Factors affecting grain crop seed germination

Page last updated: Tuesday, 28 November 2023 - 2:20pm

Please note: This content may be out of date and is currently under review.

Other factors (contamination with weeds, crop-topping, frost and green grain)

Green wild radish contamination

Wild radish with green pods

Contamination is quite common in wheat and lupins, especially in years with late rains when wild radish continues to grow and remains green after crop maturity. This contamination is especially damaging to crop seeds in grain silos because the green wild radish pod gives off substances that actually kill the stored seeds.

The brassica family (to which wild radish belongs) is notorious for the number of volatile toxic substances it produces. The toxins inhibit germination and metabolism, since the affected seeds generally die. Those that emerge result in seedlings with abnormal roots and shoots.

Research into the sensitivity of lupins, field peas, wheat and barley to radish toxins found all four crops to be sensitive. Lupins seem to be the most sensitive and in one experiment, the viability of lupin seed dropped by 20% after just 5 days with 5% contamination with green radish pods (weight by weight).

The higher the contamination level and the longer the storage period, the greater is the damage to the crop seed.

If wild radish is found growing in crops at or near harvest time, avoid harvesting areas of green wild radish if the seed is to be saved for the next year's crop.

In years with late rains, when wild radish continues to grow and remains green after crop maturity, the moisture squeezed from the wild radish stems during harvest often raises the grain moisture content above acceptable storage levels.

Crop-topping and dessication

When the crop is sprayed prior to physiological maturity, grain viability is likely to be reduced. For this reason, glyphosate is not registered for use on seed crops. For more information refer to Crop-topping pulse crops.

Frost-affected grain

Frost affected grains should be graded out prior to seeding. Generally the grains are easily cleaned out when grading as they are lighter in weight.

Green grain – harvested too early

Harvest can theoretically start as soon as the grain moisture falls below about 20% moisture content. Late tillers in cereal crops, can proivide a a source of green sappy grains in early harvested grain samples. There is a lack of information about what happens to green grains during storage or drying and how viable they may be.

Contact information

Helen Spafford
+61 (0)8 9166 4074