Push for pulse quality
From the February 2009 edition of Agriculture Today.
Seed quality at sowing can have a major impact on crop performance and resulting yield at the end of the season - particularly in pulse crops.
A number of factors in producing lupin seed can greatly affect germination and establishment.
Harvest timing and header set up can have a big impact on seed quality.
Pulses need to be harvested at the correct time.
The problem is that pulses are often not high priority, so harvest is delayed in preference of harvesting cereals first.
Research shows that seed quality is optimum when lupins are harvested with seed moisture at 15 per cent.
Harvesting at or below 12pc moisture can greatly reduce quality, lower germination and increase shattering.
While it is too late to do anything about quality at harvest now, there is plenty to consider in making sure the seed you next sow has the best chance to establish.
Firstly, how you store your seed now is important.
Seed stored with high moisture content can deteriorate, particularly if stored at high temperatures.
Research shows seed stored at 13-14pc moisture at 20 degrees loses little quality, however, above 30C quality loss is considerable.
Avoid excessive handling, as seed is easily damaged by the header and handling during harvest, grading and sowing.
A most important factor for achieving good establishment is to do a germination test before sowing, either in a laboratory or at home, making sure you only count the healthy seedlings.
Grading seed is important for good establishment because seed size affects time to emergence.
This is particularly important when sowing on marginal moisture or when sowing depth is uneven.
Larger seeds germinate faster and emerge earlier and faster than medium and small seeds, leading to an increase in root length, relative to smaller seeds.
Seed size and vigour was particularly important last year with a lot of drought affected small lupin seed.
Not only does size affect seedling vigour, it can have an impact on sowing rates.
It is important to do a 100 seed weight before calculating your sowing rate.
Last season a number of lupin crops had very high plant populations because small seed at sowing resulted in a much larger number of established plants per square metre.
This high plant population in turn led to further problems at the end of the season, with increased moisture stress in the dry conditions again resulting in small seed and low yields at harvest.
Seed quality is also important for quality grain production.
Wild lupin seeds contain quinolozidine alkaloids which defend the plants against pathogenic organisms and herbivores.
The presence of alkaloids limits lupin consumption as they produce a bitter taste.
These alkaloids have been bred out of most commercial varieties.
The narrow leaf lupin is free of high alkaloid or bitter seed.
There has been an effort to remove the bitter seed contamination which was frequent in albus lupin.
So remember that if you are sowing Albus lupins to have seed tested for bitterness contamination.
The industry limit for contamination has set a zero bitter contamination level for seed used at sowing.
Testing can be done free of charge at NSW DPI’s Wagga Wagga laboratories.
Contact your local district agronomist for further information.
