Serradella - Part E Seed production
Seed production
Reliable seed production requires irrigation or favourable rainfall. Opportunity seed production is possible in most districts in good seasons. A well managed irrigation crop of Avila at Cowra yielded 2.5 t of hulled seed/ha. Dryland yields are highly variable and depend on good rainfall, variety, and management. A typical yield from a well managed dryland serradella pasture is 300 kg hulled seed/ha.
Seed certification is available for some varieties; for further information contact NSW Agriculture.
Paddocks selected must be free of many broadleaf weeds, as the choice of herbicides for weed control is limited. A paddock that has a history of cropping with effective weed control is ideal.
To prevent damage to harvesting machinery, select relatively level paddocks that are free of sticks, stones and stumps.
While serradella grows on a wide range of soil types, the best seed yields are obtained on well drained deep sandy loam soils that are neutral to moderately acid. Varieties differ in their tolerance to soil acidity, and their seed yields vary accordingly.
A high density of plants is desirable from the first year, so seeding rates should be heavier than for normal pasture sowing. A sowing rate of about 2 kg/ha of dehulled seed or 6 to 10 kg/ha of `enhanced´ seed is recommended. Good preparation of seedbeds and timely sowing are important prerequisites for success.
Pre-emergent registered herbicides, applied according to directions, control several major grass weeds and some broadleaf weeds. All weeds, including grasses such as barley grass and ryegrass, should be controlled early. A range of registered products is available (see the NSW Agriculture booklet Weed control in lucerne and pastures). Serradella is sensitive to many herbicides. High application rates of some registered products can damage serradella.
Seed production needs high soil fertility. In many situations fertiliser rates such as 250 kg/ha of single superphosphate (or equivalent products), possibly with the addition of molybdenum, should be applied at sowing.
Heliothis caterpillars can be particularly damaging to seed crops. Control of other pests, such as blue oat mites during establishment, is important for high seed yielding crops.
To allow ease of harvest by conventional harvesters it is important to minimise grazing so that plants grow to their maximum height. Careful grazing with sheep may be preferable to grazing with cattle to ensure less disturbance of the soil surface and more even grazing. Remove animals from seed production areas when the first flowers appear.
If moisture is adequate, serradella sets pods until development is restricted by high temperatures in late spring or summer.
Irrigation timing and management are critical for success. If autumn rains are likely to be erratic, water in early autumn to allow timely sowing. Irrigate to avoid stress during the growing, flowering, and early pod filling stages. Irrigate up to the end of November (mid-December in milder climates) and allow the stand to dry down for harvest as seeding is completed.
As the plants dry down the leaflets drop, followed by the pods. The leaves form a dense mat on the ground. The mat helps to prevent many pods falling on to the soil.
Harvest starts when most of the pods are dry. The vegetative material in most instances will also be dry. If spring is late and wet for harvest, a desiccant may be needed to rapidly dry the green plant material.
The pods of several varieties begin falling as they mature. However new varieties, such as Cadiz, Santorini, Charano, and to a degree King, retain their seed pods much better than older varieties. Flowering extends over a considerable period of time and pods mature over an extended period. It has been difficult to time harvest before a significant percentage of ripe pods have fallen, however, this is less of a problem with some of the newer varieties.
If the pods are very dry and weathered, segmentation and germination are improved. But again, the more mature the crop the more the seed falls to the ground, and for many operators proves difficult to retrieve.
Consult the header manufacturer’s manual for optimum performance. The front of the conventional header needs to operate very close to the ground to pick up the crop. The drum should be closed with a speed of 1100 to 1600 r.p.m. The tailboard should be set so that unthreshed pods are returned to the drum. Threshing efficiency varies with the humidity and regular adjustments may be required through the day.
The speed of travel should be very slow to ensure maximum threshing to break up plant material. The cutter bar should be close enough to the ground to allow pods to be combed into the open front by the pickup reel. It may be necessary to remove the skid plates on the front to allow lower harvesting. Paddocks need to be absolutely free of sticks and stones.
