Nyt fra Danmarks JordbrugsForskning

Inden for de dyrkningstekniske forsøg i græsfrøavl er aktiviteterne for øjeblikket samlet omkring efterårsbehandlinger, snitning af frøgræshalm, rækkedyrkningssystemer samt gradueret gødskning, og inden for økologisk frøproduktion fokuseres på hvidkløver. Flere af disse forsøg blev etableret i 1996/97, da frøforsøgene flyttede fra Roskilde til ForskningscenterFlakkebjerg, og de forsøg er nu under afslutning

Organic forage seed production in Denmark

Organic forage seed production in Denmark

Aktuelt nyt fra Danmarks JordbrugsForskning, 2001

Kvælstof er et værdifuldt næringsstof for opnåelse af et højt frøudbytte, men også i relation til justering af væksten i udlægsmarken. Desværre har mange frøavlere begrænset adgang til kvælstof – dels på grund af en kvælstofnorm, som er fastsat under den økonomisk optimale værdi og dels på grund af begrænset adgang til husdyrgødning på økologiske planteavlsbedrifter. I Forskningsprogram frøavl arbejdes med udvikling af en behovsbestemt gødningsstrategi for at opnå en bedre udnyttelse af den til rådighed værende kvælstofmængde. Imidlertid tyder igangværende forsøg på, at kvælstof findes i ’alternative kilder’ såsom frøgræshalm og grøngødningsafgrøder, men kan de udnyttes i frøavlen? En anden supplerende kvælstofkilde er en øget anvendelse af hvidkløver specielt i økologiske sædskifter – men kan der skaffes økologisk udsæd? I de følgende tre artikler præsenteres igangværende aktiviteter inden for disse områder ved Danmarks JordbrugsForskning (DJF)

Birth outcome in women with breast cancer

We investigated whether maternal breast cancer affects birth outcome in a nationwide cohort study of 695 births from 1973 to 2002 of women with breast cancer with respect to preterm birth, low birth weight at term, stillbirth and congenital abnormalities as well as mean birth weight, compared with the outcomes of 33 443 births from unaffected mothers. There was no excess risk of adverse birth outcome for the 216 newborns of women with breast cancer before pregnancy. Stratification by mother's treatment did not change the results. For 37 newborns of women diagnosed during pregnancy, the prevalence ratio (PR) of preterm birth was 8.1 (95% confidence interval (CI): 3.8–17). However, 10 of the 12 preterm deliveries among these women were elective early deliveries. Among 442 births of women diagnosed in the 2 years from time of delivery, the PR of preterm birth was 1.4 (95% CI: 1.0–2.0), and the PR of low birth weight at term for boys was 2.9 (95% CI: 1.3–6.3). Overall, our results are reassuring regarding the risks of adverse birth outcome for breast cancer patients

Path and Ridge Regression Analysis of Seed Yield and Seed Yield Components of Russian Wildrye (Psathyrostachys juncea Nevski) under Field Conditions

The correlations among seed yield components, and their direct and indirect effects on the seed yield (Z) of Russina wildrye (Psathyrostachys juncea Nevski) were investigated. The seed yield components: fertile tillers m-2 (Y1), spikelets per fertile tillers (Y2), florets per spikelet- (Y3), seed numbers per spikelet (Y4) and seed weight (Y5) were counted and the Z were determined in field experiments from 2003 to 2006 via big sample size. Y1 was the most important seed yield component describing the Z and Y2 was the least. The total direct effects of the Y1, Y3 and Y5 to the Z were positive while Y4 and Y2 were weakly negative. The total effects (directs plus indirects) of the components were positively contributed to the Z by path analyses. The seed yield components Y1, Y2, Y4 and Y5 were significantly (P<0.001) correlated with the Z for 4 years totally, while in the individual years, Y2 were not significant correlated with Y3, Y4 and Y5 by Peason correlation analyses in the five components in the plant seed production. Therefore, selection for high seed yield through direct selection for large Y1, Y2 and Y3 would be effective for breeding programs in grasses. Furthermore, it is the most important that, via ridge regression, a steady algorithm model between Z and the five yield components was founded, which can be closely estimated the seed yield via the components

Intercropped green manure legumes in perennial ryegrass (Lolium perenne L.) for organic grass seed production

Results from field experiments in 2000 and 2002 showed that intercropping of perennial ryegrass and green manure legumes prolonged the time for nitrogen accumulation in the grass seed crop. The effect on the grass seed yield was dependent on the green manure legume species. However, using the intercropping technique it was possible to achieve seed yield at 1012 kg ha-1 in 2000 and at 829 kg ha-1 in 2000, which is very promising for the future organic seed production of perennial ryegrass

Grøngødningsafgrøder kan medvirke til et højt frøudbytte i økologisk dyrket almindelig rajgræs

Grøngødningsafgrøder kan medvirke til et højt frøudbytte i økologisk dyrket almindelig rajgræ

Effect of seed rate and row spacing in seed production of Festulolium

Establishment methods have proven to be of major importance for grass seed production. The objective of this research was to test the effect of different sowing techniques on plant establishment and the subsequent seed yield. Perennial ryegrass (Lolium perenne L.) is used as the model grass due to its large importance in Danish agriculture. In a three-year trial six different methods of under-sowing of perennial ryegrass in a spring barley cover crop were employed. Perennial ryegrass was either sown directly at different depths within the spring barley (Hordeum vulgare L.) rows or placed 2, 6 or 12 cm from the spring barley rows. Results of dry matter yield indicate that the best establishment of the grass occurred when placing the grass 6 or 12 cm from the cover crop row, and this is of importance in less vigorous grasses. Overall, no seed yield difference has been observed for perennial ryegrass when placing the grass 2, 6 or 12 cm from the cover crop row. Placement of the ryegrass seed crop 6 cm from the cereal row showed that a significant yield increase of 34-71 kg ha-1 can be obtained compared to sowing in the cereal row