Flax Seeding

Seeding

Flax usually does well on types of land suitable for wheat. It grows best on soils with high water-holding capacity and good inherent fertility. However, one disadvantage of heavy soils is their tendency to crust after heavy rains and interfere with the emergence of the seedlings. The use of zero tillage can greatly alleviate this problem. Flax does not thrive on sandy soils unless a large supply of moisture is available. Imperfectly drained soils may result in yellowing and stunting of flax. However, flax will usually outgrow this yellowing. 

Poorly drained land, or land subject to excessive drought or erosion should not be sown to flax. Flax is moderately tolerant to salinity, provided that fertility levels are suitable and adequate moisture is available during germination.

Choice of Seed

Use good, preferably certified, seed of a recommended variety. Certified seed is tested to ensure minimal weed content, genetic purity and good germination. Certified seed consistently yields better than cleaned seed and produces a higher net return from the crop. If farm-produced seed is used, it should be thoroughly cleaned to remove weed seeds and only sound kernels retained.

Seed Quality and Effect on Plant Stands

Reductions in stand must be expected when using untreated, damaged seed. Damaged seed is prone to decay by soil micro-organisms, and the seedlings that do emerge are weak and prone to develop seedling blight. Resulting stands will be poor, uneven, low yielding and lacking in vigour. 

Seedlings produced from damaged seed may germinate very slowly and may be weak, or show a variety of abnormalities. Common abnormalities include injured root tips, broken or cracked cotyledons, split hypocotyls, twin radicles, radicles trapped inside the seedcoat, and roots that are blunt, broken, long and spindly, or gnarled and distorted.

Seedbed Preparation

Method of Seeding

Flax should be sown shallow, 2.5 to 4.0 cm (1 to 1.5 in.) deep, with a drill that places the seed at a uniform depth in rows 15 to 20 cm (6 to 8 in.) apart. Recent research has shown that up to 30 cm (12 in.) row spacing in zero tillage is acceptable. Depth of seeding trials at the University of Alberta have shown that seeding depths greater than 3 cm (1.2 in.) result in significant reductions to emergence and yield.

The most satisfactory results are achieved by using a drill equipped with press wheels which firm the soil around the seed. If a drill does not have press wheels, a soil packer may be drawn behind the drill, or the field may be packed in a separate operation.

The effect of pre-seeding tillage in terms of the type of implement, the depth of tillage and the effect of packing, either before or after seeding, has not been clearly defined. Studies at the University of Alberta have shown that deeper tillage results in poorer stand development but because this practice often leads to extensive tillering, there are not necessarily yield losses. The same effect was noticed with both pre-seeding packing and post-seeding packing. As a general rule, pre-seeding packing was beneficial even to land that also had post-seeding packing.

Rate of Seeding

In general, the seeding rate should be adjusted according to size of seed, germination percentage, soil fertility, or weediness. In tests conducted in Saskatchewan and Manitoba, flax showed little yield response to changes in seeding rate from 25 to 55 kg/ha (22 to 49 lb./ac.). A seeding rate of 30 to 45 kg/ha (27 to 40 lb./ac.) is recommended.

Higher seeding rates may be required for varieties with a yellow seedcoat (e.g. solin varieties), particularly if seed treatment is not applied. Excessively high seeding rates should be avoided where lodging may be a problem.

On land under irrigation, seeding rates as high as 50 kg/ha (45 lb./ac.) can be used. However, if conditions for establishment are good, 33.6 to 39.2 kg/ha (30 to 35 lb./ac.) is adequate if weeds are controlled.

With irrigation, plant populations of 300 seedlings/m2 (30/ft.2) are adequate for optimum yield. It is extremely important to choose a variety that has a high level of resistance to lodging, since high soil moisture and fertility generally increase the potential for lodging.

Plant Stand

A seeding rate of 30 to 45 kg/ha (27 to 40 lb./ac.) results in approximately 500 to 800 seeds/m2 (50 to 80 seeds/ft.2). A seedling emergence rate of 50 to 60% is usually attained under farm conditions.

According to Manitoba Crop Insurance, yields are not significantly affected by reduction in plant stands from 400 to 300 plants/m2 (40 to 30/ft.2), but yields generally tend to drop off as stands drop below 300 plants/m2 (30/ft.2). However, even at plant stands as low as 100 plants/m2 (10/ft.2), yields were reduced only about 20%, as extensive tillering compensated for the lower stands.

