Simulating Crop Phenological Responses to Water Stress Using the PhenologyMMS Software Program

Crop phenology is fundamental for understanding crop growth and development, and increasingly influences many agricultural management practices. Water deficits are one environmental factor that can influence crop phenology through shortening or lengthening the developmental phase, yet the phenological responses to water deficits have rarely been quantified. The objective of this article is to describe the science and general evaluation of a decision support technology software tool, PhenologyMMS (Modular Modeling Software) V1.2. PhenologyMMS was developed to simulate the phenological response of different crops to varying levels of soil water. The program is intended to be simple to use, requires minimal information for calibration, and can be easily incorporated into other crop simulation models. New and revised developmental sequences of the shoot apex correlated with phenological events and the response to soil water availability are provided for proso millet (Panicum milaceum L.), hay/foxtail millet [Setaria italica (L.) P. Beauv.], sunflower (Helianthus annuus L.), and sorghum (Sorghum bicolor L.). Model evaluation consisted of testing algorithms using "generic" default phenology parameters for a crop (i.e., no calibration for specific cultivars was used) for a variety of field experiments to predict developmental events such as seedling emergence, floral initiation, flowering, and physiological maturity. Additionally, an application of the program predicting mean dates of winter wheat (Triticum aestivum L.) phenology across the Central Great Plains based on historical weather records is presented. Results demonstrated that PhenologyMMS has general applicability for predicting crop phenology and offers a simple and easy to use approach to predict and understand how phenology responds to varying water deficits. PhenologyMMS software may be downloaded from http://www.ars.usda.gov/services (select "Software") or http://arsagsoftware.ars.usda.gov.