Leguminosae

Common names

Gland clover

Description

Gland clover is a semi erect annual legume with glabrous leaves and stems. Leaflets are smooth, trifoliate, round in shape when young, becoming elongated in mature plants. Stipules are green, semi-ovate and sharply toothed with the tip often ending in a gland. Leaflets are 1 to 2 cm long, oblong and sharply toothed with or without glands between the teeth. Stems are green and smooth but can display some reddening on the upper surface. It grows to a height of 40 –50 cm in spring. Flower heads are ovate to round, born on stalks. The calyx tube is white, the corolla is pink to mauve in colour, deepening in colour with age. Pods have 2-3 seeds. Seeds are ovoid and yellow in colour (Zohary and Heller 1984).

Distribution

Native to the Mediterranean region of Eurasia; Albania, Greece, Turkey, Syria, Lebanon, Israel (Gillet et al. 2001). Sown in pastures in southern Australia in areas with Mediterranean rainfall distribution pattern receiving 350 to 600 mm annual rainfall.

Characteristics

Suited to a range of soil types ranging from neutral to mildly acid and from well drained to mildly waterlogged. Not suited to deep acid sands.

Season of growth

Autumn to Spring. The cultivar Prima is early maturing, flowering about 100-115 days after sowing with a maturity similar to Dalkeith subterranean clover.

Frost tolerance

Has tolerated light frosts to –5⁰C.

Drought tolerance

Moderately drought tolerant, similar to balansa clover

Tolerance of flooding

Has been grown successfully on heavy clay soils subject to periodic temporary waterlogging over winter. Showed good growth in waterlogged soils (Gibberd et al. 2001).

N Fixation

Rhizobial relationships

Nodulates very effectively with Rhizobium trifolii strain WSM 409 (Group C in Australia), but has nodulated less effectively on naturally occurring rhizobia in old subterranean clover pastures.

Nitrogen fixing ability

Plant tissue typically has a nitrogen content of 2.5-2.8%N with up to 75% of its N being derived from biological fixation.

Ability to spread naturally and regenerate

It has a high proportion of hard seed and slow rate of hard seed breakdown which allows it to withstand summer drought and regenerate the following spring. Its small seed size allows a large proportion of the seed to pass through the rumen of animals undigested and spread in the dung. It will spread widely from where it is sown where there is no competition from other species.

Sowing requirements

Land preparation for establishment

Being small seeded it requires a well-prepared fine uniform seed bed for sowing.

Sowing methods

Can be drilled or broadcast into a conventionally-prepared seed bed.

Sowing time, depth and rate

It is drilled at 1-3 kg/ha in autumn at a depth of no more than 1 cm. Lower sowing rates can be used when sown as part of a mixture. Seed crops should be sown at 5-7 kg/ha.

Seed characteristics

Seed size

Seeds are approximately 0.7-1.0 mg or 1 to 1.2 mm.

Percentage hard-seeds

Gland clover is very hard-seeded with greater than 90% hard at maturity. Approximately 40-50% of seed of the cultivar Prima is hard at the beginning of the following growing season. Gland clover has a delayed hard-seed breakdown pattern with most seed remaining hard until late autumn (Norman et al. 1998). Experimental results indicate as much as 20% of the original seed can be expected to be present as a seed reserve 3 years after production.

Nutrient requirements

Gland clover has similar nutrient requirements to other annual legumes and requires adequate levels of phosphorus, sulphur, potassium and molybdenum.

Compatibility with other legumes and grasses

It can be grown in mixes with subterranean clover, yellow serradella, annual medics, biserrula and lucerne, but due to its small seed size, may be susceptible to competition during seedling establishment.

Breeding system

Chomosome number 2n=16

Breeding objectives

The Australian Trifolium Genetic Resource Centre holds 26 accessions which vary in leaf shape, maturity, flower colour and insect resistance. Prima was selected for good insect resistance, low coumarin levels and the absence of types with a laciniate leaf.

Insect and disease tolerance

Gland clover has proven to be very resistant to insect pests having a high level of tolerance to red-legged earth mites (Halotydeus destructor), blue-green aphids (Acyrthosiphon kondoi), and cow pea aphids (Aphis craccivora). However, it is moderately susceptible to spotted alfalfa aphids (Therioaphis trifolii), and susceptible to lucerne flea (Sminthurus viridis). The insect tolerance is considered to be associated with the coumarins contained in the leaves (Wang et al. 1999). Prima is not susceptible to clover scorch disease (Kabatiella caulivora).

