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Apple Delight Rhubarb Plant

The Rhubarb development project is needed for increasing production demand, for a better understanding of customer requirements in terms of stalks colour, uniformity and yield, to satisfy the growers demand for improved plant material and growing techniques.

Rhubarb Development

Identifying how popular Rhubarb has become in Britain in recent years, (the Rhubarb business has grown from being worth £15 million in 2007, to £23 million in 2010) Hargreaves Plants Ltd decided to invest in research to develop new varieties of Rhubarb to meet demand and capitalise on this lucrative product.

Easter Agri Tech

Hargreaves Plants Ltd applied to the Eastern Agri-Tech Growth Initiative for a grant of £47,000, to grow new varieties of rhubarb that will improve the marketability of the product in terms of aesthetic appearance, whilst also improving the production and quality of rhubarb varieties to suit both consumer and grower demands.

Vision

To develop new varieties of Rhubarb that will not only be more flavoursome and look more appealing to consumers, but also be a better quality plant and be more cost-effective for growers to produce.

Results

Garth Baxter Hargreaves Plants Rhubarb Development Garth Baxter, Managing Director of Hargreaves Plants Ltd, said: “We are absolutely delighted to have been awarded this grant. Hargreaves Plants have been involved in the supply chain of Rhubarb plants for the last few years, but it is evident the industry is crying out for some product development.

“There has been no formal research done on rhubarb since 1990’s and rhubarb has gained tremendous popularity since then. This grant application will add benefit to all sectors involved in the ever expanding Rhubarb industry.”

Rhubarb Development Project
This project is needed for increasing production demand, for a better understanding of customer requirements in terms of stalks colour, uniformity and yield, to satisfy the growers demand for improved plant material and growing techniques.

General information
Rhubarb has been consumed in the UK for over almost 200 years and is well known for its health benefits, being used in the beginning as a medicine and not as a vegetable. It is native to Siberia and has been used as a medicinal plant in Asia for over 5,000 years. Introduced by European settlers in the 17^th Century it has been more commonly known as a “pie plant”.
Rhubarb (Rheum rhabarbarum) is an herbaceous edible perennial and a member of the buckwheat family which forms large fleshy rhizomes and large leaves with long, thick (and tasty) petioles (stalks). The leaf petioles (leaf stalks), can reach 30 to 45 cmlong and two to 5cm thick with a crispy texture similar to large celery stalk. The leaves are toxic and because of the oxalic acid content which can cause human and animal poisoning and must be trimmed from the petiole prior use.
Variety Selection
Variety selection
Growers select varieties based on stalk colour (which can range between red and green), plant size, stalk thickness and length, flavour and tartness, yield, depth of dormancy (chill units required), and the tendency to form seed stalks. There is also resistance to pest and disease criteria especially in heavy soils. Finding a particular variety of rhubarb to meet all this demand it is often a challenge.
Soil
Soil
Rhubarb has reputation for growing on a different range of soil textures and conditions. This includes sands to heavy clays and sands plus organic or peaty soil. A well drained retentive soil is ideal. Cold, poorly drained fields must be avoided as this will delay maturity, reduce yields and reduce the length of the life of the plantation. The modern market requires consistent supply of good quality crop. This has to be produced from land that will provide the crop with its needs over a long season. Rhubarb does not like acidity and as with any perennial crop it is difficult to correct low pH later on in the plantation life. A soil test should be done prior to planting to determine pH level. Soil pH should be maintained at 6.5-7 on mineral soils.
Planting
Planting
Planting can be carried out from October until March providing that plants are dormant and soil is free draining. Soil cultivations must be carefully timed to avoid soil compaction which could affect crop establishment and reduce the cropping potential of the plantation. The ‘sets’ are ideally large chunks of the original plant or ‘crown’ and should have at least one good bud showing. The base of this bud should be under the soil with the top just showing.
Nutrition
Nutrition
Rhubarb is a nutritionally hungry crop and is very responsive to fertiliser. The quality of the crop harvested depends to a large extent on the care and fertilization received. Soil sampling should be undertaken before planting to determine nutrients concentration. Phosphate and potash are applied as base fertilisers before planting with nitrogen applied in spring after planting.

