Articles
SEED COATS AS PLANT GROWTH REGULATOR CARRIERS IN BEDDING PLANT PRODUCTION
Article number
504_9
Pages
93 – 98
Language
Abstract
Bedding plants and many vegetable crops are usually started by seed in plug trays.
Some crops, like marigold (Tagetes spp.), tend to stretch very early after germination especially if grown in low light environments.
By the time the growers apply growth regulators (PGRs), the stretching of the hypocotyl has already occurred and sprays are ineffective.
It was hypothesized that some seeds have coats that are relatively impermeable to PGRs.
These impermeable coats might serve as PGR carriers, delivering the chemical into the growing medium of the plug cell.
To test this hypothesis, seeds of marigold (Tagetes patula)‘Bonanza Gold’ and geranium (Pelargonium spp.)‘Cherry Orbit’ were soaked for 6, 16, and 24 h in paclobutrazol solutions of 0, 500, and 1000 ppm.
After imbibition, seeds were dried for 24 h prior to sowing in plugs.
Seedling height and percent emergence were measured 16, 26, and 36 d after sowing.
Increasing concentrations (1000 ppm) of paclobutrazol and time of imbibition produced shorter seedlings but also reduced emergence of geranium, and the plant growth inhibition appears to persist too long.
Marigold seedling heights measured 36 d after sowing were 8.5, 8.6, and 8.6 cm when imbibed in water for 6, 16, and 24 h, respectively.
When PGR was used at 500 ppm, seedling heights were 6.5, 6.1, and 6.2 cm, respectively.
Similar or even greater reductions in heights were observed for geranium.
These preliminary results indicate that this method of PGR application (especially the 6 or 16 h soak in 500 ppm paclobutrazol) may be feasible and could benefit plug growers of marigold and other crops prone to stretching (Cosmos spp.). Chemical name used: (±)-(R*,R*)-
-[(4-chlorophenyl)methyl]- 
-(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Some crops, like marigold (Tagetes spp.), tend to stretch very early after germination especially if grown in low light environments.
By the time the growers apply growth regulators (PGRs), the stretching of the hypocotyl has already occurred and sprays are ineffective.
It was hypothesized that some seeds have coats that are relatively impermeable to PGRs.
These impermeable coats might serve as PGR carriers, delivering the chemical into the growing medium of the plug cell.
To test this hypothesis, seeds of marigold (Tagetes patula)‘Bonanza Gold’ and geranium (Pelargonium spp.)‘Cherry Orbit’ were soaked for 6, 16, and 24 h in paclobutrazol solutions of 0, 500, and 1000 ppm.
After imbibition, seeds were dried for 24 h prior to sowing in plugs.
Seedling height and percent emergence were measured 16, 26, and 36 d after sowing.
Increasing concentrations (1000 ppm) of paclobutrazol and time of imbibition produced shorter seedlings but also reduced emergence of geranium, and the plant growth inhibition appears to persist too long.
Marigold seedling heights measured 36 d after sowing were 8.5, 8.6, and 8.6 cm when imbibed in water for 6, 16, and 24 h, respectively.
When PGR was used at 500 ppm, seedling heights were 6.5, 6.1, and 6.2 cm, respectively.
Similar or even greater reductions in heights were observed for geranium.
These preliminary results indicate that this method of PGR application (especially the 6 or 16 h soak in 500 ppm paclobutrazol) may be feasible and could benefit plug growers of marigold and other crops prone to stretching (Cosmos spp.). Chemical name used: (±)-(R*,R*)-
-[(4-chlorophenyl)methyl]- -(1,1-dimethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).
Authors
C.C. Pasian, M.A. Bennett
Keywords
marigold, geranium, Tagetes patula, Pelargonium spp., paclobutrazol
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