Determining the effect of exogenous application of plant growth regulator controlling stem elongation on grain yield and components in wheat under Cukurova conditions

The research was carried out in the Faculty of Agriculture, Field Crops Department Research and Application area, Çukurova University during the 2020/2021 wheat growing season. In this research, bread wheat cultivars i.e. Adana-99, Empire and Halis were treated with plant growth regulator (PGR) (Chlormequat chloride) at the rate of 125 ml/ decare at tillering (Zadoks Growth Scale (ZBS) 2.2), beginning of stem elongation (ZBS 3.0), one node stem (ZBS 3.1), two nodes stem (ZBS 3.2), [ZBS 2.2 + ZBS 3.0], [ZBS 2.2 + ZBS 3.1] and [ZBS 2.2 + ZBS 3.2] stages of wheat. Application of plant growth regulator at ZBS 2.2+3.1 stage increased the number of stems per square meter by 27.3% as compared to the control. Moreover, the effect of PGR on spike length did not show any positive effect in Adana and Halis cultivars, but its application at ZBS 2.2 +3.2 stage increased the spike length of Empire cultivar by 24.5% as compared to the control. Similarly, the application of PGR at ZBS 2.2+3.2 stage in Adana-99 cultivar increased its grain yield by 20.1% as compared to the control while no significant effect was recorded in grain yield of Empire and Halis cultivars with PGR application. It is concluded that application of PGR positively affected Adana-99 cultivar while other wheat cultivars did not show any positive effect. Therefore, there is a need to determine the response of new wheat cultivars to PGR application. Key Words: Plant growth regulatore, Plant length, Grain yield, Grains per sequaremeter, Grain weigh