Leaf and Canopy Temperatures of Pearl Millet Genotypes under Irrigated and Nonirrigated Conditions1

Abstract

AbstractIt has been reported from previous research that leaf and canopy temperatures correlate with the level of water stress in a plant. If genotypes of a given species differ in their response to water stress, then leaf and canopy temperatures could serve as indices of their drought resistance. To test this hypothesis, 10 pearl millet (Penniserum americanum (L.) Leeke) genotypes differing in plant morphology were grown on a Eudora silt loam soil (fine silty, mixed, mesic, Pachic Haplustoll) under both irrigated and nonirrigated conditions. Leaf temperature (Tl), canopy temperature (Tc), canopy minus air temperature (Tc – Ta), leaf‐water potential (Ψl), leaf‐diffusion resistance (LDR), water use (WU), and crop yields were observed in both irrigated and nonirrigated treatments. Significant differences (P<0.05) were found in the grain yield, Tc, and Tc – Ta of genotypes, only in the irrigated treatment. Grain yield was negatively and significantly correlated with average afternoon Tc(r = −0.81) and average afternoon Tc – Ta(r = −0.78). Grain yield ratio (nonirrigated grain yield/irrigated grain yield) was positively and significantly correlated with average afternoon Tl(r = 0.64), average afternoon Tc(r = 0.64), and average afternoon Tc – Ta(r = 0.75). In the nonirrigated treatment, however, correlations of grain yield and grain yield ratio with various stress indices were nonsignificant. Average afternoon Tc and Tc – Ta was significantly correlated with average afternoon LDR only in the irrigated treatment. This study suggests that average afternoon Tc and Tc – Ta as observed in a nonstressed environment with an infrared thermometer could effectively be used as a technique to screen millet genotypes for their grain yield and grain‐yield stability (nonirrigated grain yield/irrigated grain yield).