ICAR AIEEA PG 2024 - Plant Sciences

विस्तृत व्याख्या:

Determinants of Seed Certification Isolation Distance (पृथक्करण दूरी के निर्धारक कारक):

• In certified seed production, spatial isolation distance is maintained to prevent physical contamination and genetic contamination from foreign cross-pollen of other varieties or wild relatives.
• The critical factor governing cross-pollination distance is the mode of pollination and nature of pollinating agents (परागणकारी कारक):
• Anemophilous (wind-pollinated) crops (e.g., maize, pearl millet): Pollen grains travel hundreds of meters on wind currents, necessitating large isolation distances (400–1,000 m).
• Entomophilous (insect-pollinated) crops (e.g., mustard, sunflower, cucurbits): Isolation distance is determined by the foraging range and flight behavior of pollinating insects (honeybees, bumblebees).
• Plant height, germination rate, and soil fertility do not govern cross-pollen transmission.

Correct Answer: Option 4 (Type of pollinating agent).

विस्तृत व्याख्या:

ICAR-NBPGR (राष्ट्रीय पादप आनुवंशिक संसाधन ब्यूरो):

• Established in 1976 and headquartered in New Delhi, the National Bureau of Plant Genetic Resources (ICAR-NBPGR) is the nodal national agency in India mandated with:

• Exploration and germplasm collection across agro-ecological zones.
• Plant quarantine and introduction of exotic plant genetic resources.
• Characterization, evaluation, and documentation of crop accessions.
• Long-term ex-situ conservation in the National Gene Bank (NGB) at $-18^\circ\text{C}$ / cryopreservation in liquid nitrogen (second largest genebank in the world).
  • PPV&FRA grants plant breeders' rights and registration under the PPV&FR Act 2001, but is not the conservation repository.

विस्तृत व्याख्या:

Hardy-Weinberg Law of Population Genetics (हार्डी-वीनबर्ग समीकरण):

• In a large, randomly mating population free from selection, mutation, and migration:

where:

• $p$ = frequency of the dominant allele ($A$)
• $q$ = frequency of the recessive allele ($a$)
• $p^2$ = frequency of homozygous dominant genotype ($AA$)
• $2pq$ = frequency of heterozygous genotype ($Aa$)
• $q^2$ = frequency of homozygous recessive genotype ($aa$)
• Calculation:
• Given: Frequency of $AA = p^2 = 0.64$
• Frequency of dominant allele $A = p = \sqrt{p^2} = \sqrt{0.64} = 0.8$