R&D News & Views 11 January 2017
Ricardo Antunes
What impact when abiotic stresses combine?
Next month I reach my 2 year anniversary as Technical Manager for Brazil with Plant
Impact. My move from Syngenta enabled me to focus on the exciting new field of crop
enhancement (or crop efficiency – the label seems to vary) and has presented some
opportunities to work with brilliant scientists and marketing professionals committed to
helping close the global yield gap. Recently I spotted a fascinating paper on plant stress
combinations from Ron Mittler of the University of Nevada which I’m sure will interest my
colleagues and contacts too – so I thought I’d share it here.
We already understand that environmental stress conditions such as drought, heat, salinity,
cold, or pathogen infection can have a devastating impact on plant growth and yield under
field conditions. In fact, satellite images in August 2002 in the USA estimate a US$ 4.2 billion
a damage in agriculture was caused by a combination of heat and drought stress.
Ron Mittler’s paper points out that current breeding programs to develop abiotic stress
tolerant plants focus their researches in isolated factors such as heat, salinity, drought and
so on. However, in the field plants are subjected to more than a single stress. Due to this
combination, the negative impact can be much stronger than each of them isolated.
In case studies in corn, sorghum, barley and other grasses combining heat and drought
stress, it was found that there was a greater detrimental effect on growth and yield when
compared to each of the stresses isolated.
Among many reasons that might lead to these losses, it was found that combined defense
mechanisms adopted by plants can generate antagonistic responses. Under heat stress, for
example, plants open leaves’ stomata to reduce temperature by transpiration. However if
drought stress is combined, the stomata won’t open and the leaves temperature would be
higher. Just these simple two mechanisms can change many plant physiological processes
and damage its development.
Damages caused by combined abiotic stresses underpin the need to develop crops with
enhanced tolerance and inputs that help crops to mitigate stresses, alone and in
combination. This area of agricultural research continues to develop and offer new
challenges and opportunities to sustainably improve crop yields.
Perhaps a deeper understanding about the interaction between current environment
extreme conditions and plant stress defense mechanisms, opens wide a research field on
further plant breeding and crop enhancement technology developments, stablishing a new
baseline in the search for the maximum productive potential.