Reseeding

If seedling stands are thin, a decision must be made whether to reseed or not. Flax seedling emergence is sometimes poor due to damaged seed, soil crusting, seedling diseases, adverse weather conditions, deep seeding, herbicide injury, or other reasons. Generally, yields are lower the later the seeding date, and lower because of loss of soil moisture from additional tillage. The added costs of reseeding must also be taken into account.

Seeding Date

Early Seeding

Early seeding of flax generally produces the best results, for flax is seldom damaged by light spring frosts. Plants just emerging are the most tender, but can withstand temperatures down to approximately -3°C (27°F). After the seedlings have passed the two-leaf stage and are hardened by exposure, they can withstand temperatures as low as -8°C (18°F) for a short time without damage. Unlike cereals, where the growing point of the seedling is protected under the soil surface, the growing point of the flax seedling is fully exposed above the ground and is more vulnerable to frost.

Moderate temperatures and ample soil moisture during flowering and seed development favour high yield, high oil content and high oil quality. Such conditions are more likely to occur with early seeding. As well, seeding in mid-May generally results in somewhat less lodging. High quality straw for fibre is also more likely to be obtained when flax is seeded early.

Late Seeding

Late seeding of flax often results in much lower yields. Tests in Manitoba showed that compared to early seeding in May, a delay of seeding to June 1, June 10 and June 20 resulted in respective yield reductions of 7%, 29% and 52%. Late seeding also reduces oil content and seed size. Because green stems and second growth are more prevalent in a late-seeded crop, harvesting is more difficult.

However, a delay in seeding of flax may be necessary if herbicides are not used to control early starting weeds such as wild oats, or when drought or excessive moisture have delayed field work. When seeding is delayed until after June 1, only early maturing varieties are recommended because of the risk of fall frosts. Flax varieties differ in their performance under conditions of late seeding.

Water Use and Irrigation

Flax and Irrigation Suitability

Flax is an excellent crop for irrigated crop rotation since it is not prone to Sclerotinia stem rot which affects canola, sunflower, peas, and beans. The major effect of irrigation on flax is to promote a second or third flush of flowers and to maintain adequate moisture for plant growth until all flowers have developed seeds.

Root Development and Water Uptake

In non-restricting soils (medium-textured soils that are amenable to lots of moisture), flax develops a short, branched taproot, encompassing a rooting zone of 1 m (39 in.). Root development is nearly completed by the flowering stage. On irrigated land, flax takes approximately 70% of its water requirement from the top half of the root zone.

Water Requirements Throughout the Season

Over the growing season, crop water use may be as high as 41 cm (16 in.).

  • Seedling Stage: 1 to 3 mm/day (0.04 to 0.12 in./day)
  • Flowering Stage Peak: Up to 7 mm/day (0.28 in./day)

The critical water requirement period for flax is from flowering to just prior to seed ripening. Therefore, to maximize yield and oil content, adequate soil moisture must be maintained during that period.

Irrigation Management Best Practices

Monitoring moisture use by soil moisture sensors, crop water use models, or direct measurement of crop use, is important if adequate soil moisture is to be maintained. However, the last irrigation of flax should be completed by the second week in August to ensure that the seeds ripen. Extending the last irrigation past this time will encourage continued growth in the crop, increasing the potential for frost damage and a delayed harvest. It may be necessary to irrigate in the spring for the crop to germinate. Unless soils are very heavy, a light irrigation of 15 to 20 mm (0.6 to 0.8 in.) prior to seeding is preferred to irrigation after seeding which can cause crusting and cooling of the soil.

Seed Varieties

Flax belongs to the genus Linum, one of 10 genera in the family Linaceae. The genus contains more than 100 annual and perennial species. Cultivated flax belongs to the species L. usitatissimum, and its varieties are of two types:

  • Oilseed flax, grown for oil
  • Fiber flax, grown for fiber

Oilseed Dominance and Fiber Revival

In Canada, at present, oilseed flax is the main commercially produced crop. But there is a growing trend back to natural fibers for both industrial applications and textiles. This trend will only continue as pressures increase to produce materials that are recyclable or decomposable.

As a result, Western Canadian businesses are realizing the value of flax straw, and are developing technologies to handle oilseed straw and produce fiber from it for industrial purposes. The extraction and processing of fiber from existing flax straw residue and the dedicated planting of fiber flax will create new production and value-adding opportunities for Western Canadian flax producers.

