Elevated CO2 Reduced Floret Death in Wheat Under Warmer Average Temperatures and Terminal Drought

Abstract

Elevated CO2 often increases grain yield in wheat by enhancing grain number per ear, which can result from an increase in the potential number of florets or a reduction in the death of developed florets. The hypotheses that elevated CO2 reduces floret death rather than increases floret development, and that grain size in a genotype with more grains per unit area is limited by the rate of grain filling, were tested in a pair of sister lines contrasting in tillering capacity (restricted- vs. free-tillering). The hypotheses were tested under elevated CO2, combined with +3°C above ambient temperature and terminal drought, using specialized field tunnel houses. Elevated CO2 increased net leaf photosynthetic rates and likely the availability of carbon assimilates, which significantly reduced the rates of floret death and increased the potential number of grains at anthesis in both sister lines by an average of 42%. The restricted-tillering line had faster grain-filling rates than the free-tillering line because the free-tillering line had more grains to fill. Furthermore, grain-filling rates were faster under elevated CO2 and +3°C above ambient. Terminal drought reduced grain yield in both lines by 19%. Elevated CO2 alone increased the potential number of grains, but a trade-off in yield components limited grain yield in the free-tillering line. This emphasizes the need for breeding cultivars with a greater potential number of florets, since this was not affected by the predicted future climate variables.

Vandenyje tirpių angliavandenių kaupimasis kviečio žiedynkotyje ir jų ryšys su morfoanatominiais bei produktyvumo požymiais

“…Average grain weight reduction across 44 genotypes and two years due to leaf blades removal was 19% (Dodig et al, 2016), which agrees well with results of the wheat experiments in field conditions under natural terminal drought (Amiri et al, 2013;Dias de Oliveira et al, 2015).…”

Stomatal Development and Conductance of a Tropical Forage Legume Are Regulated by Elevated [CO2] Under Moderate Warming

“…In our study, eCO 2 improved WUE in very different conditions of soil moisture and ambient temperature levels, indicating that S. capitata has the potential to adjust to future conditions of temperature and soil water availability. Very few studies have combined high [CO 2 ], warming, and drought together (Dias de Oliveira et al, 2013), and in wheat ( Triticum aestivum , Poaceae) interactions between all three variables on WUE , photosynthesis, and biomass were not found (Dias de Oliveira et al, 2015a,b). However, further studies are necessary to better understand the interactions between CO 2 × drought × warming on plants’ water use and how different physiological parameters co-vary within climatic variation.…”

Implications of High Temperature and Elevated CO2 on Flowering Time in Plants

“…However, interactions between e[CO 2 ] and temperature or photoperiod on flowering time can't be generalized and may be specific to a localized environment or plant species. Crops response to combined elevated CO 2 and high temperature has been primarily quantified using controlled environment chambers (Madan et al, 2012 ) or poly tunnels (Dias de Oliveira et al, 2013 , 2015a , b ), wherein other interacting environmental factors such as wind speed, radiation could be considerably different compared to field conditions (Bahuguna et al, 2015 ). Developing economically feasible facilities to test this combined environmental change on field crops has been a major challenge and hence there is limited information on crops responses to this interaction under field conditions.…”