Timely management decisions leading into harvest will ensure grain growers capture the best quality seed to maximise yield and reduce the collection of defective seeds and foreign matter.
NSW DPI Senior Research Scientist researching seed defects of chickpeas, Dr Jenny Wood, said as harvest approached late rain events and late frosts increased the risk of defective grain in desi chickpeas
“A survey conducted by NSW DPI found that some growers lost considerable amounts of profit due to grain defects on delivery of chickpeas in 2017,” Dr Wood said.
“Late in the season when chickpeas have podded and seeds are filling, frosts can result in shrivelled grain which is small, dark and wrinkled. These grains are classified as defective under the Australian Pulse Standards, which can be found via the Pulse Australia website.”
In some areas in 2007, significant rain fell when chickpea plants were at physiological maturity. This caused the plants to re-initiate growth and set new pods at the tops of the plants. In these cases, careful consideration should be given to the timing of desiccation.
Desiccation of green seed containing pods will result in the death of these seeds. These seeds could be classified as either immature or green seeds at receival. Green seeds will have green seed coat or cotyledons while immature seeds will also be small. Both are classified as defective.
The maximum allowable defective seed in desi chickpea at receival (Farmer Dressed Minimum Receival Standard) is 6% (by weight) and includes frosted, immature and green seeds amongst others. However, there is also a poor colour classification that captures green cotyledons, with a maximum tolerance of 2% (by weight) and is included within the 6% defective class.
The other issue with green and immature seeds is that they can have a higher moisture content, so are more likely to be affected by mould growth in storage. The maximum allowable tolerance for mould is only one affected seed in a 200g sample.
To optimise desi chickpea yield and minimise the chances of seed defects in the harvested sample, growers are advised to:
- Take care in deciding exactly when to desiccate
- Harvest on-time
- Check and adjust your combine settings in every crop to capture the best quality grain
Dr Wood said growers will need to make decisions for each paddock and variety according to the forecast weather, aiming to time desiccation to maximise yield and quality by minimising the chances of dry seeds becoming weather damaged and minimising green, immature seeds from the top of the plant.
“Don’t harvest too early, as the maximum moisture content is 14%, Dr Wood said.
“But don’t harvest too late as delayed harvests will reduce your yields through pod loss, shattering, moisture loss (= lost tonnage) and will increase chances of weather damage, another defect.
“It is also important for growers and contractors to test and fine-tune the set-up of headers in each paddock of chickpeas. Optimised settings can improve yield and reduce defective material from making it into the bin.
“Growers are reminded to regularly stop and blow clean combines to reduce the risk of fire from build-up of debris and dust.”