methods: insecticides, biological control, and resistant varieties.

Last verified on 19-01-2026