Fertiliser(kg/ha)

N

P

K

Mg

Establishment year

125

150

225

60

Production years

250

100

250

60
Planting density
Planting density
The traditional density of 76 cm x 92 cm gives 14,346 stations per hectare and this has been demonstrated as being optimal for a range of varieties.
Irrigation
Irrigation
Irrigation is needed to help on establishing newly planted plantations. Irrigation should be applied in accordance to soil moisture levels and not exceeding.
Pests and diseases
Pests and diseases
The outdoor crop is relatively free from disease although the crowns can rot from within with a bacterial condition called Crown rot. This is the most widespread and important disease of Rhubarb. The main problems lie in propagation and newly planted crops.
Downy Mildew can cause serious leaf damage and can affect petiole quality. This has been observed in Norfolk in the last years. Slugs and leather jackets are a potential problem in the establishment year, otherwise no routine pesticides required. Sometimes the leaves and not so much the sticks could be damaged by caterpillars. This need treatment if will develop to an epidemic proportion.
Perennial Weeds
Perennial weeds
Perennial weeds are a problem in rhubarb and every effort has to be made to clear up the weed before planting. The worst weeds are creeping thistle, couch, perennial nettle and willow herb and bramble and It is advised to follow an arable rotation. Division of weed infested crowns will result in re-infestation of the perennial weed.
Forcing
Forcing
The forcing of rhubarb has been practised on a commercial scale for over a century in this country. It is traditionally grown in and around the Wakefield area of Yorkshire .The crop is brought from the fields when dormant and is packed into sheds in which it is grown in complete darkness. Forced yields will be reduced if the crowns have not broken dormancy by exposure to low temperature in the field before transfer to the forcing shed. This requirement for a period of low temperatures can be measured by a system of “units of cold”. The cold unit requirement for forcing has been determined experimentally for the main varieties.

Cold units

Cold units

The system of calculating cold units is used on taking daily soil temperatures at 10cm below level. Starting with a base line from 10 degrees Celsius, the figures below this temperature are recorded as cold units and are added together from day to day. Temperatures over 10degrees Celsius are ignored in daily accumulations.

For instance - soil temperature is 10 degrees = 0 cold units

Soil temperature is 5 degrees = 5 cold units
Soil temperature is 3 degrees = 7 cold units
Soil temperature is -3 degrees = 10 cold units

Date	10 cm soil temp	Degrees C below
	8 am GMT (°C)	base of 10° C

1 Oct	8	2
2 Oct	7	3
3 Oct	6	4
4 Oct	11	-
5 Oct	10	0
6 Oct	8	2

	Total cold units Accumulated	11

Plant varieties and selections trials including day neutral
Plant varieties and selections trials including day neutral
On this section of the project we are carrying out a report with scoring criteria where ten known varieties are analysed and measured for plant health, plant vigour, yield potential stalk size and colour against a controlled variety.
We have also produced clonal selection for six out of these ten varieties where clones are compared and analysed for differences in yield, stalk size and colour against the mother plant.
The clones selected are commercial varieties for the market.

The controlled variety chosen to be measured against is Timperley Early.
On a scale from 1 to 5 will measure Plant health, Potential Yield, stalk size, stalk colour.
CLICK ON CHART IMAGE FOR INFORMATION
Stalk size

Length (1 – very short stalk; 5 – very long stalk)
Thickness (1 – very thin stalk; 5 – very thick stalk)
Comparing and analysing rhubarb varieties on stalk size we can observe that Goliath has shorter stalks than Timperley Early and excepting Holsteiner Blut and Victoria the other varieties have longer stems.

We have scored stalk colour comparing the other varieties to Timperley Early.
We measured stalk colour starting from 1 – green to 5 - dark red.
Timperley Early stalks are red at the base rising to green to the tip and we have scored with 3. Compare to Timperley Early, Holsteiner Blut, Sutton Seedless, Victoria and Fenton’s Special has similar colour characteristics.
Champagne, Stockbridge Arrow, and Livingstone have red stalks which hold colour better than Timperley Early. Raspberry Red is the variety with highest quality of deep red stalks.

In order to analyse the potential Yield, we have compared rhubarb varieties with the information gathered from the past years. These figures could vary from season to season and in different areas. The average rhubarb yield is 50 tonnes per hectare.
Considering that we have scored potential yield from 1 to 5, where 1 is less than 40t/ha and 5 is 60 t/ha over.
Timperley Early produces an average yield, just over 50t/ha, being scored with 3.
Compared with Timperley Early, Raspberry Red, Victoria, and Stockbridge Arrow produce less and Goliath, Fenton with Livingstone produce higher yields.
Variety overview
As a result of scoring criteria we have identified that Sutton Seedless, Stockbridge Arrow, and Livingstone are the varieties that get very close to the maximum of marked quality criteria in terms of size, colour and yield.