Hedysarum coronarium L.
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Hedysarum coronarium L.
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Leguminosae
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Author:
Dr. John Frame
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Common names Sulla, Italian sainfoin, French honeysuckle. Description Biennial or short-lived perennial, semi-erect to erect growing, 0.3 to 1.5 m, with succulent, pinnate leaves which have oval to round leaflets arranged in pairs, 7-15 pairs per leaf, and a terminal leaflet. Leaves glabrous above and hairy below. Stems thick and succulent becoming woody after full flowering. Strongly tap-rooted, over 2m, with numerous secondary roots. Flowering begins in early summer, mellifluous inflorescences being racemes with up to 35 florets, ranging from pink to violet, but commonly crimson, and cross-pollinated mainly by bees. Seed pods have three to eight ovoidal segments per pod which split into unhulled seeds with a rough, thorny surface ; hulled seeds are creamy white to light brown and flattened with an almost circular profile. Distribution Originated in western Mediterranean and North Africa where it occurs from sea level to the frost line in the uplands. Used for forage in semi-arid and arid regions (Kernick, l978). Important for grazing, silage, hay or green feed in southern Italy where circa 250 000 ha grown (Martiniello and Ciola, l994). Also being grown for evaluation in Iberian peninsula, New Zealand and USA. Characteristics In the wild sulla is present in natural pastures and fallows, often in association with Phalaris, Dactylis or Festuca spp. Adapted to deep calcareous clays in winter-mild areas with a range of winter rainfall from 400 to 1000 m. Persistence in sown pure stands drastically reduced in the third harvest year. Season of growth Autumn to spring, drying off with summer heat. Sowing date and autumn rainfall influence growth throughout the year. Vigorous autumn growth occurs in the second harvest year. Frost tolerance Cannot tolerate temperatures much below freezing point. Wild plants in North Africa more cold tolerant than Italian cultivars. Drought tolerance Medium tolerance. Tolerance of flooding Not tolerant. Soil requirements Thrives on soils with pH greater than 6.0-6.5 with free forms of Ca (Gutiérrez Más, l986) but likely to fail on acid or waterlogged soils. Adequate available P is necessary when seeding. Rhizobial relationships Rhizobial inoculation of seed required when sown in soils without a previous history of growing sulla. Requires a specific strain of Rhizobium hedisari for effective nodulation (Krishna, l993). Ability to seed naturally Inconsistent. Land preparation for establishment Well-cultivated, uniform, weed-free and firm seed bed required for good establishment. Sowing methods Hulled seed can be broadcast or drilled but unhulled seed can only be broadcast. Can be undersown in a cereal crop. Sowing depth and soil cover Shallow sowing, 10-20 mm, is essential, particularly for unhulled seed. Sowing time and seed rate Usually sown in autumn through into early winter if hulled seed used. Unhulled seed germinate unevenly in comparison with hulled. Seed rates are 20-25 kg/ha (hulled seed) and 40-60 kg/ha (unhulled seed), though half these seed rates are recommended in New Zealand (Foote, l988). Number of seeds per kg 215 000 to 230 000 for hulled seed reported from southern Italy. Circa 90 000 (unhulled) and 190 000 (hulled) reported from New Zealand by Charlton (l992). Circa 230 000 for hulled Italian commercial seed. Percentage hard seed Can be high if seed ripened during hot, dry period. Seed treatment before sowing The hulling process indirectly aids scarification of the seed coat of harvested seed. Nutrient requirements Liming is necessary on acid soils. Responds well to P and K application. Compatibility with grasses and other legumes Sulla is sown pure when hay is the objective since grasses are at a competitive disadvantage. In New Zealand, for grazing, can be sown with grasses such as phalaris (Phalaris aquatica) or prairie grass (Bromus willdenowi) which have open growth habits though grass/sulla swards are not common in Italy. Ability to compete with weeds Weed invasion, especially of perennial grasses or broad-leaved weeds, can adversely affect sulla at establishment but can be controlled by a pre-emergence herbicide such as trifluralin. Weeds can also be a problem after cutting for conservation. Seedling vigour Moderate. After germination remains at rosette stage for 10-12 weeks and can be