Wet harvest could impact seed viability

December 29, 2017

GRDC Southern Panel member Kate Wilson

Recent heavy rainfall through parts of the southern cropping region could impact on the viability of grain that growers are planning to retain for sowing in 2018.

Any grain subjected to wetting at harvest is more susceptible to poor germination, low vigour and degradation during storage and handling.

Grains Research and Development Corporation (GRDC) Southern Regional Panel member Kate Wilson encourages growers to closely scrutinise seed being set aside for planting.

Mrs Wilson, a grain grower and agronomic consultant, says it is essential that growers determine whether damage to grain caused by rain at harvest is purely cosmetic or the symptom of a seed-borne disease which will impact on germination.

‘‘To ensure establishment of a healthy crop next season, it is important to pay particular attention to the seed that is being saved for sowing,’’ she said.

‘‘Proper management of the seed starts at harvest and should continue right through to storage, handling and seeding next year.’’

Mrs Wilson said growers should also be aware that some cereal varieties are more susceptible to the effects of late season weather damage.

To assist growers in determining whether grain is viable for sowing and what is an appropriate and effective seed management program, the GRDC offers a detailed ‘Retaining Seed Fact Sheet’.

It states that the symptoms of seed quality deterioration can range from mild, such as a loose and wrinkled seed coat in some pulses, to more advanced, such as seed staining, fungal mould and visible signs of germination.

Unless canola seed was harvested before any weather damage it should not be retained for sowing due to the vulnerability of canola’s small seed.

Any retained seed should be graded and tested for germination and vigour. Testing for seed-borne disease is also recommended, especially with saved pulse seed.

Other key points growers should consider when retaining grain for seed include:

●While a laboratory seed test should be used to establish the germination percentage of on-farm retained seed before sowing, especially if it has been weather damaged, a simple on-farm germination test can be done in soil. This will give a good indication of emergence and seedling vigour as at germination.

●Seed-borne disease generally cannot be identified from visual inspection so requires laboratory testing.

●Achieving and maintaining low temperature, humidity and grain moisture content for stored grain is even more critical if grain has been weather damaged. As weather-damaged seed deteriorates faster than sound seed it should not be stored for more than 12 months.

●With many weedy pulse and cereal crops in a wet season, desiccation or crop topping often becomes necessary. Depending on timing and chemicals used, this could affect seed quality for sowing.

●Grain must not be retained for seed when glyphosate has been used in pre-harvest applications.

●Seedling emergence can be affected by sowing too deeply, cold or wet soil, some seed dressings and herbicides, and hard-setting soil.

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