By Laura Chapin, Juan Quijia Pillajo, and Michelle Jones, Department of Horticulture and Crop Science, The Ohio State University, Wooster
Sustainability and quality remain top priorities for both cut flower growers and consumers. Recent research at The Ohio State University funded by American Floral Endowment focuses on the use of biostimulants to improve the growth, quality, time-to-harvest, and vase life of cut flowers while reducing the need for conventional fertilizers. These promising results may provide growers with effective alternatives to traditional chemical inputs that still support high-quality crops.
Background
Cut flowers are cultivated in various environments, ranging from open fields to greenhouses, hoop houses, high tunnels, and other shade structures. More than 100 species of specialty cut flowers (which includes species other than roses, carnations, and chrysanthemums) and cut foliage are grown by large and small growers worldwide. Many of these growers are increasingly interested in biological and sustainable alternatives to conventional chemicals for both production and postharvest treatment of cut flowers.
The production of cut flowers, whether in the field or greenhouses, involves considerable chemical inputs, including pesticides and fertilizers, to produce high-quality crops and expedite the time to harvest. However, a low percentage of the applied fertilizer nutrients are utilized by the plant, as these nutrients quickly become unavailable due to adsorption to charged soil or potting substrate particles or through precipitation with metals. Nutrient deficiencies can lead to symptoms that negatively affect the appearance and quality of the foliage and flowers on a cut stem and reduce the cut flowers’ vase life for consumers. Additionally, fertilizer nutrients not taken up by the plant can leach from containers and fields, contributing to surface and groundwater pollution.
Biostimulants containing microbial inoculants and/or humic substances can play a role in reducing nutrient leaching and environmental contamination caused by excess fertilizer.
Biostimulants containing microbial inoculants and/or humic substances can play a role in reducing nutrient leaching and environmental contamination caused by excess fertilizer. Microbial inoculants can enhance the availability and uptake of essential nutrients by plants. Humic substances, such as humic and fulvic acids — extracted from soil and other organic matter — promote plant growth by increasing nutrient availability and uptake.
Reducing fertilizer inputs and nutrient losses is crucial for both large and small growers, as it lowers production costs and supports sustainability goals. This research aims to evaluate the use of biostimulants to improve the quality and vase life of cut flowers while reducing fertilizer inputs.
Biostimulant Effects on Cut Snapdragons Grown With Minimal Fertility
Microbial and non-microbial biostimulants are used to improve cut flowers’ production characteristics and post-production vase life. We used snapdragons grown under extremely low-fertilizer conditions to see if adding the biostimulants enhanced plant growth without the need for high levels of conventional fertilizers. The effects on vase life were evaluated.
Table 1. Treatment list for experiment 1. The product, source of the product, active ingredient, application rate, and method are listed.
Treatment
Product, Active Ingredient, Company
Rate
Application method and timing
1
Untreated control
2
LALRISE VITA, Lallemand, Bacillus velezensis
0.25g per plant
Drench at transplant and one month post-transplant
3
LALRISE Boost, Lallemand, Delftia acidovorans
32 fl. oz./400 gal
Drench at transplant and mid-point (week 4)
4
16 fl. oz./400 gal
Foliar spray to glisten at transplant and mid-point (week 4)
5
RSSI, BioWorks, Trichodema fungi
6 oz./100 gal
Drench at transplant
6
Cease, BioWorks, Bacillus amyloliquefaciens
6 qt./100 gal
Drench weekly
7
Continuum, Impello Bio, 4 bacteria species
1 mL/gal
8
MicroMate, HumaGro, Humic and fulvic acids
40g/gal
Snapdragon Antirrhinum majus ‘Chantilly Light Salmon’ were grown from seed. There were seven biostimulant treatments and an untreated control treatment (Table 1). Each treatment included 24 plants, and 12 of the plants from each treatment were used to evaluate the vase life of the first flower in floral preservative. All plants were grown at a low fertilizer rate (25 ppm N from 20-3-19 Jack’s Professional Petunia FeED, JR Peters, Inc.) to determine if biostimulants could promote growth and produce high-quality cut flowers with lower fertilizer inputs. Growth promotion was assessed by measuring plant height. The time to flower was recorded, and cut flower longevity was determined using a vase solution of floral preservative. The number of days until half of the open flowers wilted or the flower spike exhibited a bent neck was recorded.
