Free‐Air CO₂ Enrichment and Drought Stress Effects on Grain Filling Rate and Duration in Spring Wheat

Abstract

Wheat grain weight is a function of rate and duration of grain growth and is affected by photosynthate supply. Drought stress reduces photosynthate production because of stomatal closure. However, this might be partially overcome by an increase in air CO2 concentration. This study was conducted to evaluate elevated CO2 and drought stress effects on grain‐filling rate and duration for spring wheat (Triticum aestivum L.). Spring wheat (cv. Yecora Roja) was grown at two CO2 concentrations, 550 (elevated) or 370 (ambient) μmol mol−1 and two water treatments in a Free‐Air CO2 Enrichment (FACE) system at the University of Arizona Maricopa Agricultural Center. Plant samples were collected every 3 to 4 d from 6 d after anthesis until plant maturity. Main stem spikes were separated into upper, middle, and lower sections. Grain weight data for the intact main stem spike, each of its sections, and intact tiller spikes were fitted to a cumulative logistic model. Both elevated CO2 and water treatments significantly influenced the grain‐filling processes. Under drought stress conditions, elevated CO2 increased grain weight in the upper and lower sections of the main stem spike by 10 and 24%, respectively. In well‐watered plants, final grain weight in the midsection of the main stem spike was 8% higher than that measured under drought stress conditions. Grain weight increase under elevated CO2 was due to a faster rate of grain filling. Effects of elevated CO2 on the statistically derived duration of grain filling were inconclusive because of the confounding effect of blower‐induced temperature changes on the process. An increase in grain weight of well‐watered plants was due to a longer grain‐filling period. Later‐formed tiller spikes were more responsive to elevated CO2 and drought stress than main stem spikes. Information from this study will help us understand the grain growth of wheat and provide information to establish grain growth mechanism.

Changes in seed oil and protein contents of maize cultivars at different positions on the ear in response to water limitation

“…1) may be resulted from the short seed filling duration (Ghassemi-Golezani and Lotfi, 2013), as shown for chickpea (Davis et al, 1999), lentil (Erskine, and Ashkar, 1993), wheat (Li et al, 2000), barley (Samarah, 2005), maize (Aparicio-Tejo and Boyer, 1983), soybean (Berevedan and Egli, 2003) and sunflower (Whitfield et al, 1989). Reduced grain filling occurs due to decreased assimilate segregation and activities of sucrose and starch biosynthesis enzymes (Srivastava and Suprasanna, 2015).…”

The effect of CO2 and temperature on Fusarium crown rot incidence, severity, pathogen colonisation, toxigenic potential and host resistance in a selection of wheat germplasm

“…Nicholls (1997) expects that this significant correlation may continue to benefit future wheat yields. This prediction may be rather short sighted as more recent experiments have found the contrary , Ko et al, 2010, Li et al, 2000. Wheat grown in the Yaqui valley in Mexico displayed a remarkable increase in yield from the years following 1951, however yield increases in the eight years preceding 2005 have stagnated .…”

“…This phenomenon is referred to as a "fertilisation effect" and augments photosynthetic efficiency by decreased stomatal conductance and transpiration (Abbad et al, 2004, Chakraborty and Newton, 2011, Li et al, 2000, Li et al, 2004, Wall et al, 2006.…”

“…Moisture stress is a significant abiotic constraint to wheat yield, and precipitation is expected to become limited in many growing areas under climate change (Dai, 2013, Garrett et al, 2011, Li et al, 2000.…”

“…In a report by a 2°C temperature increase in global mean temperature is predicted to reduce Australian wheat yield up to 50 %. Wheat yield reduction due to warming can occur through: reduced seed set per spike ), limited photosynthetic efficiency (Long 1991), and reduced accumulation of grain carbohydrates due to accelerated plant development Fischer 2011;Li et al 2000;Manderscheid et al 2003). Increases in ambient CO2 concentration have been shown to buffer some of the listed negative effects of elevated temperature (Manderscheid et al 2003;Ko et al 2010;Wheeler et al 1996) by reducing stomatal conductance, decreasing evapotranspiration, and increasing photosynthetic rate, equating to an increased water use efficiency.…”