High levels of bruchid damage and very dry weather at harvest in 2018 have led to variable bean seed quality.
Field bean samples tested at PGRO from August to October 2018 had an overall average germination capacity of 79.5%, with winter beans having an average of 79% and spring beans 83%. Germination can be affected by physical damage to the seed caused when harvesting over-dry crops, chemical contamination by glyphosate, or insect damage such as bruchid damage, and if saving seed on-farm, it is important to test seed for germination capacity.
At low levels of bruchid infestation, germination losses may not be significant in larger seeded varieties, although damaged beans can be more susceptible to moulds. It’s likely that lightly infested seeds have a greater chance of survival, with the size of seed and portion remaining following larval feeding being important determinants of germination capacity.
At high levels of seed damage by bruchid, germination is affected, and losses between 10 and 15% germination have been recorded in laboratory tests when bruchid damage is between 40% and 80%. There is potential in the field for the damage to cause seeds to decay before germination occurs, and damage close to the point of attachment with the hypocotyl can cause establishment failure.
This occurs more frequently when bruchid damage levels are high. Crops that are harvested at low moisture content, particularly when less than 12%, may incur mechanical damage during harvesting or cleaning.
Mechanical damage to seed causes seedling abnormalities and increased infection by soil-borne pathogens such as damping off (Pythium spp.), lowering the germination capacity.
If glyphosate has been used as a desiccant, seedling abnormalities are likely to arise if the seed from the treated crop is used.
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