Genotypic adaptation of Indian groundnut cultivation to climate change:an ensemble approach

Climate change has been projected to significantly affect agricultural productivity and
hence food availability during the 21st century, with particularly negative effects across the
global tropics. However, the uncertainty associated with projecting climate change impacts
is a barrier to agricultural adaptation. The work reported in this thesis is a contribution
to the understanding of genotypic adaptation to near-term (i.e. 2030s) climate change
and many of the associated uncertainties, using model ensembles. This work focuses on
Indian groundnut and uses the General Large Area Model for annual crops (GLAM) and
the EcoCrop niche model to investigate the response of groundnut under future climate
scenarios, and to develop a genotypic adaptation strategy.
Under the future representative concentrations pathway (RCP) 4.5, robust positive climate
change impacts on crop productivity were found in 3 (western, northern and south-eastern)
out of 5 groundnut growing regions. From the remainder of regions, one presented robust
negative impacts and in the other uncertainties precluded a robust statement being made
about productivity changes. Yield gains were associated with seasonal precipitation increases,
a lower frequency of occurrence of terminal drought and its effect on cropping
season length. Yield loss in central India was associated with less radiation interception
and reductions in crop duration, whereas in the south there was large uncertainty due to
temperature biases in GCMs triggering (or not) heat stress during anthesis. The latter
result suggests that decisions of whether to correct or not GCM biases and the method of
correction may be at least as important as the choice of climate scenario, or the choice of
crop model parameters.
Adaptation simulations indicated that the most critical traits for groundnut adaptation
under future scenarios are increases in maximum photosynthetic rates, greater partitioning
to seeds and, where enough soil moisture is available, also increases in the maximum
transpiration rate. Changes to crop duration were beneficial if durations did not exceed
those of the baseline, and hence allowed for enough water uptake at the end of the cropping
season. Yield gains in adaptation scenarios were particularly large in eastern and northern
India, and more moderate across the rest of the country.