Stimulation of Lateral Branching of Red Firespike Using Dikegulac Sodium, Benzyladenine, and Pinching

Abstract

<jats:p>Red firespike (<jats:italic>Odontonema strictum</jats:italic>) is an ornamental shrub with potential for use as a flowering potted plant due to its dark green foliage and attractive red flower spikes. To stimulate branching and improve quality of red firespike, foliar spray applications of dikegulac sodium (DS) and benzyladenine (BA) and hand pinching were evaluated across two seasons (Spring and Summer 2014). There were three pinching treatments: one, two, or three pinches. Plant growth regulators (PGRs) were applied at 400, 800, 1600, or 2400 ppm DS or 600, 1000, 1250, or 1750 ppm BA. Both studies included an untreated control. Red firespike treated with all concentrations of BA and 1600 and 2400 ppm DS had increased branching compared with the control, except 1000 ppm BA in Expt. 1. Pinching did not affect the number of branches. Dikegulac sodium at 1600 and 2400 ppm and all concentrations of BA resulted in shorter plants than the control. Phytotoxicity was observed in plants treated with 1600 or 2400 ppm DS. In both experiments, DS at 1600 and 2400 ppm had the least plant dry weight compared with the control. Treatment with BA at 1750 ppm resulted in greatest leaf area compared with control. Dikegulac sodium at 800 ppm increased the number of flowers compared with control. Pinching and BA did not affect number of inflorescences. All concentrations of BA and DS delayed flowering, except 1000 ppm BA. Plants treated with 800, 1600, and 2400 ppm DS had shorter inflorescences compared with control plants. Benzyladenine decreased the length of the inflorescence at high concentrations, 1250 and 1750 ppm. Pinching treatments did not affect inflorescence length.</jats:p>

Effects of Paclobutrazol and Flurprimidol on Water Stress Amelioration in Potted Red Firespike

“…Firespike is a flowering perennial in the Acanthaceae, native to the tropical and subtropical regions of Central America (Daniel, 1995). It has potential for use as a flowering potted plant because of the attractive red spikes, dark green foliage, and natural bloom time (Rezazadeh et al, 2015). Firespike is reported to be a short-day plant (Garofalo, 2002); therefore, vegetative stock plants of red firespike were maintained under long days (natural daylength plus 4-h night interruption lighting with 60-W incandescent lights from 2200 to 0200 HR) to prevent floral initiation occurring before starting the experimental treatments.…”

“…Although PGR research has been conducted on firespike (Rezazadeh et al, 2015), no studies have been published examining the effects of PGRs on drought tolerance of firespike growth and flowering. The objectives of this study are to examine the physiological and morphological responses of firespike to water stress after being treated with PBZ and flurprimidol and determine whether these PGRs increase firespike drought tolerance.…”

Floral Initiation in Red Firespike (Odontonema strictum): Effects of Photoperiod and Duration of Short Day Exposure

“…It is native to the tropical and sub-tropical regions of Central America (Daniel, 1995). The plant has potential as a flowering potted plant due to its attractive red inflorescence, dark green foliage, and natural bloom time (Rezazadeh et al,. 2015).…”

Influence of Environmental Parameters, Pinching, and Ethephon Application on Growth and Branching of Potted Stevia

“…Lateral branch production is critical for producing attractive potted plants, particularly for plants such as stevia where lateral branching is strongly inhibited during the young plant stage. Promotion of axillary meristem release from apical dominance is often achieved through shoot decapitation, or "pinching" (Larson, 1985), or by application of chemical growth regulators, including benzyladenine (Latimer and Freeborn, 2010;Rezazadeh et al, 2015), dikegulac sodium (Grossman et al, 2013;Sun et al, 2015), and ethephon (Currey and Erwin, 2012;Hayashi et al, 2001). Removal of apical buds of fieldgrown stevia plants increased branch number at harvest by 48% to 72% while foliar applications of KNO 3 and Ca(NO 3 ) 2 did not impact branch number (Pal et al, 2013).…”