Prediction of Flowering Dates in Maize Based on Different Methods of Estimating Thermal Units¹

Abstract

In an attempt to find better ways of estimating relative maturity differences in corn (Zea mays L.), various thermal unit formulas were evaluated. Utilizing data from six plantings of corn over a 2 year period, 22 different methods of computing thermal units were tested for their ability to account for variation in flowering dates. Both hourly and daily temperature data were used in the equations. In general the daily measurements appeared to be approximately as accurate as the hourly measurements. The best equation for predicting flowering dates on the basis of thermal units utilized a base temperature of 10C (50F) and an optimum of 30C (86F). The excess temperature above 30C was subtracted to account for high temperature stress.

Maize early endosperm growth and development: From fertilization through cell type differentiation

“…T , where T MAX was the mean daily high, T MIN was the mean daily low, and T BASE was, as previously described for maize ( Cross and Zuber, 1972 ), set to 10 ° C.…”

Adapting maize production to climate change in sub-Saharan Africa

“…Average optimum temperatures for temperate, highland tropical and lowland tropical maize lie between 20 and 30°C, 17 and 20°C, and 30 and 34°C, respectively (Badu-Apraku et al 1983;Brown 1977;Chang 1981;Chowdhury and Wardlaw 1978;Cross and Zuber 1972;Dale 1983;Jiang et al 1999;Jones et al 1984;Shaw 1983). Maximum temperatures currently exceed optimal temperature conditions for lowland tropical maize (34°C) in several countries (Burkina Faso, Chad, Eritrea, Gambia, Mali, Mauritania, Niger, Nigeria, Senegal and Sudan), however the area of maize grown within several of these regions is small.…”

Spatial-Temporal Simulation of LAI on Basis of Rainfall and Growing Degree Days

“…Since 1730 when Reaumur introduced the concept of heat units, or thermal time, many methods of calculating heat units have been used successfully in agricultural and natural resources sciences [29]. Particularly in the areas of crop phenology and development, the concept of heat units, measured in GDD, has vastly improved description and prediction of phenological events compared to other approaches such as time of year or number of days e.g., [30,31]. The heuristic indicator of GDD is calculated by summing up the positive daily differences between mean temperature and a baseline temperature [32,33].…”