Evaluation of canopy temperature depression and relative water content as indicators for drought tolerance in maize (Zea mays L.) inbreds

Abstract

Drought tolerance is a complex trait involving morphological and biochemical mechanisms. Physiological changes due to moisture stress, which reflect an adaptive mechanism in genotype, are worth measuring for relative assessment of differences. Considering this, the present study was conducted to determine the effect of water stress on canopy temperature depression (CTD) and relative water content (RWC) to evaluate drought tolerance of maize inbreeds. Thirty maize inbreeds were evaluated in greenhouse experiment based on completely randomized design with three replications at two irrigation levels (wellwatered and low moisture-stressed). Inbreeds CML-470, DMR-N6, CML-415 and LM-12 had cooler canopies under drought conditions. The difference between CTD under irrigated and drought conditions was small initially (1.20) but increased progressively at 2nd week of stress imposition (1.70) and was highest at 3rd week of stress imposition (2.70) in all maize genotypes. High CTD can be used as a selection criterion to improve tolerance to drought and heat. RWC under drought conditions recorded the highest value in DMR-N6 followed by L-9 and V-335. The rate of RWC in plant with high resistance against drought was higher than others. In other words, plant having higher yields under drought stress should have high RWC. Relative water content can be said to be a good parameter suitable to screening drought-tolerant maize genotypes.