Breeding Programs in Canada

Flax and solin breeding is primarily driven by three major programs:

  • Agriculture and Agri-Food Canada – Morden Research Centre, Manitoba
  • Crop Development Centre – University of Saskatchewan, Saskatoon
  • Agricore United – Also at Morden Research Centre

Disease resistance to rust and wilt has been emphasized by all the programs in order to keep these problems under control. Thus, all registered flax and solin varieties are resistant to rust and must have moderate resistance to fusarium wilt. Since 1973, when the last outbreak of rust occurred, the resistance to flax rust has continued to hold.

Seed Types and Oil Composition

All flax varieties registered in Canada are brown-seeded and have high levels of alpha-linolenic fatty acid (ALA). Solin varieties, with less than 5% ALA, produce polyunsaturated edible oil similar to sunflower oil and, in Canada, must have yellow seed. Unregistered yellow-seeded flax varieties, with high levels of alpha-linolenic acid, are grown under contract for use in edible products and for the health food market.

Agriculture and Agri-Food Canada Program

Early Flax Breeding in Canada

Since the early 1900s, Agriculture and Agri-Food Canada and its predecessors have been active in developing new flax varieties for Canada and, in particular, for the Canadian Prairies. The initial program at the Central Experimental Farm in Ottawa produced varieties such as Diadem, Ottawa 770B, Ottawa 829C and Novelty.

Mid-Century Developments

During the 1950s, this program was particularly active, releasing varieties such as Linott, Raja and Rocket. The 1950s and 1960s also marked the beginning of an evolution and transition in flax breeding in Canada as a new program was initiated at the Indian Head Experimental Farm and the Winnipeg Cereal Breeding Laboratory, which led to the development of the variety Cree. As well, in Alberta, in the 1960s, a breeding program was conducted at the Fort Vermillion Experimental Farm and Beaverlodge Research Station, producing the variety Noralta, the predominant variety grown in northern Alberta and Saskatchewan.

Program Consolidation and Relocation

The breeding programs were eventually consolidated and moved to Winnipeg in 1960, finally moving to Morden, Manitoba where they still exist. The varieties Dufferin, McGregor, NorLin, NorMan, AC Linora, AC McDuff , AC Emerson, AC Carnduff and AC Lightning have been released by the Morden Research Centre.

Current Breeding Focus

The focus of the breeding efforts at Morden has been to develop improved flax cultivars for the Prairies.Consequently, most of the cultivars developed have wide adaptation to prairie conditions. The breeding program is currently focused on developing new cultivars with:

  • Increased yield potential
  • Decreased time to maturity
  • Better lodging resistance
  • Chlorosis tolerance
  • Improved disease resistance
  • Improved seed quality by increasing seed oil content and ALA content

Crop Development Centre

A modest breeding program was carried out at the University of Saskatchewan from the 1920s through the 1960s, which produced the varieties Royal and Redwood 65. The program was enlarged in 1974 when the Crop Development Centre (CDC) initiated a flax breeding program. It has since produced seven cultivars: Vimy, Somme, Flanders, CDC Normandy, CDC Valour, CDC Arras and CDC Bethune. Other varieties produced at the Crop Development Centre include Andro (tissue-culture-derived) and CDC Triffid (first transgenic flax cultivar). Both of these varieties have now been deregistered and are not commercially available.

The breeding program is developing varieties for Western Canadian conditions, with particular emphasis on Saskatchewan. Improved yield potential, earlier maturity, good agronomic performance, disease resistance, quality characteristics, greater seed weight and lodging resistance are some of the breeding objectives.

Crop Production Service

In 1987, a solin breeding program was initiated by Biotechnica Canada in cooperation with Australia’s Commonwealth Scientific & Industrial Research Organisation to develop low ALA flax, subsequently known as solin. In 1990, United Grain Growers Ltd. (UGG) purchased Biotechnica’s interest in the program and moved the program from Calgary to the Agriculture and Agri-Food Canada Morden Research Centre and the UGG research and evaluation farm at Rosebank, Manitoba. This breeding program has produced the solin cultivars, LinolaTM 947, 989 and 1084.

Overall the program is committed to the development of varieties with superior agronomic performance and disease resistance as well as enhanced quality (value) characteristics.