99267 Wheat Physiology and Yield Unaltered By Climatic Pressures.
Poster Number 458-1315
See more from this Division: C02 Crop Physiology and Metabolism
See more from this Session: Crop Physiology and Metabolism Poster
Abstract:
It was hypothesized that physiological and agronomic performance metrics would closely follow fluctuations in precipitation and rising atmospheric CO2 levels; however, the analyses indicate that wheat yields have not been affected by seasonal precipitation or atmospheric [CO2]. These findings contrast with previous experimental results that show biomass burgeoning with elevated [CO2]. The discrepancy may be attributed to the near-immediate increase in [CO2] in controlled experiments, as opposed to a gradual shift under field conditions, implicating less of a yield impact from elevated [CO2] than initially reported.
Over the observed time period, physiological performance and yield are responding more strongly to agronomic decisions than to climatic pressures. For example, the difference between isotopic signatures of atmospheric and plant carbon pools (Δ13C) depends on fertilizer inputs, suggesting that soil treatments are affecting plants’ water-use efficiency. At any given yield, wheat receiving nitrogen from crop residues is more enriched in carbon-13 than wheat receiving nitrogen as mineral fertilizer. This result indicates the former plants transpired less and wheat receiving organic nitrogen had about 3% higher water-use efficiency.
The current study did not find significant relationships between yield and seasonal precipitation or atmospheric [CO2], indicating climatic conditions throughout the study never reached a threshold for declining physiological performance. Analysis of precipitation values, carbon isotope data, and grain isotope signatures all support the assertion that the conditions experienced over the 23-year experiment did not encompass severe drought stress.
See more from this Division: C02 Crop Physiology and Metabolism
See more from this Session: Crop Physiology and Metabolism Poster