Prima gland clover

Origin

Prima was developed from an ecotype (ref. NYT2447) collected by J. S. Katznelson in 1976 in the Yehudiyya Forest, Golan, Israel. It was donated to the Australian Trifolium Genetic Resource Centre (ATGRC) and grown for characterisation and seed multiplication in 1993 under the Commonwealth Plant Introduction Code. It was selected for further evaluation in a Grains Research and Development Corporation funded project and it has been under national field evaluation by NAPLIP (National Annual Pasture Legume Improvement Program) since 1997.

Prima gland clover flowers

Description and area of use

Prima gland clover is an aerial seeding, self-regenerating annual pasture legume. It has hairless, waxy leaflets that are rounded in the rosette stage and become elongated as stems develop. The stems are slender and can reach 30-40cm in height when ungrazed. Flowering generally begins in mid September or between 100 and 110 days after sowing in Perth. The flowers are a distinctive light to dark pink colour and form into a globular head. Each floret will contain 2-3 small, yellow, oval shaped seeds of around 0.7mg. The hardseed level is high at senescence and will drop rapidly over late autumn to around 40-50% in mid winter. Prima has a high level of tolerance to redlegged earthmite (Halotydeus destructor), moderate tolerance to aphids and is susceptible to lucerne flea. Prima is not susceptible to clover scorch.

The maturity and hardseed dynamics of Prima are ideally suited to mediteranean climates with above 350mm of annual rainfall. It will grow on a range of soil pH (4.5- 8.0 in CaCl₂) and textures except poor infertile sands and can tolerate mild waterlogging. Seed crops however should target fertile sandy loams to clay loams with mildly acid to neutral pH. The hardseed level and breakdown will suit either crop:pasture rotations or longer term ‘phase’ type pastures between continuous cropping sequences. Prima is ideal for including in pasture mixtures to provide a backup pasture legume in situations of false break and heavy redlegged earthmite populations. The ease of seed production will allow on farm bulkup and therefore a more affordable large scale adoption.

Studies into the biochemical nature of the insect tolerance in Prima gland clover suggest it is based on a moderate level of the chemical coumarin. The presence of coumarin-containing species in fodder is of concern to animal health when spoilage occurs during haymaking. Fungal activity during spoilage can convert coumarin to dicoumarol, a vitamin K analogue, and in sufficient dosage and exposure can result in haemorrhage. The risk of this occurring with Prima gland clover is considered low due to:

• The relatively low coumarin level compared to the Melilotus spp. that are associated with the problem in north America.
• Artificial spoilage of pure Prima gland clover resulted in nil or low levels of measured dicoumarol.
• Sheep grazing dry Prima residue did not show any difference in blood clotting compared to a control group. During this grazing period the stubble was moist for several days after a significant summer rainfall event.

To further minimise this risk it is recommended that hay should not be cut from pastures containing a high level of gland clover. If hay does contain gland clover and spoilage occurs this should not be feed to any type or class of stock.

Field performance

The novel nature of Prima and the high level of insect tolerance required a check against adverse reaction in grazing stock. This involved a comparison of growth and meat quality between 14 month old Merino ewes which had been grazed on either Prima or Dalkeith pasture for up to nine weeks. The plots were sown on the 3 July 2000, at 30kg/ha after weed control with a knockdown herbicide. The plots were stocked initially at six sheep/ha on the 7 September and this was increased every three weeks to a maximum of 12 sheep/ha.

On 9 November, all sheep were removed from the plots and transported to Linley Valley abattoir in Wooroloo where they were slaughtered according to normal protocols at a commercial abattoir on 10 November. The carcasses were hung for three days in the chiller prior to measurement of cold carcass weight, carcass yield, fatness, eye muscle area and colour. The backstrap was then removed and delivered to Curtin University of Technology for evaluation of flavour, tenderness, juiciness and taste by a trained taste panel. Further determination of off-flavours and taints was evaluated using a triangle test to differentiate the test samples from commercially available lamb (obtained through WAMMCO). The major findings were:

Gland clover seed crop

Establishment

As with all pasture legumes, successful establishment relies on good weed control. Establish Prima after one or more non-legume crops and use a knockdown herbicide prior to sowing. Seed should be inoculated and lime pelleted using group C inoculant. Sowing rate for seed production should be between 5-7kg/ha. The small seed size requires a shallow sowing depth (maximum 1cm) and establishment will benefit from rolling after sowing. Prima can be sown at 1-2kg/ha in mixtures with other pasture legumes such as subterranean clover, annual medics, biserrula and serradella. Seed crops should not be grazed inorder to maximise seed yield. In pasture settings, grazing pressure should be reduced from the onset of flowering. Seed production crops should be fertilised adequately with phosphate and potassium. Recommendations based on soils tests for a pulse crop could be used as a guide. Prima seed crops should be monitored for lucerne flea and pasture loopers and treated with an appropriate insecticide if present.

Herbicides

There are no currently registered herbicides for gland clover. The following observations are based on experimental situations and hopefully registration of the more useful herbicides will occur as Prima gland clover is commercially adopted. Off-label use of herbicides is not recommended.

• No adverse reaction to any of the common selective grass herbicides has been observed.
• Pre-emergent applications of trifluralin, metachlor and diuron can mildly reduce density at establishment.
• Post emergent applications of Broadstrike appear safe while mild damage has been observed with Spinnaker.
• Prima does not tolerate bromoxinyl and can be badly damaged by winter and spring applications of paraquat,diquat and glyphosate.

Harvesting

Prima seed can be harvested with a conventional, open front cereal harvester, provided the stand reaches an adequate height. A finger tine reel is preferred, particularily if lodging has occurred, however crops can be successfully harvested with either a bat or air reel. Prima seed heads thresh readily and therefore the settings of concave clearance and drum speed are not critical. However the fine seed will require a much lower fan speed (50-60% of that used for wheat). Sample purity can be assisted with the use of a canola screenas soon as all the heads are dry, although the base of stems may be slightly green. There does not appear to be any advantage in swathing. Dessicant herbicides (for example, diquat) may be required in some situations if plants or weeds are still green. It is unlikely that large quantities of seed can be harvested with a clover harvester because of difficulties in separating the seed from sand. Prima seed requires scarification before sowing to increase its germination percentage. The use of unscarified seed will result in poor establishment.

Harvesting Prima seed

Production and marketing

Prima is a public variety and can be freely bought and sold.

Production guidelines for Prima gland clover seed include:

• Target a fertile sandy loam to clay loam soil.
• Sow after one or more non-legume crops.
• Avoid paddocks with a background population of small seeded legumes such as balansa, cluster, woolly burr or haresfoot clover.
• Avoid paddocks where prohibited weeds are present.
• Inocululate and lime pellet seed using group C inoculant.
• Fertilise well with both phophate and potassium.
• Sow at 5-7kg/ha.
• Sow shallow, ideally at 0.5-1cm. Rolling after sowing is an advantage.
• Monitor for lucerne flea and pasture loopers. Control with an appropriate insecticide if present.
• Apply a suitable grass selective herbicide in mid winter.
• Harvest with an open front header using concave and drum setting similar to wheat but a reduced fan speed.
• Harvested seed purity benefits from the use of canola and/or Hannaford screens.
• Harvest as soon as the seed heads and base of the stem are completely dry.