Grain Yield in Corn Hybrids Exposed to Water Stress at Different Growth Stages and the Use Thermal Imaging.

The aim of this study was to evaluate decreases in grain yield and other yield components of two corn (Zea mays L.) hybrids exposed to water stress at different development stages, and their association with thermal imaging and soil moisture. An irrigated pot experiment was conducted at FCA-UNNE (Corrientes, Argentina) during 2016, under a polyethylene film roof of 100 microns, and without nutrient restrictions. A randomized design with one plant per pot and three replications was used. (i) Two commercial hybrids (Te= temperate, and Tx= tropical x temperate) were grown with (ii) five water treatments (T0= full-irrigated control; and withholding irrigation during T1= 20-10 days presilking, T2= 10 days presilking, T3= 10 days postsilking, and T4= 10-20 days postsilking). Thermal imaging (FLIRC2) and soil moisture measurements (Decagon 5TM) were taken daily. Results showed that grain yield (relative % to the control treatment) was lower in Te (63.1, 62.5, 64.9 and 80.8% for T1, T2, T3 and T4 respectively) than in Tx (83.7, 91.5, 39, 3 and 97.7%, respectively), mainly in presilking. Thermal imaging detected soil water content variations, especially in T3 and in Tx. A negative association was found between soil moisture and leaf temperature in the most affected treatment, which increased with the passing days (R2=0.2817 on day 6, and 0.7611 on day 12 of drought) for both hybrids. The use of thermal imaging proved to be a reliable method for determining soil moisture content that agronomists can apply to evaluate water stress in corn.