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From the field to the lab – low temperature studies of blackcurrant plants

This study explores the concept of plant hardiness, specifically the ability of blackcurrant plants to withstand environmental stress such as cold temperatures. It examines different cultivars and their cold hardiness, as well as the effect of rootstock on hardening ability. The study also explores the cryosurvival of the cultivars and the potential impact of geographical origin.

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From the field to the lab – low temperature studies of blackcurrant plants

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  1. From the field to the lab – low temperature studies of blackcurrant plants J.E.Green, B.W.W.Grout, E.E.Benson Writtle College, University of Essex

  2. Concept of Plant Hardiness • Ability of a plant to withstand environmental stress. e.g. high concentrations of salt, drought, cold. • 2 factors to consider when discussing hardiness: • Plants ability to withstand environmental stress during period of active growth. • Ability of the plant to adapt to the stress factor, known as hardening or acclimation.

  3. Definitions of Cold Hardiness • Winter hardiness – ability of buds to survive freezing events. • Spring frost hardiness – ability of growing buds to withstand/re-acclimate to low temperature, and avoid or minimise damage. • Foliage hardiness – level of damage to membranes caused by freezing.

  4. It has been observed that different cultivars have different cryo-survival rates. Do these differences also occur in the field? 3 groups of cultivars Cold hardy Intermediate hardiness Soft Geographical Origin and Cold Hardiness

  5. Cold Hardiness of Cultivars

  6. Origin of ‘Hardy’ Cultivars • Brodtorp is a selection of R.nigrum from Finland • growth habit is hardy and compact, highly self-fertile, and early flowering. • Ojebyn is a seedling selection of R.nigrum from North Sweden • growth is of dwarf habit, and is very cold hardy. • Svyriai is a derivative of R.dikuscha and R.nigrum var. sibiricum from Russia. • has been identified as being winter hardy.

  7. Origin of the Ben Series • The Ben series were bred at the Scottish Crop Research Institute (SCRI) to produce varieties/cultivars with • increased pest and disease resistance, • more tolerance to adverse weather conditions at flowering time, • consistently heavier crops • growth habits more suited to machine harvesting. • All the Ben series are considered to be of intermediate hardiness to cold.

  8. Origin of English Cultivars • Baldwin is an old variety of unknown origin. • of pure R.nigrum descent as are the other ‘soft’ cultivars. • Green’s Black, is probably Boskoop Giant crossed with Carter’s Champion • flowers in the early midseason, reaching full flower a day earlier than Baldwin. • Westwick Choice, is a Baldwin seedling. • growth and flowering occur in the early midseason

  9. What is an Exotherm? • Exotherms are an increase in temperature caused by ice formation. • What are the significance of exothermic events?

  10. Is the Primary Exotherm a Lethal Event? • Excised buds frozen at 0.1 ºC min-1 until they had a freezing event. (-15 ºC). • Buds surface sterilized and placed on cotton plugs in half strength liquid ribes media. • After 1 week, buds dissected and • meristems moved to fresh media. • All cultivars had 100% survival rates. • Primary exotherm not lethal.

  11. What is the Effect of Prolonged Freezing Temperatures? • Cuttings frozen at 0.1 ºC min-1 to -20 ºC. • Cuttings then removed at 0, 3, 6, 9 days at -20 ºC. • Placed in water and left at 20 ºC. • Bud break occurred in all cultivars at all temperature treatments. • Growth was slower in cuttings frozen for longer, but cuttings were still viable.

  12. Cryo-Survival of Field Plants • Slow freezing of cuttings to -38 ºC. • Transferred to LN. • Regrowth? • Cultivar differences have been oberserved in mulberry (Sakai).

  13. Foliage Cold Hardiness • Cold temperatures reduce enzymatic activity, alter metabolism, and decrease the photosynthetic capacity of plant tissues (Dubey 1997). • In unstressed, healthy plants, electrolytes are maintained within the membranes. • In cell membranes these changes associated with loss of integrity. • REL = conductivity after 1 hour –5 °C (µS/cm) conductivity after LN(µS/cm)

  14. Changes in REL in 3 cultivars of differing geographical origin

  15. What Effect Can Rootstock Have on Hardening Ability? • Can a ‘cold hardy’ rootstock increase the ‘cold hardiness’ of a cold sensitive cultivar? • Grafts were made of

  16. Effect of rootstock on REL of the scion

  17. Cryopreserve the cultivars and compile a ranking of survival rates. Does the geographical origin have an effect on the cryosurvival of the cultivars? What comes next?

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