Free‐Air CO₂ Enrichment Effects on Rate and Duration of Apical Development of Spring Wheat

Abstract

Rates and durations of individual phases of wheat (Triticum aestivum L.) apical development are among the most important factors that determine yield components. Because atmospheric CO2 has been increasing steadily, it is important to evaluate the effects of elevated CO2 on wheat development. This study was conducted to determine rates and durations of leaf, spikelet, and floret primordium initiation in a Free‐Air Carbon Dioxide Enrichment (FACE) system. Spring wheat (cv. Yecora Roja) was planted at the University of Arizona Maricopa Agricultural Center. The two CO2 concentrations were 550 (elevated) and 370 (ambient) μmol mol−1 CO2. Individual plant samples were collected every 3 to 4 d. We dissected the main stem (MS), coleoptile tiller (T0), primary tillers (T1, T2, and T3) and secondary tillers (T00, T01, T02, T10, Tll, and T12) and counted primordia. Apex primordium data were fitted to a four‐piece linear‐spline segmented regression model with the SAS proc NLIN. No influence of elevated CO2 (550 μmol−1 on leaf primordium initiation of MS was detected. Nevertheless, CO2 enrichment significantly increased rates of spikelet primordium initiation of MS, T1, T2, T10, and Tll, and diminished the durations of spikelet development phase of MS, TI, T2, T3, T10, and T11. Within the floret phase, CO2 enrichment significantly increased rates of floret primordium initiation of MS, TO, T1, T2, and T3, and diminished the time to the completion of floret primordium initiation of MS, T0, T1, T3, and T11. The information from this study will be utilized to predict wheat apical development and grain production in the elevated atmospheric CO2 environments of the future.

Interactive Effects of Elevated Carbon Dioxide and Drought on Wheat

“…An increase in both WUE and IWUE, ample TNC pools and as much as a 1.5°C warmer uppermost canopy sunlit leaf temperature reported herein (Table 3), and a0.6°C increase in whole‐canopy temperature reported in a companion study (Kimball et al, 1995; Pinter et al, 2000), can explain the elevated C a –induced increase in the initiation and growth of organs during seedling development (Li et al, 1997), an advantage that persisted throughout the remainder of the growing season (Kimball et al, 1995; Pinter et al, 1996). Elevated C a caused an increase in A ′ (Fig.…”

“…9), which explains the 19 and 44% stimulation of whole‐canopy net assimilation rate reported for well‐watered and water‐stressed wheat canopies, respectively (Kimball et al, 1995). Any C a –induced enhancement in TNC reserves ensured that actual growth approximated that of potential (Li et al, 1997, 1999). It also ensured that any adaptation to drought (Turner and Long, 1980) that would require additional carbon supply was more likely to occur in water‐stressed leaves grown in elevated C a An enhancement in drought adaptations because of elevated C a (Wall, 2001; Wall et al, 2001a) minimized water loss and resulted in less negative Ψ W (Fig.…”

Interactions between increasing CO2 concentration and temperature on plant growth

“…2500 μ mol mol –1 , Grotenhuis & Bugbee 1997) and only small or zero effects on the phyllochron have been reported (e.g. Frank & Bauer 1996; Batts et al 1996, 1997; Li et al 1997; Slafer & Rawson 1997). In rice increased [CO 2 ] produced shorter phyllochron intervals in some experiments (Imai, Coleman & Yanagisawa 1985; Ingram et al 1995), but not in others (Allen et al 1995; Baker et al 1996; Ziska et al 1997).…”

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

“…Elevated CO 2 may have also reduced floret death, or grain abortion (increased grain-set) after anthesis (Gifford, 1979). It has been suggested that temperature, light, and soil moisture may be more important than CO 2 concentration for floret primordial initiation and development (Whingwiri & Stern, 1982;Longnecker et al, 1993;Li et al, 1997) and spikelet fertility (Frank & Bauer, 1996) in spring wheat. The interactive effect of CO 2 by temperature, and main effect of elevated CO 2 on grain-set in wheat is not well-known.…”