Lars T. Havstad

Research Scientist

(+47) 906 76 435
lars.havstad@nibio.no

Place
Landvik

Visiting address
Reddalsveien 215, 4886 Grimstad

To document

Abstract

Different sowing methods and sowing rates were evaluated in organic seed production of timothy (two trials), meadow fescue (two trials) and red clover (one trial) in Southeast Norway, during 2010–2013. The plan included: (1) broadcast sowing of grass/clover, cover crop sown at 12 cm row distance; (2) sowing of cover and seed crop in crossed rows, both at 12 cm row distance; and (3) sowing of cover crop and seed crop in every other row. The three sowing rates were 5, 10 and 15 kg ha−1 in timothy and meadow fescue and 3, 6 and 9 kg ha−1 in red clover. On average for sowing rates and all trials with timothy, meadow fescue and red clover, first year’s seed yields were 5–6%, 20–25% and 19–25% higher on plots sown with cover crop and seed crop in every other row than on plots where seed crop had been broadcast or sown perpendicularly to the cover crop. The different sowing methods had no effect on weed coverage or weed contamination in the cleaned seed. Increasing sowing rate usually had a negative influence on seed yield, while weed coverage/contamination was not significantly affected. It is concluded that organic seed crops should be established with cover crop and seed crop in every other row at a low sowing rate. However, in an organic production system, even this favorable method will not always be sufficient to meet the requirement for seed crop purity.

Abstract

The market for herbage seed straw has diminished in many seed-production areas due to less livestock. Seed growers are therefore looking for alternatives to straw removal, which up to now has been the most common practice. During 2000–2006, different alternative straw chopping methods, both at the back of the combiner and with a tractor-mounted flail-chopper, and field burning strategies were evaluated in seed crops of timothy (Phleum pratense) and meadow fescue (Festuca pratensis) in southeast Norway. The requirement for an extra N input in autumn (30–40 kg ha-1) when practising straw chopping was also examined. Compared to straw removal, straw chopping at the back of the combiner during seed harvest did not reduce seed yield in the following year as long as stubble height was low (<10 cm in timothy) and the straw spread uniformly in the field. On average, seed yield was 1–4% and 1–9% higher compared to straw removal in timothy and meadow fescue, respectively. If the chopped straw was spread unevenly, or long stubble was left at combining, it is recommended to use a tractor-mounted flail-chopper after harvest. The experiments did not provide any support for an extra input of nitrogen in autumn, either in timothy or meadow fescue, when the straw was chopped rather than removed. Burning of stubble and straw soon after seed harvest was another efficient clean-up method after harvest, which increased seed yield 9–15% and 17–20% compared to straw removal in the two species, respectively. However, as the burning method is risky and causes smoke emissions, it is normally not recommended. It is concluded that for most seed growers, the most effective, least laborious and most environment-friendly alternative to straw removal will be to chop the straw at the back of the combiner during seed harvest.

Abstract

Norwegian agriculture is totally dependent on a safe supply of seed of winter-hardy timothy varieties. The annual seed consumption varies depending on the extent of winter damages, particularly in northern Norway, and the average seed yield varies with weather and harvest conditions in the seed-producing districts in the southeastern and central part of the country. To buffer these variations, seed companies always keep stocks corresponding to 50-100 % of the average annual seed consumption. Such large stocks are risky to maintain as seed lots will loose germination over time. Our objective was to elucidate the effect of seed harvest time and seed storage location on the longevity of timothy seed. In 2003, timothy ‘Grindstad’ was combined directly on 2, 5 or 8 August corresponding to a seed moisture content (SMC) of 34, 27 and 20 %, respectively. After harvest the seed was dried to 10-11 % SMC. Germination analyses were accomplished 3, 15, 26 and 38 months after seed harvest; the three latter after splitting each seed lot into four sub-lots that were stored either in a conditioned seed store (4ºC, 30% RH), or in unconditioned warehouses at there climatically different locations. While seed harvest time had no effect on germination three months after harvest, differences became increasingly evident as time went by. After 38 months’ storage, seed stored in the conditioned store or in the warehouse at the continental location Tynset germinated, on average for harvest times, 15-16 units better than seed stored in the warehouse at the coastal location Vaksdal; and seed lots harvested at 20 % SMC germinated, on average for storage locations, 24 units better than seed harvested at 37 % SMC. While it has long been documented that direct combining at high SMC may damage seed germination, there has been less awareness that this damage may not manifest itself until after a certain storage period.

Abstract

Since the formation of the International Herbage Seed Group (IHSG, formerly IHSPRG) in 1978, International Herbage Seed Conferences have been organized, mostly at four year intervals. The Sixth Conference was held at Gjennestad Horticultural College in Vestfold, Norway, from 18 to 20 June 2007. As for other IHSG activities, the objective of the conference was ‘to encourage cooperation and communication between workers actively engaged in herbage seed production research’. About 80 delegates from 20 countries attended the conference. Four invited and almost sixty voluntary papers were presented, either orally or as posters. The topics were split into the following sessions: 1. Opening session with overview over herbage seed production and seed trade, world wide. 2. Herbage seed for the future: Biodiversity, GMOs and the role of seed yield capacity in herbage breeding programs. 3. Seed production of tropical species and species for stressful environments. 4. Physiological restraints to seed set and seed filling. 5. Establishing the potential for high and pure seed yields. 6. Fertility, plant growth regulators, and plant protection. 7. Statistical methods, seed harvest, and post-harvest issues.

Abstract

Tiller demography and contribution to seed yield were studied in first year seed crops of smooth bromegrass (SB, Bromus inermis ‘Lofar’) and meadow fescue (MF, Festuca pratensis ‘Salten’) planted on different dates and with increasing plant densities (A: 15 Jun. / 11 plants m-2, B: 15 or 30 July / 44 plants m-2, C: 15 August or 10 September /178 plants m-2) in field trials at Landvik, SE Norway. While the total tiller population in most crops increased until seed harvest, it decreased during panicle elongation in crops of SB and MF that had reached 2000 and 3500 tillers m-2 in early spring, respectively. Except for the fact that many of the primary tillers of SB died after producing barren stems, tillers formed in August and September had the greatest chance of becoming reproductive and produced the heaviest inflorescences in both species. Most tillers produced in winter or early spring either remained vegetative or died, but spring-emerging tillers contributed up to 30% of the total seed yield in early-established, low-density crops of MF. It is concluded that spring-emerged tillers contribute more to seed yield in MF than in SB and more in seed crops established early at low plant density than in crops established late at higher density.

Abstract

Different methods of straw residue management were evaluated in field trials with seed crops of timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) in SE Norway during 2000-2005. Compared to straw removal, which up to now has been the most common straw management practice in seed production of the two species, straw chopping and spreading at the back of the combiner during seed harvest did not reduce seed yield in the following year when stubble height was kept at a low level (preferably less than 10 cm). However, in order for newly developed tillers to rapidly penetrate the straw layer in autumn, the chopped straw had to be spread uniformly in the field. The experiments did not provide any support for an extra input of nitrogen in autumn, either in timothy or meadow fescue, when the straw was chopped rather than removed. In both species, also burning of straw and stubble soon after seed harvest was an efficient and fast clean-up method in the field after harvest. However, due to problems with smoke emission, especially near traffic roads and populated areas, field burning is not recommended as a preferable straw management method.