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United States Department of Agriculture

Agricultural Research Service

Title: PHENOLOGICAL RESPONSES OF WHEAT AND BARLEY TO WATER AND TEMPERATURE: IMPROVING SIMULATION MODELS

Authors
item McMaster, Gregory
item Wilhelm, Wallace

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2003
Publication Date: December 15, 2003
Citation: Mcmaster, G.S., Wilhelm, W.W. 2003. Phenological responses of wheat and barley to water and temperature: improving simulation models. Journal of Agricultural Science. Volume 141, pg 129-147.

Interpretive Summary: Understanding and predicting wheat and barley growth stages is becoming an increasingly important technique for enhancing management practices. Recent attempts to improve phenology submodels in crop simulation models have focused on improving the description of phenological responses to water stress and the interpretation and understanding of thermal time. Our objectives were (1) to provide data to better determine the qualitative and quantitative response of wheat and barley to water stress and (2) where to measure temperature to improve understanding and predictions of growth stages. Three experiments were conducted. The first tested the phenological responses of 12 cultivars of winter wheat to water stress for two seasons at two sites. The second tested the timing of water stress on spring barley phenological responses for two years at two sites. In a third experiment, soil near the shoot apex at crown depth was heated 3o C above ambient soil temperature for a spring wheat grown in the field for two years with three planting dates each year. The general response of wheat and barley to water stress was to reach growth stages earlier, with the most significant response for the grain filling period. Little response to water stress was found for jointing and flag leaf complete/booting growth stages. Thermal time to jointing was highly variable with location, but consistent for successive growth stages. Most winter wheat cultivars followed this general response pattern for most site-years, but inconsistencies were found suggesting a complicated cultivar by environment (C X E) interaction that makes improving phenology submodels for all cultivars difficult. The C x E interaction was most prominent for anthesis (A) and maturity (M) growth stages. Results of heating the soil at the shoot apex depth were completely unexpected: heating the soil did not speed spring wheat phenological development. These results suggest caution in allocating effort and resources to measuring or estimating soil temperature rather than readily available air temperature as a means of universally improving our phenology submodels. These results help quantify the response of wheat to water stress and thermal time for improving our crop simulation models and management.

Technical Abstract: Understanding and predicting small-grain cereal development is becoming an increasingly important technique for enhancing management practices. Recent attempts to improve phenology submodels in crop simulations have focused on improving the description of phenological responses to water stress and the interpretation and understanding of thermal time. Our objectives were to provide data to better determine the qualitative and quantitative response of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) to water stress and where (in space) to measure temperature to provide a starting point for improving the portrayal of small grain development in phenological submodels. Three experiments were conducted; the first tested the phenological responses of 12 cultivars of winter wheat to water stress for two seasons at two sites. The second tested the timing of water stress on spring barley phenological responses for two years at two sites. In a third experiment, soil near the shoot apex at crown depth was heated 3o C above ambient soil temperature for a spring wheat grown in the field for two years with three planting dates each year. The general response of wheat and barley to water stress, which was to reach the growth stage earlier, was quantified; the most significant response was for the grain filling period. Little response to water stress was found for jointing and flag leaf complete/booting growth stages. Thermal time to jointing was highly variable with location, but consistent for successive growth stages. Most winter wheat cultivars followed this general response pattern for most site-years, but inconsistencies were found suggesting a complicated genotype by environment (G X E) interaction that makes improving phenology submodels for all cultivars difficult. The G x E interaction was most prominent for anthesis (A) and maturity (M) growth stages. Results of heating the soil at the shoot apex depth were completely unexpected: heating the soil did not speed spring wheat phenological development. These results, and others cited, suggest caution in allocating effort and resources to measuring or estimating soil temperature rather than readily available air temperature as a means of universally improving our phenology submodels. These results help quantify the response of wheat to water stress and thermal time for improving our crop simulation models and management.

Last Modified: 10/31/2014
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