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United States Department of Agriculture

Agricultural Research Service

Title: Simulating Water Stree Responses in Crop Phenology Models

Author
item McMaster, Gregory

Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 20, 2004
Publication Date: September 14, 2004
Citation: Mcmaster, G.S. 2004. Simulating water stree responses in crop phenology models. Symposium Proceedings. International Symposium. Perth, Australia. September 2004.

Interpretive Summary: Understanding and predicting crop phenology, or the growth stages a crop follows from planting to harvest, is fundamental to crop management. While temperature is usually the critical environmental factor driving phenology, other factors (particularly water) can play a secondary role. Quantifying water stress responses has received less attention than temperature. This paper describes the status of a computer simulation model for predicting crop phenology (Phenology MMS) that can be used independently or incorporated into existing crop growth models. This new model synthesizes and quantifies the entire developmental sequence of the shoot apex, or growing point, of many crops, making this information readily available to users with limited knowledge of phenology or the crop of interest. A Java-based interface allows the user to interact with the underlying Fortran simulation model. Developmental sequences are quantified using thermal time (either growing degree-days or number of leaves). The user chooses default values for a cultivar or changes the values as desired. Stress responses are most simply incorporated by selecting for either optimal or stressed conditions that changes the thermal time estimates appropriately. Greater refinement of thermal estimates is possible when more information is available. It is also important to understand the effects of specific stresses on specific growth stages or developmental processes. Based on previous research, wheat and barley phenological responses have been quantified where water stress prior to jointing has little effect, and the effect increases progressively for later growth stages reaching a maximum for grain filling duration. For maize, a critical effect of water stress is on increasing the anthesis-silking thermal time interval.

Technical Abstract: Understanding and predicting crop phenology is fundamental to crop management. While temperature is usually the critical environmental factor driving phenology, other factors (particularly water) can play a secondary role. Quantifying water stress responses has received less attention than temperature. This paper describes the status of a model for predicting crop phenology (Phenology MMS) that can be used independently or incorporated into existing crop growth models. This new model synthesizes and quantifies the entire developmental sequence of the shoot apex of many crops, making this information readily available to users with limited knowledge of phenology or the crop of interest. A Java-based interface allows the user to interact with the underlying Fortran simulation model. Developmental sequences are quantified using thermal time (either growing degree-days or number of leaves). The user chooses default values for a cultivar or changes the values as desired. Stress responses are most simply incorporated by selecting for either optimal or stressed conditions that changes the thermal time estimates appropriately. Greater refinement of thermal estimates is possible when more information is available. It is also important to understand the effects of specific stresses on specific growth stages or developmental processes. Based on previous research, wheat and barley phenological responses have been quantified where water stress prior to jointing has little effect, and the effect increases progressively for later growth stages reaching a maximum for grain filling duration. For maize, a critical effect of water stress is on increasing the anthesis-silking thermal time interval.

Last Modified: 4/19/2014