grazed at this stage. Later, vigorous growth comes from the crown. Vigour of growth and growth rhythm Growth in spring is more vigorous than in the autumn-winter period ; dormant in hot, dry summers but commencing again with autumn rainfall. Growth after grazing is initially slow. Response to defoliation After defoliation, regrowth comes mainly from leaf axils or scars located on the plant crown (Krishna and Kemp, l993). Does not persist under frequent, severe defoliation. Grazing management A New Zealand recommendation for established swards is to graze at 30-50 cm foliage height (circa 3-5 t DM/ha), a sward state achieved in 6-8 weeks in spring there and every 8-10 weeks during summer and autumn. Plant crowns from which new growth emerges after defoliation are less likely to be damaged than with continuous stocking. Breeding system Cross-pollinated mainly by honey bees. Chromosome number 2n = 4x = 16. Breeding objectives Greater plant longevity. Better forage quality by selecting for plants with numerous thin stems. Improved persistence under grazing. Dry matter yields Under semi-arid conditions in southern Italy and Sardinia, 6-7 t/ha achieved from sulla pastures grazed by dairy sheep (Martiniello and Ciola, 1994 ; Sulas et al., l995). In other Italian trials, 6.6 and 9.6 t/ha for non-irrigated and irrigated stands, respectively, were reported (Martiniello et al., 2000) ; these yields were superior to those of sainfoin (5.2 and 5.8 t/ha) for the respective treatments, while the nutritive value of sulla was also superior. In New Zealand trials, yields up to 18 t/ha have been recorded under both sheep grazing (Krishna et al., l990), cattle grazing (Foote, l988) and cutting (Rys et al., l988). Suitability for hay and silage Growth characteristics, especially of erect, thin-stemmed types, make sulla suitable for preservation. Good-quality hay can be made if cut at the flowering rather than the traditional seed pod stage while good-quality wilted silage can be made because of sulla’s high water-soluble carbohydrate content (Stringi et al., 1997). Feeding value High value, especially leafy forage in winter/early spring before increased stemminess (Pinto et al., l993). Retains protein-rich leaves better than lucerne when dried. Contains condensed tannins which prevent bloat in livestock and which improve protein utilization (Niezen et al., l995 ; Waghorn et al., l999) however, some adverse effects of condensed tannins on performance have been noted when fed as a sole feed, an effect which could be diluted by growing sulla with species e.g. grass species, which do not contain tannins (Douglas et al., l999). Acceptability Highly acceptable forage (leaves, stems and flowers) for cattle and sheep whether grazed, cut for green fodder or preserved as hay or silage. Seed harvesting methods Grazing should cease before the start of spring and the crop harvested when 50% of the seeds are brown and the other half purplish-red. Usually mown and then windrowed for a few days before threshing. Seed yields 200-500 kg/ha in New Zealand (Foote, l988) but under irrigation in Italy, over 1500 kg/ha achieved in trials (Martiniello and Ciola, l994). Cultivars Several local selections in Mediterranean region are, e.g. Grimaldi, Sant Omera and Sparacia (Italy) and Aigaion (Greece). In New Zealand, Grasslands Aokau and Necton have been released. Diseases Powdery mildew (Erysiphe trifolii) can have adverse effects on stand performance. Seed pods may be attacked by the weevil, Bruchophagus gibbus. Main attributes Good yields of forage of high feeding value and highly acceptable to livestock. Suitable species for grazing, silage, hay or green fodder. No risk of bloat. Main shortcomings Relatively short-lived. Unsuitable for intensive grazing. Performance In grazing trials, better lamb performance was achieved from sulla than from grass/white clover, a result attributed to a very high readily fermentable to structural carbohydrate ratio (Terrill et al., l992). Better performance of lambs grazing sulla compared with lucerne was attributed to the protective effects of condensed tannins on nematode infection and protein protection in the rumen (Niezen et al., l995). Links
Main reference Frame et al. (l998): Kernick (l978); Martiniello and Ciola (l994); Waghorn et al. (l999) Other references Charlton (l992); Douglas et al.(l999); Foote A.S. (l988); Gutiérrez Más J.C. (l986); Krishna (l993); Krishna and Kemp (l993); Krishna et al. (l990); Martiniello et al.(2000); Niezen et al.(l995); Pinto et al.(l993); Rys et al.(l988); Stringi et al.(1997); Sulas et al.(l995) |