Schriften zu Genetischen Ressourcen - Genres

Sugar beets and related wild species – from collecting to utilisation
China, India as well as Central and West Asian countries interesting distinct landraces
may still exist but these countries are difficult to access either because of their
sheer size (China - leaf beet landraces) and/or political reasons (India, Pakistan, Afghanistan).
The main promoters of Beta collecting missions (IPGRI, USDA/ARS, German-Dutch
cooperation, Turkish genebank) began to change the objectives of collecting trips
from capturing useful genetic variations to monitoring and in situ management of
Beta genetic resources. There are indications that species like B. macrocarpa (Portugal
and Spain), B. macrorhiza (East Caucasus), B. lomatogona and B. vulgaris
subsp. (Azerbaijan, inland wild type) are threatened by genetic erosion. To prevent
discontinuation of the evolutionary processes in these species, the WBN recommended
assessing the threat of genetic erosion case wise and to promote and establish
in situ management programmes for the extant populations in the relevant
areas. In particular, wild species of the sections Nanae and Corollinae are not
adapted to the climatic conditions of Northwest German lowland. They are subjected
to a very strong selection pressure towards adaptation to “genebank seed production
procedures”. Loss of genetic variation in ex situ collections as well as a lack of precise
information on the magnitude of genetic erosion within natural growing sites underlines
the urgent need for in situ monitoring projects.
Maintenance
Beta germplasm collections consist of species and populations with a remarkable
diversity of breeding systems and survival strategies (annuality, seed dormancy,
seed hardiness, frost resistance, variation for day length reaction and cold requirement).
Parts of the section Beta germplasm does not at all require vernalisation and
starts bolting only 40 days after sowing like B. vulgaris subsp. adanensis while accessions
from Ireland bolt incompletely even after a prolonged vernalisation period.
The timely induction of bolting and flowering is only one of the technical management
aspects ex situ managers of Beta collections have to consider. The WBN recommended
compiling a seed production manual that is available at the BAZ Gene Bank
since 1996. The manual describes experiences made at the location of the BAZ
Gene Bank and is valid for this location, only. Some of the experiences are summarised
in Table 2. At the BAZ Gene Bank young plants are produced routinely during
autumn, winter and early spring depending on the type of germplasm and vernalised
artificially if required. The information given below refers to that cultivation method.
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