Some pods pass through the harvester in balls of threshed material. These can be retrieved in following operations.
Pods are difficult to segment for some varieties and require thorough threshing. They may also accumulate in the header bins with sand, soil, serradella stalk and other plant material. The header bin must be unloaded frequently to prevent harvest material packing in the auger. In some seasons green material (weeds or serradella) with a high moisture content may make the seed mass difficult to move through the auger.
Follow the harvest by raking the header trails into windrows. Set the rake to tickle the soil surface and pick up any loose pods into the windrow. The windrow is threshed through the header again.
About 60 per cent of the pod is picked up in the first harvest operation and 20 per cent with the second pass of the header. Vacuum harvest the residue.
Vacuum harvesting
Use a threshing drum with a wire mesh concave and four bars (two clover, two medic), with a clearance of 4 to 5 mm at the entry duct, closing to 1 to 2 mm at the exit. The drum shaft should run at a minimum speed of 500 r.p.m.
The varieties that tend not to segment can be pre-cleaned to remove small weed seeds, soil and inert matter. When the pods fail to segment, process them through a purpose-built serradella dehuller or alternatively a hammermill, or peg drum. The hammermill should have knives. Drive at 400 to 600 r.p.m., or as slowly as possible to allow good cutting without breaking the seed.
Aspirate to remove soil and dehulled seed after hammermilling.
The cleaning of serradella is very slow and for many cleaners is only 200 kg/hour. The dehulled seed is separated from the hulled fraction by a screen of about 1.6 mm. Dehulled seed is cleaned through a conventional air screen cleaner and indents, and passed over a gravity table to be bagged.
Hulled seed can be dehulled using a modified seed scarifier or dehuller.
Purchasing seed
The buyer of seed needs to know the purity, freedom from weeds, germination percentage, soft seed content, hard seed content and the number of seeds per kilogram.
Check if Plant Breeders Rights (PBR) covers the variety or varieties that you wish to purchase. The NSW Agriculture agnote PBR - What it means to you (ISSN-6848) details obligations and restrictions to buyers and sellers of seeds covered by this legislation.
Purchase of a PBR protected variety means that for individual farmers there are restrictions. The major restriction to those that purchase seed of a PBR protected variety is that the current seed or the seed of subsequent harvests cannot be sold for sowing without the permission from the breeder or his agent.
This restriction includes seed sale and trading between farmers. There are, however, exemptions to these restrictions. Firstly seed may be held over on farm for own use. PBR protected lines may also be used on farm by either or both partners in a bona fide share cropping situation.
Further information
Further information and advice is available from the district agronomist at your local office of NSW Agriculture, from the seed production officer at your local regional headquarters of NSW Agriculture, or seed company representative.
Acknowledgements
Financial support was provided by the Grains Research and Development Corporation for evaluation of serradella varieties in NSW.
Financial support was provided by the Australian Meat and Livestock Research and Development Corporation for evaluation of serradella in NSW.
Agriculture Western Australia, and CLIMA, in particular Dr Brad Nutt, who provided considerable information, assistance with research programs, and seed of many varieties.
NSW Agriculture officers, especially Col Mullen and Dr Alison Bowman (who conducted much of the research relevant to this publication), Warren McDonald (advice and editing), Ken Archer (negotiation and organisation for registration and release of new varieties), Bryan Mathews (supervision of several of the trial research programs), and Margaret Jones (typing).
Notes on pasture improvement
Pasture improvement may be associated with an increase in the incidence of certain livestock health disorders. Livestock and production losses from some disorders are possible. Management may need to be modified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement.
The Native Vegetation Conservation Act (1997) restricts some pasture improvement practices where existing pasture contains native species. Inquire through your office of the Department of Land and Water Conservation for further details.
Always read the label
Users of agricultural (or veterinary) chemical products must always read the label and any Permit, before using the product, and strictly comply with the directions on the label and the conditions of any Permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or omitted to be made in this publication.
