Response of wheat restricted‐tillering and vigorous growth traits to variables of climate change

Abstract

The response of wheat to the variables of climate change includes elevated CO2, high temperature, and drought which vary according to the levels of each variable and genotype. Independently, elevated CO2, high temperature, and terminal drought affect wheat biomass and grain yield, but the interactive effects of these three variables are not well known. The aim of this study was to determine the effects of elevated CO2 when combined with high temperature and terminal drought on the high-yielding traits of restricted-tillering and vigorous growth. It was hypothesized that elevated CO2 alone, rather than combined with high temperature, ameliorates the effects of terminal drought on wheat biomass and grain yield. It was also hypothesized that wheat genotypes with more sink capacity (e.g. high-tillering capacity and leaf area) have more grain yield under combined elevated CO2, high temperature, and terminal drought. Two pairs of sister lines with contrasting tillering and vigorous growth were grown in poly-tunnels in a four-factor completely randomized split-plot design with elevated CO2 (700 µL L(-1)), high day time temperature (3 °C above ambient), and drought (induced from anthesis) in all combinations to test whether elevated CO2 ameliorates the effects of high temperature and terminal drought on biomass accumulation and grain yield. For biomass and grain yield, only main effects for climate change variables were significant. Elevated CO2 significantly increased grain yield by 24-35% in all four lines and terminal drought significantly reduced grain yield by 16-17% in all four lines, while high temperature (3 °C above the ambient) had no significant effect. A trade-off between yield components limited grain yield in lines with greater sink capacity (free-tillering lines). This response suggests that any positive response to predicted changes in climate will not overcome the limitations imposed by the trade-off in yield components.

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

“…There was no difference in grain yield between the two sister lines contrasting in tillering under any treatment, despite the presence of more tillers in the free-tillering line under elevated CO 2 . Although tillering in the restricted-tillering line was not affected by elevated CO 2 or high temperature, leaf extension, and leaf area do respond to elevations in CO 2 ( Dias de Oliveira et al, 2015 ) as well as leaf photosynthetic rates. Therefore, total canopy photosynthesis was probably similar between both lines.…”

“…In a previous study, grain yield in a free-tillering wheat line, with the potential to increase sink capacity, did not differ from its isogenic restricted-tillering line, with lower sink capacity. This was because the free-tillering line increased grain number per unit area due to elevated CO 2 , but had smaller grains ( Dias de Oliveira et al, 2015 ), presumably due to the negative correlation between grain number per unit area and grain size ( Grafius, 1972 ). Increasing grain number in wheat is considered critical for improving grain yield ( Fischer and Aguilar, 1976 ; Fischer, 1985 , 2011 ), but it is also likely that grain yield improvement may be limited by grain size ( Grafius, 1972 ; Rajaram and Ginkel, 1996 ; Acreche and Slafer, 2006 ).…”

“…Elevated CO 2 increases the assimilation of carbon in wheat ( Habash et al, 1995 ) and presumably the availability of carbon assimilates for floret development ( Marc and Gifford, 1984 ), potential grain number, and hence, more grains per unit area. Elevated CO 2 often increases grain number per ear, possibly due to increased floret production and/or a reduction in floret death ( Musgrave and Strain, 1988 ; Manderscheid and Weigel, 1997 ; Dias de Oliveira et al, 2013 , 2015 ). However, in some cases no CO 2 effect on grain number per ear have been reported ( Högy et al, 2009 , 2013 ), presumably reflecting genotypic variability to treatment.…”

Cereal progenitors differ in stand harvest characteristics from related wild grasses

“…Research into grass architecture using phylogenetic and genomic methods has shown similarities between different cereal crops, with the tendency for crops to have taller, straighter growth and apical dominance, in contrast to their wild relatives (Doust, 2007;Fuller et al, 2010). Improvements to tiller economy are currently underway in modern crop breeding, with particular interest in the tin gene in wheat, which when manipulated, produces plants with fewer tillers, larger spikes and more seeds than wildtype in drought and elevated CO 2 conditions (Dias de Oliveira, Siddique, Bramley, Stefanova, & Palta, 2015;Mitchell, Rebetzke, Chapman, & Fukai, 2013;Tausz-Posch et al, 2015).…”

Elevated temperature reduces wheat grain yield by increasing pests and decreasing soil mutualists

“…In our study, changes in the plant growth time, such as shortening of the tillering stage would result in reduction of production. Moreover, if elevated temperatures happen during the time from heading stage to maturing stage, the heat stress can decrease post‐heading duration and grain yield, because there is also a significant positive correlation of post‐heading duration with tillers and grain number density . Elevated temperature may also impact grain quality, such as wet gluten, nitrogen, and soluble sugar, because leaf expansion, photosynthesis and grain filling are key temperature dependent physiological processes .…”