The quality of the crop seed used at sowing can greatly influence the productivity and profitability of the crop. If a grower is using retained seed, it must be tested prior to sowing to ensure only high-quality seed is selected for processing and sowing.
Many farmers retain harvested seed for the following season, which can greatly reduce input costs. However, seed quality is variable between varieties and even between batches of the same variety, creating the risk of sowing low vigour seed.
Low quality delays germination and inhibits early vigour, sometimes costing more in lost production than the money saved by retaining seed. But it is possible to make an informed decision about retaining seed or purchasing better quality commercial seed if the seed is tested.
Germination tests involve germinating seeds under laboratory conditions, and recording the amount of viable seedlings during a seven day germination period.
Ideally a germination of at least 90 per cent is expected, with the rate of germination then used to calculate seeding rates, and describe the vigour of the seed lot. If the seed lot is determined to be of low vigour, increasing the seeding rate to compensate won’t improve plant vigour, and may be difficult to sow.
Testing for thousand seed weight allows the determination of seed size. The thousand seed weight can be strongly affected by the grain fill achieved by the preceding crop, with large variations possible.
These weights should be recorded for each batch of retained seed, as seed weight, and size can influence sowing rate and plant population. If the seed size is determined to be large, this will require a higher sowing rate to achieve appropriate plant density when compared to a smaller seed size.
Testing for vigour in the form of germination and emergence tests, and determining sowing rate by using the thousand seed weight test, are essential strategies when retained seed is utilised. These tests will enable a grower to make informed decisions regarding seed retention and purchase.
