Regulation of curd initiation in the summer cauliflower
Factors regulating curd initiation in the summer cauliflower were examined with special attention given to responses to change in environment. Low temperature treatments of four weeks at 5°C accelerated curd initiation, reducing the number of leaves initiated before the curd. A reduction in vegetati...
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| Format: | Thesis |
| Language: | English |
| Published: |
1988
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| Online Access: | http://eprints.nottingham.ac.uk/27674/ https://eprints.nottingham.ac.uk/27674/1/384336.pdf |
| Summary: | Factors regulating curd initiation in the summer cauliflower were examined with special attention given to responses to change in environment. Low temperature treatments of four weeks at 5°C accelerated curd initiation, reducing the number of leaves initiated before the curd. A reduction in vegetative growth was associated with earlier curd initiation. The extent of the low temperature effect was dependent on genotype, temperature, treatment duration and the plant's stage of development when low temperature treatments commenced. A distinct juvenile phase was observed when plants were incompetent to perceive chilling as a vernalization stimulus. Phase transition from the juvenile to the mature, competent form was associated with the initiation of a specific number of leaves. These were 14 and 18 leaves for cvs Perfection and White Fox respectively, leaf number being higher in the later season cultivar. The duration of phase change itself was short, lasting approximately two plastochrons. Increase in leaf initiation rate was associated with phase transition. Rate of leaf initiation increased with increasing temperature. Duration of the juvenile phase, measured chronologically, was therefore shorter at higher temperatures. Shoot dry weight was linearly related to leaf number in plants examined here; this characteristic would also be a stable marker for phase transition. Chilling imbibed seed proved ineffective in accelerating curd initiation. Reduction in total irradiance receipt delayed curd initiation in plants grown under warm conditions. Associated with this delay were reductions in rate of leaf initiation and stem dry weight increment. Photoperiods of 16 h following sub-optimal vernalization allowed faster curd initiation than photoperiods of 8 hand 24 h. A minimum stem dry weight at curd visibility was achieved under this regime. Reciprocal of leaf number subtending the curd, denoting the rate of progress towards curd initiation, was shown to be linearly related to temperature under controlled environment ... |
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