The effects of chlormequat chloride and ethephon on agronomic and quality characteristics of South African irrigated wheat

Plant growth regulators (PGR's) that reduce lodging have not been evaluated on commercial wheat cultivars under local irrigated conditions. The objective of this study was to assess the effects of PGR's on agronomic and quality parameters of three wheat cultivars under irrigation in the field. A control (water) and two PGR's, chlormequat chloride and ethephon, were applied either individually or in combination with each other at the tillering, stem elongation or the flag leaf stages of growth to the cultivars Kariega (lodging susceptible), Olifants (lodging tolerant) and SST 876 (lodging tolerant) at Vaalharts and Bethlehem. The 4 × 32 factorial treatment combinations were tested in a RCBD with four replications in the 2003, 2004, and 2005 seasons. Ethephon and the PGR combination were most effective at reducing plant height and lodging when applied to Kariega at the flag leaf stage. Grain yields were either improved or reduced depending on the presence or absence of lodging, the PGR applied, and the time of application (TOA). Significant PGR X TOA interactions were observed for hectoliter mass, protein content, and falling number. The results suggest that PGR's should be recommended on specific cultivars in environments conducive to lodging.