Degree Type

Thesis

Date of Award

2019

Degree Name

Master of Science

Department

Agronomy

First Advisor

Sotirios V. Archontoulis

Second Advisor

Mark A. Licht

Abstract

Current maize (Zea mays L.) planting date recommendations have not been updated in the state of Iowa since 2001. A state that produced 68.8 million tons of maize on 5.5 million hectares in 2016. It is imperative that this information be regularly updated as both climate and maize hybrid selection are constantly changing. We analyzed maize yield and phenology, from a multi-location, year, relative maturity (RM), and planting date (PD) experiment carried out in Iowa, US. The dataset was used to calibrate a site-specific model (Agricultural Production System sIMulation, APSIM) and extrapolate APSIM results across Iowa, using a region scale model (parallel System for Integrating Impact Models and Sectors, pSIMS). Our objectives were to determine the combination of PD and RM to maximize maize grain yield by environment and to explain the risk associated with the use of full season RM when planting dates are delayed beyond the optimum PD. Additionally, the impact of climate change effects on optimum PD and RM selection by location were examined.

Field scale analysis found slight grain yield differences between full and short season RM on a given PD with yield maximized when planting occurred at or before May 5th. However, running a regional scale model over 36 years, we determined that a static recommendation of optimum PD is not suitable as large variation exists between locations within the state and between years. The coefficient of variation (CV) was 20% and 68% for the optimum PD within and between years respectively. Furthermore, the PD window, or time frame around the optimum PD to achieve 98% of maximum yield, across years was heavily influenced by latitude and RM selection. Overall, this study brings new results to assist decision making regarding PD and RM across Iowa.

Copyright Owner

MitchBaum

Language

en

File Format

application/pdf

File Size

88 pages

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