Determining the rooting performance and plug extractability of Begonia (Begonia x hybrid) Vegetative Cuttings as affected by loose filling and Terra Plug bonded media made with two different types of mixes with varying physical properties.
Vijay Rapaka, Ph.D.
Corporate Grower Research & Technical Support Manager
Smithers-Oasis Company, Kent, OH, USA
Greenhouse Research Technician
Smithers-Oasis Company, Kent, OH, USA
Terra Plugs are physically bonded media manufactured using a unique horticultural-friendly technology. Terra Plugs are made from peat and coco and contain a fertilizer starter charge. Terra Plugs, unlike loose filled plugs, maintain the original air / water porosity during the whole course of propagation. Terra Plugs are available with various mix options providing various air and water holding capacities to cater to the propagation needs of wider variety of crops.
The objective of this study is to determine the rooting response, speed of rooting, and plug extractability of two Begonia cultivars ‘Mistral Red’ and ‘California Sunlight’ propagated in Terra Plugs with two different water holding capacities and compare against loose mix.
Materials and Methods
Begonia ‘Mistral Red’ and ‘California Sunlight’ were received in Kent, OH, from offshore locations on 4/19/2016. Cuttings were inserted into a 72-count Terra Plug Standard Mix, Terra Plug Dry Mix, and a loose-filled propagation mix. The two types of Terra plug mixes contained different amounts of peat and coco. On the other hand, loose-filled propagation mix contained propagation grade peat, perlite, and vermiculite. The properties of the mixes are presented below. For the first 48 hours, the mist system was turned on for 8 seconds every 8 minutes and for the remainder of the week, the misters were run between 6:00 a.m. to 8:00 p.m. Misting frequency was further reduced after the first week. By the end of second week, the mist system was totally shut down and watered as required with a hose and breaker, using complete nutrient solution with 125 ppm N. The daytime venting and heating set points were 75° F (24 ° C) and 65° F (18° C). The nighttime venting and heating set points were 70° F (21° C) and 62° F (17° C). The bottom heating on the propagation bench was set at 76° F (18° C). The propagation was conducted in a diffused light environment and the greenhouse was shaded when the PPFD was higher than 350 μmoles. m-2. Sec-1.
Rooting evaluation was conducted on Day 20 after sticking. A 0 – 5 scale was used for evaluating the rooting performance, 0 – Poor Rooting, <3 – Unacceptable, 3 – Acceptable, and 5 – Best Rooting. The rooted cuttings were also evaluated for a percentage plug release or extractability for transplanting. The data was subjected to statistical analysis, ANOVA, to evaluate the significant differences between treatments.
The following are the chemical and physical properties of the two Terra Plug Mixes:
*Parameters were determined on a cylindrical disc measuring 4 cm in height and 7.6 cm in diameter.
Results and Discussion
The rooting evaluation was conducted on Day 20 after insertion to capture the early rooting response (Fig. 1 – 4). In both cultivars, the rooting response was extremely uniform and significantly better in Terra Plug Mixes compared to loose fill. The superior rooting response in Terra Plugs can be attributed to structural stability and the resultant uncompromising air to water ratio during the whole course of propagation. No statistically significant differences were observed between the two types of Terra Plug mixes. Major differences were observed with the extractability or release of rooted cuttings. In the case of both cultivars, 100% of the cuttings rooted in Terra Plugs was extractable, whereas, a significantly low percentage of rooted cuttings were extractable in the case of loose filled mix (Fig. 1 & 3). The superior extractability of Terra Plugs can be attributed to the structural integrity of the bonded media, patented plug releasing technology, and also the improved rooting response. In general, Terra Plug rooted cuttings were 5 to 7 days ahead compared to loose fill rooted cuttings, with regard to extractability. The shoot growth was also superior when propagated in both Terra Plug mixes, compared to the loose fill.
Fig. 1: Begonia ‘Mistral Red’ rooting response and percentage of extractable plugs when cuttings were propagated in loose fill, Terra Plug Standard Mix, and Terra Plug Dry Mix. The evaluation was conducted 20 days after inserting the cuttings.
Fig. 2: Begonia ‘Mistral Red’ 20 days after inserting into loose fill, Terra Plug Standard Mix, and Terra Plug Dry Mix (from left to right) – photos showing shoot growth (top) and rooting response (bottom)
Fig. 3: Begonia ‘California Sunlight’ rooting response and percentage of extractable plugs when cuttings were propagated in loose fill, Terra Plug Standard Mix, and Terra Plug Dry Mix. Evaluation was conducted 20 days after inserting the cuttings.
Fig. 4: Begonia ‘California Sunlight’ 20 days after inserting into loose fill, Terra Plug Standard Mix, and Terra Plug Dry Mix (from left to right) – photos showing shoot growth (top) and rooting response (bottom)
The propagation of Begonias in Terra Plugs promotes faster and uniform rooting and can significantly cut down the time to transplant by 5 days or more.
Since no significant differences in rooting response were observed between Standard and Dry Terra Plug Mixes, they can be used interchangeably depending on the location, season, and greenhouse conditions.
The following is the general procedure for Propagation of Begonias in Terra Plugs:
- Saturate the Terra Plugs and place them in a disinfected propagation area
- Insert the cuttings on the same day they arrive
- Rooting hormone is generally not required for Begonias
- For the first 48 hours, mist cuttings on a regular basis or cover with a cheese cloth. Thereafter, mist between 6:00 a.m. and 8:00 p.m. as required. Do not let the cuttings over-wilt during the course of propagation
- Do not over-mist or over-water, as it results in leaching nutrients from the media
- Maintain daytime air temperature between 65° F (18° C) and 75° F (24° C) and nighttime air temperature between65°F(18°C)and72°F(22°C)
- Provide bottom heating between 72° F (22° C) and 76° F (24° C)
- Maintain pH between 5.8 and 6.2 and an EC of 1 mS/cm
- Two weeks after insertion, water with complete nutrient solution with 125 ppm N
- Propagate cuttings under diffused light with light levels around 200 μmoles. m-2. Sec-1 during the first week. Cuttings can tolerate light levels around 300 μmoles. m-2. Sec-1 by the end of second week. Cover the propagation area with shade curtains when the light levels go beyond 350 μmoles. m-2. Sec-1
- Preventive sprays combined with proper venting and water management can help control Botrytis
- Apply PGRs as required to keep cuttings compact. Pinching is recommended
- Generally, cuttings will be fully rooted and ready for transplant in 24 to 28 days after sticking
- Do not let Terra Plugs completely dry out during the course of propagation
- Follow the general transplant procedure