ICAR AICE-JRF/SRF Climate Change Impacts on Agriculture & Food Systems: practice questions

1 · Temperature, heat stress and crop phenology · easy

A maize crop experiences Tmax = 32 °C and Tmin = 18 °C on one day. Using the simple averaging method with a base of 10 °C and no upper cap, how many growing degree days accumulate?

1. 7
2. 14
3. 25
4. 15

2 · Temperature, heat stress and crop phenology · hard

Statistical studies of United States county yields found maize yield rising with temperature up to a threshold and falling steeply above it. Which threshold matches that finding?

1. About 39 °C for maize
2. About 19 °C for maize
3. About 10 °C for maize
4. About 29 °C for maize

3 · CO2 fertilisation, C3 and C4 responses and nutritional quality · hard

Why did FACE experiments give smaller crop yield increases from elevated carbon dioxide than earlier enclosure studies?

1. Enclosures altered microclimate, rooting and light, inflating responses that FACE avoided
2. Enclosures measured biomass only, and biomass never increases under elevated carbon dioxide
3. FACE plots received less carbon dioxide than their target, so the true response was never measured
4. FACE used only C4 crops, which respond weakly, whereas enclosures used only C3 crops throughout

4 · Drought, floods and changing rainfall patterns · easy

Which type of drought is defined by soil moisture too low to meet crop needs?

1. Meteorological drought
2. Hydrological drought
3. Socioeconomic drought
4. Agricultural drought

5 · Drought, floods and changing rainfall patterns · medium

What is 'peak water' in a glacier-fed river basin?

1. The maximum water a crop can transpire on the hottest day of an average growing season
2. The point at which irrigation demand equals rainfall, so no further storage is needed
3. The highest flood level recorded in a basin, used as the design level for embankments
4. Meltwater flow first rises as glaciers shrink, then falls as the ice runs out

6 · Climate and pests, diseases and weeds · medium

Aflatoxin contamination of maize and groundnut tends to increase under which conditions?

1. Waterlogged soils during tillering combined with very high soil nitrogen
2. Elevated carbon dioxide with ample rainfall throughout the growing season
3. Heat and drought during grain filling, and poor drying after harvest
4. Cool, cloudy weather at sowing followed by early frost before maturity

7 · Climate and pests, diseases and weeds · hard

In a maize field, rising carbon dioxide alone would be expected to favour which weeds most?

1. C3 broadleaf weeds, because their photosynthesis responds to CO₂ more than the C4 crop does
2. Parasitic weeds only, because they draw extra CO₂ directly from the host crop's vascular system
3. C4 grass weeds, because their photosynthesis responds to CO₂ much more than C3 plants do
4. No weeds, because elevated CO₂ suppresses germination of all weed seeds in the soil seed bank

8 · Methods: field experiments, FACE, statistical and process models · easy

What is the 'chamber effect' in open-top chamber experiments?

1. The noise made by chamber fans, which is known to slow the growth of seedlings
2. The effect of a chamber's colour on the flowering date of plants nearby outside
3. The release of CO₂ by chamber walls as they age in sunlight over several seasons
4. Altered temperature, humidity and wind inside that confound the treatment

9 · Methods: field experiments, FACE, statistical and process models · medium

What is the main advantage of field infrared heaters over enclosures for warming experiments?

1. They warm only the soil, so above-ground processes are left completely unchanged
2. They have no side effects, perfectly reproducing future climate in all respects
3. They raise carbon dioxide at the same time, so two factors are tested at once
4. They warm the canopy in the open without altering wind and light by enclosure

10 · Regional vulnerability and climate hotspots · hard

Why should index-based vulnerability assessments be read as screening tools rather than precise rankings?

1. Indices use satellite data only, which cannot measure any human characteristic
2. Indices are calculated once per century and so are always out of date
3. Indices measure only hazards and never include exposure or adaptive capacity
4. Results depend heavily on which indicators are chosen and how each of them is weighted