Benzyladenine Application Increased Basal Shoot Production in Four Echinacea Cultivars

The objective of this study was to quantify the influence of benzyladenine (BA) application on basal shoot production in ‘After Midnight’, ‘Harvest Moon’, ‘Sunrise’, and ‘Magnus’ echinacea.  Liners of the four echinacea cultivars were transplanted in 15-cm containers in a peat-based medium.  Plants received a single foliar application of BA at 0, 300, 600, or 900 mg·L⁻¹ at transplant or 3 weeks thereafter.  Ten plants per treatment were arbitrarily placed on greenhouse benches and grown in a polycarbonate greenhouse under a 16-h photoperiod.  The mean daily temperature and daily light integral during the experiment were 24.1±0.6 °C and 10.6±0.6 mol·m⁻²·d⁻¹, respectively.  The number of basal shoots was counted at 0, 3, 6, and 9 weeks after treatment (WAT) and percentage increase in basal shoots at 3-week intervals was computed.  Data were analyzed as repeated measurements in SAS’s PROC MIXED and pair-wise treatment comparisons were made using LSD at P ≤ 0.05.  Compared with the controls, the BA treatments resulted in significantly higher percentage increase in basal shoots at 3 WAT, with no subsequent increase at 6 or 9 WAT.  BA application at transplant generally elicited a greater percentage increase in basal shoots compared with BA application 3 weeks after transplant.  In ‘After Midnight’, percentage increase in basal shoots was the greatest when BA was applied at 600 mg·L⁻¹ whereas; all the tested BA rates were similarly effective in increasing basal shoot production in the other three cultivars.  Compared with the controls, ‘After Midnight’, ‘Harvest Moon’, ‘Sunrise’, and ‘Magnus’ treated with BA at 600 mg·L⁻¹ at transplant had 200%, 62%, 135%, and 148% more basal shoots, respectively.  Based on these results, we recommend a BA application at 600 mg·L⁻¹ at transplant to increase basal shoot production in echinacea.