Maize ear temperature

An experimental study of ear temperature was made in Morocco (June, 1997) and in Belgium (September, 1998). Measurements were made at mid-length of ear in the centre of cob and at different points in the middle of grains. The results showed that temperature in the middle of the grains depends significantly on the position of grain around the ear axis, especially in Morocco, between 13 and 16 h (UT). The result obtained shoed that, because of the considerable ear thermal inertia and non-isotropic direction of the direct solar radiation, the average temperatures in the middle of the grain and in the centre of the cob were similar. The difference between grain and air temperature was shown to be clearly more affected by solar radiation than by wind speed. The protection of ear against direct solar radiation led to an average temperature reduction of about 2.1°C in ear protected compared with normal ears. Also, the important role played by the canopy on ear temperature was underlined. A temperature difference of up to 8.5°C was observed between the temperature of ears exposed to direct radiation and other (normal) ears. The effects of the differences observed between grain temperatures on both final weight grain and kernel growth rate were calculated using CERES-Maize functions. These effects were shown unlikely to affect drastically grain yield.