Shortlongday plants SLDP

Alopecurus pratensis (LD promotes flower development at >12°C, little effect of daylength at 6°C)

Bromis inermis

Dactylis glome rata strain si 43 Scabiosa succisa Symphandra hoffmanni L

6a. SLDP require or accelerated by vernalisation Apium graveolens (requires SD during vernalisation)

6b. SLDP; vernalisation substitutes at least partly for the SD effect and, after low temperature, plants respond as LDP

Campanula medium Coreopsis grandiflora Dactylis glomerata

Echeveria harmsii; setosa (at 15-20°C) Hordeum bulbosum

Poa annua (some strains, +9) alpigena; arctica; pratensis; palustris Trifolium repens

Iberis intermedia Durandii, winter strains of Avena, Lolium, Hordeum, Secala and Triticum and Festuca could also be placed here instead of 3c or 4c as, without LT, they respond as SLDP

7. Intermediate day plants (flower only in, or are accelerated by intermediate daylengths)

Aristeda contorta Bouteloua curtipendula (+3) Capsicum annuum

Cyperus esculentus; rotundus (at 32°C) Mikania scandens L Ocimum basilicum L Paspalum dilatatum (or ?3) Plectranthus fruticosus L Saccharum spontaneum

Solidago canadensis (1 for initiation but very SD induce rapid onset of dormancy)

Tephrosia Candida H, L (or ?5)

Trifolium usambarense (at >21°C, 1 at 10-21°C)

8. Ambiphotoperiodic plants (inhibited by intermediate daylengths)

Chenopodium rubrum ecotype 62°46 N (at 25°C; 2 at lower temperatures) Hibiscus sabdariffa Madia elegans L

Phaseolus vulgaris (some cvs, +2, 9) Setaria verticillata

9. Day-neutral plants (flower at about the same time in all daylengths)

Achimenes hybrids Allium cepa

Anigozanthos pulcherrimus; rufus Aphelandra squarrosa Arachis hypogaea (? +7) Asclepias tuberosa Blepharis linearifolia

Browallia speciosa Brunfelsia pauciflora Carica papaya Cestrum elegans E Chenopodium foetidum Coleus blumei Princeton strain Cornus florida

Cryptomeria japónica (SD increase <J, LD increase 9)

Cupressus arizonica (SD increase <J, LD increase 9)

Cyclamen persicum

Eucharis grandiflora

Fagopyrum esculentum; tataricum A,S

Fragaria X ananassa (everbearing); vesca semperflorens

Gomphrina globosa S

Gossypium hirsutum (+1, primitive types)

Guzmania monostachys

Hibiscus rosa-sinensis

Hippeastrum hybrids

Ilex aquifolium A

Lemna aequinoctialis (paucicostata, K type, strain 351)

Litchi chinensis

Lycopersicon esculentum

Malus sylvestris (apple)

Morus nigra

Olea europaea

Ornithogalum arabicum

Pelargonium X hortorum

Pinus spp.

Pistia stratioides

Pisum sativum (early flowering strains) Poa annua (+6b)

Prunus amygdalus (peach, apricot)

Pseudotsuga spp

Pyrus communis (pear)

Ranunculus ficaria; penicillatus var calcareus

Rhododendron obtusum P

Saintpaulia ionantha

Schlumbergera truncata (at 10°C, 2 at higher temperatures)

Scrophularia peregrina; arguta

Senecio cruentus (4 for development); vulgaris C

Simmondsia chinensis (jojoba)

Solanum melongena (?4, small LD response)

Spiraea cantonensis

Spirodela polyrrhiza

Strelitzia reginae

Streptocarpus x hybridus

Thuja plicata (SD increase <J, LD increase 9)

Viburnum burkwoodii; carlesii

Vicia faba (very early flowering genotypes, +4, 4a)

Vitis vinifera

Vriesea splendens

Zantedeschia aethiopica

364 APPENDIX I photoperiodic classification

9a. DNP requiring or accelerated by vernalisation

Allium cepa (LD promotes emergence) Agrimonia eupatoria C Apium graveolens (see 2a)

Brassica spp. (brussels sprout, cabbage, cauliflower, kale, kohl rabi) Cardamine amara C Daucus carota

Dianthus barbatus (very slight acceleration in LD)

Dichondra repens (micrantha)

Digitalis lanata

Draba aizoides; hispanica C

Eryngium variifolium C

Euphorbia lathyris C

Geum bulgaricum; canadense; x intermedium; macrophyllum C; urbanum

Lunaria annua (biennial strain, or ?4b)

Melandrium rubrum

Nerine flexuosa

Pastinaca sativa

Pyrethrum cinerariifolium C

Rheum rhaponticum

Saxifraga rotundifolia C

Scrophularia umbrosa (syn alata)', vernalis C

Senecio vulgaris C

Setaria viridis

Silene dioica\ italica\ nutans Thlaspi perfoliatum K

This appendix was compiled mainly from Halevy (1985). Entries from other sources are indicated as follows:

A, Altman and Dittmer (1964, 1973)

C, Chouard (1960)

K, Hajkova and Krekule (1972)

S, Salisbury (1963b).

The photoperiodic categories used in Vince-Prue 1975 have been much simplified since it is becoming more and more apparent that photoperiodic categories are not fixed but can be considerably modified by temperature and other environmental variables such as irradiance, as well as with age. A few of the interactions with temperature are indicated, especially where low-temperature vernalisation is required or substitutes for daylength. In general, plants have only been included where the photoperiodic response group is based on experiments with a range of daylength; if deduced from field studies, they have been included only when the category is reasonably certain. Thus many plants for which a daylength response group has been proposed on the basis of field observations have been omitted. It is not always possible on the basis of the available evidence to determine if a response is obligate or facultative; allocation to the absolute classification in this table means only that flowering is usually delayed for several months in non-inductive conditions.

Crop plants often show a range of behaviour with genotype; where possible, plants have been listed in the most commonly found response groups, with other categories indicated in brackets; e.g. (+9) means that some genotypes are day-neutral. Early cultivars often show a response closer to the wild type, while modern genotypes tend towards less stringent daylength requirements.

Only anthesis has been recorded in many examples and, therefore, effects on initiation may be confounded with effects on development. Where possible, plants have been allocated to response groups on the basis of initiation; specific effects on development are given where these are known.

+1 -1

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