Relationship between Crop Temperature and the Physiological and Phenological Development of Differentially Irrigated Corn¹

Abstract Quantitative data relating crop temperature under different water stress conditions to the phenological and physiological development of corn ( Zea mays L.) over a growing season are lacking. This study was motivated by the need to obtain quantitative information which can be beneficially utilized by those involved in predicting crop yields and to assist those who assess the economic impact of drought on crop production. Infrared canopy temperatures and physiological and phenological measurements were made on differentially irrigated corn throughout the 1978 growing season. Irrigation treatments were designed to evaluate the effects of moisture stress on these measurements. The soil type in the experiment area is Valentine fine sand (Typic Ustipsamment). The effect of moisture stress on vegetative growth was demonstrated by an average height difference of 50 cm between fully irrigated and nonirrigated plants. There was a tendency for plants which had been subjected to moisture stress during the grain filling stage to mature faster than plants fully irrigated during that period. Yield reductions were greatest when stress occurred during the pollination or grain filling periods. Canopy temperature increases between the onset of tasseling and the end of grain fill were related to reduced yields. Five crop temperature indices were tested for their relationship to phenological stage of growth. Three were highly correlated, one had a low correlation, and one was not correlated with phenological development.