PGR Effects on Root Growth

Our objective was to evaluate the effect of Concise (uniconazole) applications as sprays, substrate drenches and liner soaks on the shoot and root growth of herbaceous perennial plants.

Crops tested included: Hemerocallis ‘Pink Song’, Penstemon digitalis ‘Husker Red’, Phlox paniculata ‘David’, and Lobelia cardinalis.

Concise applications included: liner soaks (2 min) the before potting; foliar sprays at label recommended volume of 1 gallon per 200 square feet; or substrate drench applied at 2 fluid ounces per quart plastic pot. Sprays and drenches were applied about 2 weeks after potting.

Plants were harvested weekly for shoot and root dry weights and the root to shoot dry weight ratio was calculated. Higher root:shoot ratios have been correlated with faster plant establishment in the field.

The video shows results in photo and table forms. In summary, growth regulators often reduce root dry in proportion to the amount of shoot dry weight reduction and therefore, maintain a similar, or higher, root:shoot ratio as compared to untreated plants. Stunted plants will have stunted roots.

Joyce Latimer is an Extension Specialist for Greenhouse Crops at Virginia Tech in Blacksburg, Virginia. Joyce has been evaluating plant growth regulators (PGRs) on herbaceous perennials for over 25 years. Her passion is improving plant quality and ease of production for producers while improving the quality of these plants for the home garden.