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Advances in Meteorology
Volume 2017, Article ID 7164068, 11 pages
Research Article

Mapping of Maize Growing Period over the Free State Province of South Africa: Heat Units Approach

1Agricultural Research Council, Institute for Soil, Climate and Water, Private Bag X79, Pretoria 0001, South Africa
2Risks and Vulnerability Assessment Center, University of Limpopo, Private Bag X1106, Sovenga 727, South Africa

Correspondence should be addressed to Mokhele Edmond Moeletsi; az.cirga.cra@misteleom

Received 16 December 2016; Accepted 23 February 2017; Published 19 March 2017

Academic Editor: Herminia García Mozo

Copyright © 2017 Mokhele Edmond Moeletsi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Temperature is one of the important environmental parameters that determines the development of a crop from one stage to another. It is integral in the calculation of heat units. In this study, the thermal index concept is used to determine the length of the growing period of short season, medium season, and medium-late season maize crop varieties for different sowing dates (1st dekad of October to 1st dekad of January). The results show high spatiotemporal variation in the median growing period for all three maize varieties. The length of the growing period for the short, medium, and medium-late season varieties is relatively short during October to early December with values in some areas of less than 100, 120, and 120 days, respectively. The duration of the planting period increases exponentially in most places starting from the 2nd dekad of November to 2nd dekad of December, depending on the region and crop variety. Long growing periods are likely to align maize growing period with dates of high frost risk and water shortages. Thus, appropriate choice of sowing date taking into consideration the thermal time requirements of the cultivar is crucial for proper growth and development of the maize crop.