Plant Soil Environ., 2011, 57(8):357-363 | DOI: 10.17221/75/2011-PSE

Management of sunflower stand height using growth regulators

T. Spitzer¹, P. Matušinský¹, Z. Klemová¹, J. Kazda²

¹ Agrotest fyto, Ltd., Kroměříž, Czech Republic

² Department of Plant Protection, Faculty of Agrobiology, Food and Natural Resource, Czech University of Life Sciences Prague, Prague, Czech Republic

Influence of growth regulators chlormequat chloride, ethephon, trinexapac-ethyl, and a combination of chlormequat chloride and ethephon on decreasing sunflower height was examined in the years 2006-2009. Height was reduced by as much as 63 cm by double application of chlormequat chloride (915 g/ha) + ethephon (465 g/ha) at early and later growth stage (BBCH 32 and 50). Trinexapac-ethyl (375 g/ha) did not affect the height. One-time application of chlormequat chloride (1440-2160 g/ha), chlormequat chloride (458 g/ha) + ethephon (233 g/ha) (BBCH 30 or 50), or ethephon (480 g/ha) (BBCH 30) was sufficient for a ca 30 cm reduction during flowering, but this effect did not last until harvest. With double application (BBCH 30 and 50), reduction lasted until harvest. For ethephon (480 g/ha), application at BBCH 50 reduced height by as much as 35 cm and lasted until harvest. Combining a lower rate of ethephon with ammonium sulfate was effectively equivalent to using a full rate. Flower head diameter at maturity showed no significant negative influence compared to the control. In 2008 and 2009, a delay in flowering onset was observed after applying growth regulators.

Keywords: growth inhibition; chlormequat chloride; ethephon; trinexapac-ethyl

Published: August 31, 2011  Show citation