Optimum time for evaluation of heat and drought tolerance traits in bread wheat genotypes

Mohtasham Mohammadi, Rahmatollah Karimizadeh, Peyman Sharifi

Abstract


Abstract

 

To improve wheat’s adaptation for heat and drought tolerance, increasing the effectiveness of important physiological traits and genetic diversity is needed. The difficulty of selecting for improved adaptation to abiotic stresses makes the use of indirect measures attractive to plant breeders. In this study, the measurements of canopy temperature and leaf chlorophyll content were performed three in times: before, during and post anthesis stages on fifty bread wheat genotypes at Gachsaran Agricultural Research Station in 2011-2012. Canopy temperature showed strong and reliable association with yield under drought and heat stress at three stages, particularly in grain filling stage (R2=0.645, P<0.001). High association of LCC was observed with grain yield during anthesis (R2=0.418, P<0.001), grain filling stages (R2=0.326, P<0.001), and moderate relationships before anthesis (R2=0.234, P<0.01). Maintaining of high thousand-kernel weight despite heat and drought stress was accompanied by a high level of grain yield and leaf chlorophyll content under cooler canopy temperature. These results can provide an estimate of difficult-to-measure traits such as soil moisture availability and may provide clues to help identify alternatives for breeders to further increase yield.


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