Association of canopy temperature depression with yield and morphological traits of spring soft wheat under Siberian conditions

The method of infrared thermometry is widely used in the world to diagnose drought tolerance of crops. However, in Russia the measurement of Canopy temperature depression (CTD) has not yet been carried out. The aim of the study was to measure CTD and consider the possibility of using this trait to assess spring soft wheat varieties when growing in the Altai Territory (South-Western Siberia of Russia). The studies were conducted in 2017 and 2018 using 36 varieties of spring soft wheat in the vegetative stage and 14 varieties in the grain filling stage, respectively. Significant differences between the varieties for CTD values in both years of the study were established. There was no reliable correlation between CTD and most of agronomic traits of the studied genotypes. CTD also did not significantly correlate with grain yields in neither 2017 nor 2018 (r=0.31; r=-0.14, respectively). However, we found a reliable correlation of the trait with the plant height in 2018 (r=0.83). This may explain the wide distribution of tall varieties in Siberia. If drought occurs before heading, when the plants are oppressed and do not close the canopy, the use of infrared thermometry is difficult throughout the growing season, since the measurement error increases significantly. In Siberia, this method is suitable only in the conditions of mild droughts or when using the steam precursor in wheat cultivation.