Effects of Plant Growth Regulators on Growth and Reproduction of Humulus lupulus
Traditionally, in the US, hops are grown in the field in northern latitudes without the use of plant growth regulators (PGR). This research was to find out if the use of PGR could sufficiently reduce the height of hop vines to allow them to be grown in a greenhouse and produce similar flower yield of those grown in the field at northern latitudes. The hop cultivar Cascade was chosen for this study after it was compared in a preliminary trial with 'Perle', 'Fuggle' and 'Magnum'. In that initial trial, 'Cascade' produced the highest yield and appeared to be better adapted for growth under greenhouse environments using hydroponics. Of the four PGR's (Sumagic, Cycocel, B-9, and A-Rest) evaluated, only Sumagic had any effect on reducing vine length. Treatments that yielded the highest reduction in vine length (325 cm) was Treatment #1 (5 ppm) of Sumagic. Application of Sumagic slightly affected the average wet flower weight from 259, 226.5, 324, 284, and 282.5 grams from 5ppm to 0ppm, respectively. The first internode measurements had average lengths of 3.25, 7.75, 12.25, 14.5, and 18.25 centimeters 5.0 ppm to 0.0 ppm, respectively. Each Treatment yielded results that were significantly different from each other. All vine length reductions were significantly different. Treatments #1 (5 ppm), #2 (2.50 ppm), and #4 (0 .62 ppm) yielded had average lengths of 421.06, 417.44, and 430.00 centimeters respectively. Wet flower yield were 104.88, 251.50, 217.75, 257.38, and 213.75 grams from 5ppm to 0ppm, respectively. The first internode measurements produced average lengths of 3.62, 6.88, 10.50, 15.19, and 18.44 centimeters from 5.0 ppm to lowest 0.0 ppm of PGR. Results of the second experiment yielded similar results for vine reduction and flower yield.
Newton Chad Rowland,
"Effects of Plant Growth Regulators on Growth and Reproduction of Humulus lupulus"
ETD Collection for Tennessee State University.