Onobrychis viciifolia Scop.

COMMON NAMES

Sainfoin, St Foin, holy grass

 

DESCRIPTION

Pubescent perennial with many erect or sub-erect, hollow stems , 60–80 cm or more, arising from basal buds on a branched root stock. After defoliation , branches develop from axillary buds on the stem nodes of the remaining stubble.  Leaves pinnate with 5–14 pairs of obovate leaflets and a terminal leaflet. Stipules broad and finely pointed. Numerous pinkish red melliferous flowers, borne in erect, conical racemes on long axillary stalks. Root system consists of a deep tap root with a few main branches and numerous fine lateral roots  bearing most of the rhizobial nodules. Common or single-cut sainfoin  flowers mainly in the year after establishment  and thereafter for many years, as this type is very persistent. Giant or double-cut sainfoin lacks persistence  and flowers in the establishment year and thereafter for only 2–3 years; it has longer erect but less dense stems than common sainfoin. Flowers cross-pollinated, mainly by honey bees; the flattened, indehiscent seed pods  contain a single kidney shaped seed, 4–6 mm, dark olive to brown or black in colour. The proportion of hard seeds  in harvested seed crops can be 15–20 percent. Number of seeds kg-1: 50 000 (hulled or podded) and 67 000 (dehulled). Average 1000-seed weight: 20.0 g (hulled) and 14.9 g (dehulled).

DISTRIBUTION

Distributed in parts of warm-temperate Europe and Asia, and on dryland, calcareous soils in western North America. Cultivated in some Mediterranean environments, e.g. southern Italy.

CHARACTERISTICS 

Growth  Performs best on deep, well-drained calcareous soils at pH levels of 6.0 and above. It has vigorous seedling growth. Thin dry soils require irrigation  to improve forage yield. Adapted to warm temperate climes (Frame, Charlton and Laidlaw, 1998). Erect growth habit, suited to infrequent cutting for conservation  (hay or silage ) rather than grazing . Longevity varies with ecotype or cultivar.

It has a spring to autumn growth period, and seasonality of growth varies from the single flush of growth of the common type to the double flushes of the giant type. A rest period is required in late autumn to allow plants to build up the organic reserves in the roots  needed for winter survival and initiation of spring growth. It has excellent drought resistance because of its deep-rooting characteristic, and is intolerant of prolonged flooding.

Compatibility in mixture  Non-aggressive grasses such as timothy  (Phleum pratense ) or meadow fescue  (Festuca pratensis ) are compatible. The addition of white clover  or birdsfoot trefoil  can be advantageous in stands cut for hay and aftermath grazing . Wheatgrasses (Agropyron spp. ) are suitable as companion grass es for dryland conditions (McGinnies and Townsend, 1983; Griggs and Matches, 1991).

Temperature  Sainfoin has a wider optimum temperature range for germination and early seedling growth than most other forage legumes (Smoliak, Johnston and Hanna, 1972). Periods of high temperature adversely affect subsequent yields , especially following defoliation , since the plant’s ability to support high metabolic rates is reduced (Kallenbach, Matches and Mehan, 1996).

Winter cold can reduce plant persistence  (Jefferson et al., 1994). High reserves of N in legume roots  during winter are believed to aid cold hardiness (Volonec and Nelson, 1995).

Light  The sainfoin  canopy utilizes incident radiation less effectively than alfalfa  because of a lower leaf area index (LAI) and less erect growth habit. Flowering is favoured by long daylengths.

Water supply  In the absence of irrigation , annual  rainfall of at least 330 mm required (Miller and Hoveland, 1995). Water use efficiency, at 15–18 kg DM mm-1 evapotranspiration, is high in spring, equalling that of alfalfa  (Bolger and Matches, 1990), but is lower than that of alfalfa later in the season. Irrigation in dry periods aids yield and plant persistence .

Nitrogen fixation  Colonization of sainfoin  roots  is by rhizobial strains common to other legumes from the same (Hedysarae) and related (Galegae) tribes. Rhizobial inoculation of sainfoin seeds  is needed when sown onto land that has been free of legumes for several years. A suspension of crushed nodules from another crop has sometimes been used for inoculation.

