Conclusions
The current study examined the effects of growth temperature, water
deficit and heatwave on leaf carbon gain and biomass production in
cotton plants. Warmer growth temperature promoted growth rate and leaf
level carbon gain due to greater stomatal conductance and thermal
acclimation of photosynthesis, but compromised aboveground dry mass
production. Furthermore, growth temperature affected the response of
leaf carbon gain and/or yield to nocturnal warming and heat stress.
Water stress also exerted control over carbon gain and reproductive dry
matter, either independently or interactively, but these effects were
less pronounced. The instantaneous impacts of the heatwave on carbon
gain and biomass production was largely neutralized, yet fruit biomass
was negatively affected.
Overall, temperature appears to be a major determinant of biomass
production in cotton. More specifically, both short- and long-term
increases in daytime temperature will lead to reduced cotton yields,
while nocturnal warming has limited capacity to alter that impact.
Additionally, yield will not be strongly diminished if soil water
content is maintained well above the level triggering leaf wilting.
Therefore, plant traits enabling heat tolerance especially for heatwave
conditions should continually be targeted and prioritized in future
breeding selection. This study adds to the current knowledge about the
impacts of global climate change on cotton by providing evidence of the
response of carbon gain and biomass to some of the key climate change
factors, and highlights the interactive effects of environmental factors
on plant growth. Subsequent studies in the field are required to more
fully uncover the mechanisms that can be used to model crop yield under
future climates.
Conflict of interest: The authors declare that they have no
conflict of interest.