Improving the identification, handling and storage of “difficult” seeds ...

Legume
forages
Grass
forages
back, can be regarded as normal if the first leaf is intact or only slightly damaged.
Hard seed, i.e. seed which remain hard at the end of the test period because they
have not absorbed water, may occur in the legumes. Report the % of hard seed
found and a method to remove hardseededness may be applied to these seeds. This
can be achieved by mechanical scarification such as careful piercing, chipping,
filing or sand papering. However, be careful to apply this to the small to medium
seeds where the scarification may damage the embryo and the seed may then be
rendered dead or the emerging seedling damaged and show abnormalities.
Often grass seed can be dormant, especially in freshly harvested seed. Unfortunately
experience has proven that a specific dormant grass seed does not always react to a
specific pre-treatment and no specific treatment can be applied to all grass seed. This
has most probably to do with the state of dormancy of the particular seed. As the
analyst is usually unaware of the state of dormancy, more than one method, including
interactions of methods can be tried out e.g. the basic method involves a "top of
paper" substratum incubation at 20/30°C (16h/8h) in the presence of dark/light cycles
(16h/8h). Treatments can involve pre-chilling for 5 days at 5°C; a 0,2% KNO 3
treatment; a combination of the latter two treatments in interaction; dry storage;
preheating for 7 days at 30–35°C; application of Gibberellic acid (GA 3 ) are just a few
that can be tried to break dormancy.
Constraints (question 5.10)
▪ Accurate seed storage behaviour information
▪ Germination protocols
▪ Regeneration of cross-pollinated species
▪ Capacity and training in the sciences of tissue culture and cryo-storage
▪ Maintenance of field gene banks
Possible solutions to the constraints
▪ Increased research in the field of PGR conservation, i.e. seed storage behaviour and germination
protocols
▪ Increased opportunities for training as well as improved knowledge of available training
possibilities
▪ Improved infrastructure for the regeneration of cross-pollinated varieties, i.e. isolation cages.
▪ Capacity building in alternative ex-situ storage methods of recalcitrant species other than field
gene banks in order to reduce the risks and costs of maintaining accessions in field gene banks.
▪ Faster, easier and non-destructive moisture testing