Nitrogen fixing efficiency is less than that of alfalfa or red or white clovers, since sainfoin requires about 20 mol CO2 to fix l mol of N2 compared with about 10 mol CO2 for the other legumes (Witty, Minchin and Sheehy, 1983). Energy availability may be the limiting factor since sainfoin allocates less assimilate for leaf production and LAI than does alfalfa.

BREEDING

It is cross-pollinated, mainly by honey bees (Apis mellifera), with chromosome numbers of 2n=2x=14 for diploids and 2n=4x=28 for tetraploids. Breeding objectives include improved forage yield, persistence  and tolerance of grazing .

Cultivars  Modern bred cultivars do not rigidly align with one or other of the two main original types, common or giant, but are more flexible in their characteristics. Named cultivars include Melrose and Nova (Canada); Remont and Renumex (United States of America); Othello (Australia); Incoronata, Vala and Zeus (Italy); and Fakir (France).

A seed crop can be taken in place of a main hay crop of common sainfoin , or following a hay cut in giant sainfoin, which flowers and seeds  twice in a season. Seed yields  can reach  1450 kg ha-1 (Hoveland and Townsend, 1985).

Using the Fodder Plant Seeds Regulations for the United Kingdom as an example, certified and commercial seed require a minimum germination of 75 percent and a maximum hard seed content of 20 percent by number of pure seeds . The required analytical purity is 95 percent by weight for certified and commercial seed. The maximum permissible  content of seeds of other species is 2.5 percent by weight for certified and commercial seed, and l.5 percent for the higher voluntary standard of certified seed.

AGRONOMY

Establishment  A well-cultivated, uniform and firm seed bed  is required for good results. It is best sown direct for successful establishment , but can be undersown in a cereal crop. On dryland in western Canada, seeding sainfoin  in alternate rows with Russian wild rye  (Psathyrostachys juncea ) rather than sowing the components in the same rows enhanced persistence  because of reduced inter-species competition (Kilcher, 1982). Drilling at 20–30 cm depth is advisable, i.e. about twice as deep as red clover , and covering well with soil. On irrigated land, monocultures are usually sown in spring at 40–60 kg ha-1 for dehulled seed and 80–120 kg ha-1 for hulled. Slower-germinating, hulled seeds  are sometimes chosen for situations where germination is only wanted after there has been sufficient rainfall to ensure sufficient seedling development. Much lower seed rates are used in dryland conditions. Seed can be protected from fungal attack by dressing with thiophanate methyl (Nan, 1995).

The addition of a non-aggressive companion grass , e.g. meadow fescue  (6 kg ha-1) or timothy  (2 kg ha-1) increases stand density and reduces weed invasion.

Nutrient requirements  An adequate status of available soil P is necessary for successful establishment . After removal of hay crops, soil P and K replenishment is required to maintain plant persistence  and yield, though sainfoin  is tolerant of soils with a low P status (Miller and Hoveland, 1995). Liming may be necessary to sustain soil pH  at 6.0 and above.

Weeds  Sainfoin monocultures lack competitiveness against weed invasion compared with sainfoin +grass stands. Serious infestations of perennial weeds  should be controlled by  herbicides before soil cultivations.

It is tolerant of ‘sainfoin -safe’ herbicides, e.g. MCPB, 2,4–D or bentazone types, applied at an adequate stage of growth. Winter-applied carbetamide is an option for weed grass control in monocultures.

Pests  Sainfoin is resistant to many of the pests  that attack other forage legumes. Significant pests noted in the United States of America are: Rhizobium-nodule-eating weevil (Sitona scissifons); Lygus bugs (Lygus spp.); and the sainfoin  bruchid (Bruchudius unicolor) (Gaudet et al., 1980).

Diseases  Compared with many other legumes, sainfoin  is relatively disease resistant. It can be adversely affected by clover rot (Sclerotinia trifoliorum) and sometimes powdery mildew (Erysiphe trifolii) or verticillium wilt (Verticillium albo-atrum).

Forage production  Variable, as DM yields  may range between 7 and 15 t DM ha-1 depending upon growing conditions. Yields are about 20 percent lower than those from alfalfa , contributory factors including a lower LAI, a less erect canopy structure and less efficient N2 fixation.

NUTRITIVE VALUE

This is largely determined by stage of growth at time of utilization since nutritive value falls with increasing plant maturity and associated stemminess; data from Quebec, Canada, are shown in Table 1.

