July 2015 issue of the Cornell Flower Bulb Research Program Research Newsletter:
Tulips were grown in the greenhouse, and treated with Collate near first bud color. After treatment, they were placed in a dark cooler for 2 weeks at 2C. After this cold period, they were put into a low light growth chamber at 20C and 12 hours day and 12 hours night, to simulate an indoor environment. Plants sprayed with Collate (ethephon) were short and compact, and had very short top internode growth.
Read the whole article. Starts on page 5.