[nafex] FW: dormancy induction in strawberry

["Lon J. Rombough" <lonrom@hevanet.com>]

An interesting thread from the Smallfruit list.
----------
From: Peter Hicklenton <hicklentonp@EM.AGR.CA>
To: Multiple recipients of list SMALLFRUIT <SMALLFRUIT@BOBO.NWS.ORST.EDU>
Subject: Re: dormancy induction in strawberry
Date: Mon, Oct 15, 2001, 3:27 PM


Dormancy is indeed a complicated process in strawberry and you really do 
need to know the characteristics of the cultivar to determine the specific 
requirements for dormancy.

Working with Kent, Veestar and Bounty in Nova Scotia we have found that 
degree of chilling necessary to assure high post-storage quality is 
satisfied quite early. Full survival for these cultivars occurs when plants 
are lifted from the field in early November.  Over several years of study 
we have established that this date varies very little even though chilling 
hours until early November (below 8C) have varied between about 450 and 700 
from one season to another.

It appears that dormancy may occur in several stages: Early stage dormancy 
(sufficient to ensure high quality in plants stored at -1C or -2C for 
several months) is induced by declining photoperiods and relatively little 
chilling; deep dormancy sufficient to ensure the plants survive more severe 
winter temperatures may require exposure to extended periods of chilling, 
at lower temperatures.

In order to induce dormancy in your plants I suggest subjecting them to a 
programmed decline in daylength (i.e. changing the photoperiod to match 
natural conditions at your latitude progressively from early September to 
late October) and ensuring that they receive at least 450 hours of chilling 
temperatures (below 8C)

We routinely use a programmed photoperiod decline (in growth chambers). 
There is some good evidence that cold hardiness in plants  (especially 
conifers, but probably applies equally to deciduous species) respond to the 
rate of change of daylength rather than a particular number of 'short days' 
- so try programmed daylength.

Hope this is of some help




Peter Hicklenton
Agriculture and Agri-Food Canada
Atlantic Food and Horticulture Research Centre
32 Main Street
Kentville, Nova Scotia
Canada
B4N 1J5

Phone: 902 679 5760
Fax: 902 679-2311
Cell: 902 691 0027
E-Mail: HicklentonP@em.agr.ca

>>> Pauliina Palonen <pauliina.palonen@helsinki.fi> 10/08/01 03:02pm >>>
Hi strawberry people,

can anybody advice me concerning dormancy induction in strawberry? We
are
giving different short day treatments (photoperiod 12 h, temperature
15°C)ranging from 2 to 10 weeks to strawberry 'Korona' to induce
flowering. Following the SD treatments, plants are cold stored for 1 or
2 months at -1°C, and then forced in a greenhouse. As dormancy affects
storability of the plants, can anyone tell me, how to make these plants
dormant before subjecting them to -1°C storage? As far as I understand,
frigo plants are usually lifted from the field in the fall, and nature
takes care of dormancy in plants.

Kind regards,
Pauliina Palonen
University of Helsinki
e-mail: pauliina.palonen@helsinki.fi
i


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