Sainfoin is protein and mineral rich in comparison with grasses, but its Ca and Na concentrations are lower than in other major legumes. Its mineral composition is shown in Tables 2 and 3. A notable feature of sainfoin is the concentration of condensed tannins in the leaves . Hence its forage does not cause bloat in animals, and the tannins also protect protein in the rumen, thus enhancing the supply of amino acids for absorption in the small intestine of ruminants (Waghorn et al., 1990).

Table 1.  Nutritive value of sainfoin (g kg-1 DM) at three stages of primary growth (Means of 3 cultivars over 3 years).

Stage of growth

Crude protein

Cell contents

Neutral detergent fibre

Acid detergent fibre

Digestibility

Flower bud

146.1

582.4

417.6

296.0

636

10 percent flowering

114.4

524.7

475.3

344.7

591

Full flowering

102.0

491.9

508.1

369.6

557

Source: After Gervais, 2000.

Table 2.  Mineral composition of sainfoin at three stages of primary growth (Means of 3 cultivars over 3 years).

Constituent

Stage of growth

Flower bud

10 percent flowering

Full flower

 

–––––––––––  g kg-1 DM  –––––––––––

Ca

13.8

15.3

15.7

P               

2.5

2.8

2.8

K               

21.2

19.5

19.7

Mg

1.8

2.0

2.0

Na             

0.18

0.19

0.18

S               

2.4

2.5

2.4

 

–––––––––––  mg kg-1 DM  –––––––––––

Mn

53

58

56

Zn             

38

42

38

Cu             

11.9

12.6

11.6

Fe             

189

222

174

Source: After Gervais, 2000.

Table 3.  Nitrogen and mineral composition of sainfoin.

Constituent

Content range

 

g kg-1 DM

N

20.0–45.6

P                      

2.0– 5.5

K                      

11.8–36.9

Ca                    

8.4–13.1

Mg                    

1.4–11.6

S                      

2.0–3.4

Na                    

0.1–0.5

Cl                     

3.2–4.6

 

mg kg-1 DM

Fe                    

73–360

Mn                    

44–62

Zn                    

20–41

Cu                    

5.0–10.4

Co                    

0.10–0.24

Mo                    

0.18

Source:  After Spedding and Diekmahns, 1972.

Both grazed and conserved sainfoin or sainfoin-rich forages are highly acceptable, leading to high animal intake s of forage (e.g. Griggs and Matches, 1991).

UTILIZATION

Grazing management  Rotational rather than continuous  stocking  is best for stand persistence  and production. Sainfoin cannot tolerate overgrazing during the growing season and plant persistence benefits from a 6-week rest period from grazing  before winter. The accumulated forage can then be grazed after the plants have become dormant. Common sainfoin  is more tolerant of grazing than giant sainfoin. Modern cultivars have been bred for better persistence and regrowth after defoliation .

Conservation management  Sainfoin is highly suitable because of its upright growth habit and its pattern of regrowth from axillary buds after defoliation . Shattering and loss of nutritious leaf is a hazard if haymaking  is prolonged. Because of a lower buffering capacity i.e. resistance against pH reduction during the ensilage process, sainfoin  herbage has a better ensilability than alfalfa .

ANIMAL PERFORMANCE

Sainfoin gives highly satisfactory individual animal performance . Among other legumes, only white clover  was superior to sainfoin  as judged by lamb growth (Ulyatt, 1981b).

MAIN ATTRIBUTES

It is a productive protein- and mineral-rich legume suited to calcareous dryland soils, and responds to irrigation  on shallow soils. Condensed tannins in the leaves  prevent bloating in ruminants and also improve the efficiency of protein metabolism.  It has high intake characteristics.

MAIN SHORTCOMINGS

It is slow to establish, and not adapted to a wide range of soil and environment conditions. It is unsuited to intensive grazing .

MAIN REFERENCES  

Gervais (2000); Frame, Charlton and Laidlaw (1998); Miller and Hoveland (1995).

LINKS

  • Sainfoin: description
  • Montguide
  • Montana Interagency Plant Materials Handbook
  • BioImages: The Virtual Field-Guide
  • The potential of sainfoin as a forage crop: article
  • Trial of Sainfoin Cultivars
  • Sainfoin.com
  • Additional Information by Jason Koivisto and Gerry P.F. Lane, Royal Agricultural College, Cirencester UK. [Pdf-file]