Prelims · Geography · 47 questions

Agriculture & crops

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Prelims 2017 · Q45

Easy

With reference to agriculture in India, how can the technique of ‘genome sequencing’, often seen in the news, be used in the immediate future?

1.Genome sequencing can be used to identify genetic markers for disease resistance and drought tolerance in various crop plants.
2.This technique helps in reducing the time required to develop new varieties of crop plants.
3.It can be used to decipher the host-pathogen relationships in crops.

Select the correct answer using the code given below:

Answer & explanation

Answer: (d) 1, 2 and 3

All three uses are correct. Reading a crop's full DNA reveals markers for traits such as drought tolerance and disease resistance, cuts the years needed to breed a new variety, and shows how crops and their disease-causing organisms interact.

✓ 1. When 90 chickpea genomes were sequenced, the work gave millions of genetic markers that can be used to breed varieties with better drought tolerance and disease resistance.
✓ 2. Breeding a new chickpea variety normally takes 4–8 years; the scientists behind the chickpea genome said the sequence could cut this to half.
✓ 3. Sequencing crop and pathogen genomes lets researchers study plant–pathogen interactions and plant resistance at gene level.

Remember · Genome sequencing in crops: finds trait markers (drought, disease resistance), speeds up breeding (chickpea: 4–8 years cut to about half) and reveals host–pathogen interactions.

Sources

Global research team decodes genome sequence of 90 chickpea lines, ICAR ↗ · reference work “Re-sequencing of additional 90 genotypes provided millions of genetic markers and low diversity genome regions that may be used in the development of superior varieties with enhanced drought tolerance and disease resistance. … At the moment, it takes 4-8 years to breed a new chickpea variety. This genome sequence could reduce to half the time to breed for a new variety with market-preferred traits.”
Integrated Molecular and Bioinformatics Approaches for Disease-Related Genes in Plants, PMC (US National Library of Medicine) ↗ “The progress in the sequencing of agriculturally important crops has made it possible to develop a better understanding of plant–pathogen interactions and plant resistance.”

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2017 · Q71

Medium

Which of the following practices can help in water conservation in agriculture?

1.Reduced or zero tillage of the land
2.Applying gypsum before irrigating the field
3.Allowing crop residue to remain in the field

Select the correct answer using the code given below:

Answer & explanation

Answer: (c) 1 and 3 only

Leaving the soil undisturbed (reduced or zero tillage) and leaving crop residue on the field both conserve water, because the residue cover cuts evaporation and lets more rain soak in. Gypsum is a soil amendment for sodic soils, not a water-saving practice.

✓ 1. No-till or reduced tillage, together with residue mulch, is the basis of conservation farming because it conserves water and prevents erosion.
✗ 2. Gypsum supplies soluble calcium to replace exchangeable sodium in sodic soils. It is used to reclaim such soils and is not a way of saving irrigation water.
✓ 3. Crop residue left on the soil surface reduces evapotranspiration (water loss to the air), raises infiltration rates and suppresses weeds.

Remember · Water-saving conservation farming: minimum or no tillage plus a residue mulch. Gypsum is for reclaiming sodic soils, not for saving water.