Nutritional quality, animal production and uses

Dry matter yields

Studies in Australia found T. glanduliferum averaged 97% of the dry matter production of Dalkeith subterranean clover in ungrazed swards over a number of sites and seasons. Herbage yields at the end of spring of up to 5.0 t dm/ha have been recorded in Western Australia and 5.7 t dm/ha in New South Wales.

Palatability

Gland clover has similar palatability to subterranean clover.

Response to defoliation

Gland clover tolerates similar grazing to other annual legumes except it is more sensitive to heavy grazing during flowering than legumes such as subterranean clover. It should only be grazed lightly once flowering has commenced. It develops a more prostrate growth habit when grazed. Seed crops should not be grazed in order to maximise seed yields.

Feeding value

Young sheep (wethers) have showed similar liveweight changes grazing T. glanduliferum to a control group grazing a mixed serradella/subterranean clover pasture. During summer, sheep grazing dry pastures also maintained a comparable liveweight to the control group. Taste tests of meat from sheep fed on gland clover could not detect any abnormal flavours.

Anti-quality factors

Analysis of extracts from gland clover indicate that it contains coumarins which are thought to convey the high level of insect tolerance. The levels of coumarin found in green Prima gland clover ranged from15 to 40 ppm (15-40 ug/g). These values are low compared with those found in Melilotus species. The levels of coumarin and dicoumarol are substantially lower than those found in sweet clover and below what are considered critical levels to cause animal health problems.

Fodder conservation

Gland clover, and pastures containing this legume, can be conserved. As with all conserved fodders, mouldy hay should not be fed to livestock and additional care should be taken given the presence of coumarin in gland clover, even though the level in the cultivar Prima is low.

Main attributes

The main advantages of Prima as a pasture legume, relative to early maturing subterranean clover cultivars, are related to the combination of broad soil type adaptation, ease of seed production, high levels of hard-seed for protection against false breaks (premature germination) and good resistance to red-legged earth mites and blue-green aphids.

Main short comings

Susceptibility to competition during establishment and need to restrict grazing during flowering.

Seed production and cultivars

Seed yields

Seed yields up to 1000 kg/ha have been achieved in well managed seed crops but yields of 300-700 kg/ha are more typical.

Seed harvesting methods

Seed is readily harvested with conventional open fronted cereal harvesting machinery due to its upright growth habit and flowers held at the top of the stems (Nutt et al. 1999). Seeds can shatter readily with disturbance and are too small to be suction harvested. Seeds should be harvested when heads are dry and 75% of the stem dry. Concave settings must be reduced to 50-60% of that used for wheat due to the small seed size. Seed must be scarified prior to sowing to increase the germination percentage.

Cultivars

One cultivar, Prima, has been developed by Brad Nutt and the Centre for Legumes in Mediterranean Agriculture (CLIMA) in Australia from an ecotype collected by J. S. Katznelson in 1976 in the Yehudiyya Forest, Golan, Israel. Seed of Prima was released commercially in 2002 (Dear et al. 2001).

Links

Agnote DPI-397: Gland clover

Agfact P2.5.42: Gland clover

Main references

Dear, B,S, Sandral, G.A., Nutt, B., Wilson, B., Rodham, C., and Taylor, J. (2001) Gland clover- a new insect resistant legume. p 63-64. (ed. K. Kondon), In Proceedings 16^thAnnual Conference of NSW Grasslands Society Conference. Gundagai, New South Wales.

Gibberd, M.R., Gray, J.D., Cocks, P.S., Colmer,T.D. (2001) Waterlogging tolerance among a diverse range of Trifolium accessions is related to root porosity, lateral root formation and 'aerotropic rooting'. Annals of Botany 88: 4, 579- 589.

Gillet, J.M., Taylor, N.L. and Collins, M. (ed.) (2001) The world of clovers, Iowa State University Press, Ames.

Norman, H.C., Cocks, P.S., Smith, F.P., Nutt, B.J. (1998) Reproductive strategies in Mediterranean annual clovers: germination and hardseededness. Australian Journal of Agricultural Research 49, 973-982.

Nutt, B.J., Loi, A., Falcinelli, M. (ed.) Rosellini, D. (1999) Harvestability of annual Mediterranean pasture legumes using conventional crop machinery. Herbage seed as a key factor in improving production of and environmental quality. Proceedings Fourth International Herbage Seed Conference, Perugia, Italy p78-82.

Wang, S.F., Ghisalberti, E.L., Ridsdill-Smith, J. (1999) Volatile components from Trifolium species plants. Phytochemistry 52, 601-605.

Zohary, M. and Heller, D. (1984) The Genus Trifolium, The Israel Academy of Sciences and Humanities, Jerusalem, Israel.