Three of the biostimulant products had significant growth-promoting effects in snapdragons that would benefit cut flower growers. When grown at a low rate of fertilizer (25 ppm N), the control plants and those treated with the biostimulants Lalrise Boost (spray and drench, Lallemand Plant Care), R.S.S.I. (BioWorks), and Continuum (Impello Biosciences) still had very short stems at six weeks after transplant, while plant height was almost three times greater with Lalrise Vita (Lallemand Plant Care), Cease (BioWorks) and MicroMate (Huma) treatments (Figure 1A and 1D). The final stem diameter of the cut flowers was also significantly greater in Cease and MicroMate-treated snapdragons (Figure 1B). One very exciting result was the difference in the time to harvest the first flower, with snapdragon cut flowers from Lalrise Vita, Cease, and MicroMate-treated plants harvested an average of 19, 22, and 26 days before the control plants (Figure 1C). Once the cut stems were harvested and evaluated for vase life longevity, stems from plants treated with Lalrise Vita, Cease, and MicroMate had a significantly longer vase life than control plants (~3 to 5 days longer) (Table 2).
Table 2. The average vase life of snapdragon flowers from plants treated with biostimulants with cut stems held in floral preservative.
Biostimulant
Vase Life (d)
LALRISE VITA
12.3
MicroMate
11.8
Cease
11.2
Boost (Spray)
10.5
Continuum
7.7
Boost (Drench)
7.0
RSSI
6.8
Control
7.5
Effect of Biostimulant Combinations on Snapdragons Grown at Reduced Fertility
We were interested in evaluating the most promising biostimulant products from Experiment 1 under conditions where the nutrients were reduced but not so limiting. We were also interested in understanding if combining biostimulant products would have an additive beneficial effect on plant performance during greenhouse production. For the postproduction evaluation, we aimed to determine whether using water as the vase solution would yield similar results to the floral preservative used in Experiment 1.
Snapdragon Antirrhinum majus ‘Chantilly Light Salmon’ were grown from seed. Plants were fertilized with 50 ppm N from 20-3-19 Jack’s Professional Petunia FeED. Plants were treated with Cease, MicroMate, or Lalrise Vita or combinations of the three products. We adjusted the application method to increase efficiency. See Table 3 for treatment information, including rates and application methods. Plants were evaluated weekly during production, and stems were harvested for cut flower analysis. Cut stems were placed in vases with RO (reverse osmosis) water. The number of days until half of the open flowers wilted or the flower spike exhibited bent neck was recorded as the vase life.
When the snapdragons were fertilized with slightly higher rates, the differences in growth between biostimulant-treated plants and untreated plants (Control) were not as pronounced as in Experiment 1 (see Figure 2). Interestingly, however, the vase life of stems from plants treated with the biostimulants, whether individually or in combination, was longer than that of the untreated control, with snapdragons from plants treated with MicroMate, Lalrise Vita, and the combination of Cease+MicroMate lasting significantly longer than the non-treated plants (~ 3 to 4 days longer) (Table 4).
Figure 2. Snapdragon plants three weeks after transplant and beginning treatment with biostimulant products. Photos are representative plants of each treatment.
Vaselife (d)
10.0
VITA
9.4
Cease + MicroMate
9.1
Cease + VITA + MicroMate
8.4
8.0
VITA + MicroMate
Cease + VITA
7.4
5.7
Table 4. The average vase life of snapdragon flowers from plants treated with biostimulants and combinations of those biostimulants with cut stems held in RO water.
When these products (Cease, Lalrise Vita, or MicroMate) were applied to plants that were provided slightly more fertilizer, no growth promotion was observed. Interestingly, there were no additive benefits of treating with more than one biostimulant product, either. Nonetheless, we did see an improvement in the vase life of the cut flowers from the plants treated with the biostimulants when the flowers were held in water (no floral preservatives). Depending on the product, the plants treated with biostimulants had cut flowers that lasted approximately two to five days longer than an untreated plant. The highest vase life extensions were seen from plants treated with MicroMate, Lalrise Vita, or the combination of Cease+MicroMate.
Our research demonstrates that the use of bacteria-based commercial products along with humic-substance-containing products positively impacts snapdragons during greenhouse production and post-production vase life.
Impact of Research to the Industry
Our research demonstrates that the use of bacteria-based commercial products, such as Cease and Lalrise Vita, along with humic-substance-containing products like MicroMate, positively impacts snapdragons during greenhouse production and post-production vase life. Under conditions of extreme nutrient stress, these products significantly enhance the plants’ tolerance to minimal fertilizer availability, enabling sufficient growth and development of snapdragon plants. Even in less stressful nutrient environments, while plant growth remained unchanged by adding biostimulants, the treated cut stems outperformed those from untreated plants. These products exhibit many benefits, particularly in postharvest vase life, which holds great promise for producers and consumers in the cut flower industry.
The research highlights the significant impact of investigating the use of biological and sustainable alternatives on the growth and vase life of cut flowers under challenging conditions. These findings will help growers reduce chemical inputs while still producing high-quality flowers.
