Articles
Comparison of the effects of root restriction and intermittent low temperature storage on bolting in Delphinium grandiflorum
Article number
1453_19
Pages
141 – 146
Language
English
Abstract
In Delphinium grandiflorum, whose flowering is promoted by high temperatures and long-day conditions, the production of high-quality cut flowers under high temperature conditions is hindered by early bolting.
Root volume restriction can effectively inhibit early bolting under high temperature conditions in D. grandiflorum, and intermittent low temperature storage (ILTS), which repeatedly alternates between refrigerator storage and growth in the greenhouse, is effective as well.
Although root restriction is easier than ILTS, because seedlings remain in the greenhouse during the entire period, its effectiveness appears to vary among cultivars.
In this study, we compared the effect of root restriction and ILTS during the same year to optimize cultivation of seedlings of two D. grandiflorum cultivars (early-season ‘F1 Morpho Grand Blue’ and mid-season ‘F1 Morpho Platinum Blue’) under high temperature conditions.
In contrast to ILTS, which resulted in a 0% early bolting rate in seedlings of both cultivars, root restriction produced different effects between cultivars.
In particular, early bolting of ‘F1 Morpho Platinum Blue’ seedlings grown in 288-hole cell trays (root zone volume of approximately 9 mL) was suppressed (0% bolting rate) compared with that of seedlings in 128-hole trays (approximately 20 mL; 10% bolting rate). In contrast, root restriction did not completely suppress early bolting of ‘F1 Morpho Grand Blue’, whose early bolting rates in 288 and 128 holes were 62 and 45%, respectively.
No significant difference in cut flower quality was observed among treatments.
The effectiveness of root restriction may have been influenced by differences in earliness between cultivars; in contrast, that of ILTS was not strongly impacted by earliness because refrigeration reduced plant growth.
Our findings suggest that ILTS is suitable for early-season cultivars, whereas root restriction is more appropriate for mid-season ones.
Root volume restriction can effectively inhibit early bolting under high temperature conditions in D. grandiflorum, and intermittent low temperature storage (ILTS), which repeatedly alternates between refrigerator storage and growth in the greenhouse, is effective as well.
Although root restriction is easier than ILTS, because seedlings remain in the greenhouse during the entire period, its effectiveness appears to vary among cultivars.
In this study, we compared the effect of root restriction and ILTS during the same year to optimize cultivation of seedlings of two D. grandiflorum cultivars (early-season ‘F1 Morpho Grand Blue’ and mid-season ‘F1 Morpho Platinum Blue’) under high temperature conditions.
In contrast to ILTS, which resulted in a 0% early bolting rate in seedlings of both cultivars, root restriction produced different effects between cultivars.
In particular, early bolting of ‘F1 Morpho Platinum Blue’ seedlings grown in 288-hole cell trays (root zone volume of approximately 9 mL) was suppressed (0% bolting rate) compared with that of seedlings in 128-hole trays (approximately 20 mL; 10% bolting rate). In contrast, root restriction did not completely suppress early bolting of ‘F1 Morpho Grand Blue’, whose early bolting rates in 288 and 128 holes were 62 and 45%, respectively.
No significant difference in cut flower quality was observed among treatments.
The effectiveness of root restriction may have been influenced by differences in earliness between cultivars; in contrast, that of ILTS was not strongly impacted by earliness because refrigeration reduced plant growth.
Our findings suggest that ILTS is suitable for early-season cultivars, whereas root restriction is more appropriate for mid-season ones.
Authors
M. Kawai, K. Motoki, M. Hikawa-Endo, K. Yasuba, T. Goto
Keywords
cell tray, cold storage, cut flower quality, high temperature, seedling
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