2017 ASHS Annual Conference

Deficit irrigation can be used to reduce irrigation volume and control plant growth. Most research using deficit irrigation has focused on the overall plant growth and has not evaluated the impact of reduced irrigation on flowering. Quantifying floral development of plants grown with deficit irrigation is important as visual appearance and bloom quality impacts the salability of flowering plants. The aim of this research was to measure floral development of Salvia nemorosa L.  ‘Ostfrieland’ (East Friesland) in response to deficit irrigation applied via maintenance of a low substrate water content. A soil-moisture sensor automated irrigation system was used to apply irrigation treatments at different times during the production cycle. Plants were grown with four irrigation treatments: continuous low and high substrate water contents (0.20 or 0.38 L·L^–1) and two alternating treatments to apply deficit irrigation for either the first two weeks (0.20 L·L^–1 followed by 0.38 L·L^–1, LH treatment) or final four weeks (0.38 L·L^–1 followed by 0.20 L·L^–1, HL treatment) of the six week study. Sensor readings were taken and recorded every hour and irrigation was applied for 60 seconds when sensor readings were below the programmed setpoints. Plant height, number of flowers, and branching of floral stems were measured biweekly. Average flower stem length, longest flower stem, and shoot dry weight were measured at the conclusion of the experiment. Final number of floral stems and longest floral stem was not significant. Average plant height (489.6, 488.5, 451.3, and 406.8 mm for the LH, high, HL, and low treatments, respectively) and average length of floral stems (448.0, 429.9, 393.1, and 348.6 mm for the LH, high, HL, and low treatments, respectively) were significant. Number of branched floral stems, compactness and shoot dry weight were also significant. Visually plants in the LH treatment had an open, floppy habit at the conclusion of the experiment that would impact sales in a retail setting. Plants in the low control treatment were smaller, but considered salable. Daily irrigation count and total irrigation volume were lower for the treatments HL and low treatments than the LH and high treatments.