Effect of sowing date on oil, protein and glucosinolate concentration of winter oilseed rape (Brassica napus L.)

P. Lääniste, V. Eremeev*, E. Mäeorg and J. Jõudu

Estonian University of Life Sciences, Kreutzwaldi 1, EE 51014 Tartu, Estonia *Correspondence: vyacheslav.eremeev@emu.ee

Abstract:

The effect of time of sowing on oil and meal quality of winter oilseed rape (Brassica napus L. cv. Express) was investigated at the Institute of Agricultural and Environmental Sciences of the Estonian University of Life Sciences in the period of 2001–2005. The rape seeds were sown at weekly intervals on four different dates: 8th, 15th, 22nd and 29th of August. The study shows that sowing date and environmental conditions affect the seed quality of winter oilseed rape. Early sown oilseed rape plants were more adapted to stressful conditions associated with high or low temperatures. The seeds of such plants had higher oil concentration (up to 50.2%) and a lower protein concentration (approximately 19%). Plants sown in late August were less tolerant to stressful conditions and their seed oil concentration was lower (47–48% DM). Oil and protein yield were higher in the early sown crops because the seed yield was higher. Also the glucosinolate (GSL) concentration of the seeds was affected by the time of sowing and weather conditions. Shortage of rainfall before harvest increased the GSL concentration in the seeds. Plants sown in late August did not tolerate the extreme environmental conditions and their seed glucosinolate concentration appeared to increase.

Key words:

cv. Express, glucosinolate concentration, oil concentration, oil yield, protein concentration, protein yield

Yields in vetch-wheat mixed crops and sole crops of wheat

R. Lauk and E. Lauk

Institute of Agricultural and Environmental Sciences; Estonian University of Life Sciences, Kreutzwaldi St. 64, 51014 Tartu, Estonia; e-mail: ruth.lauk@emu.ee

Abstract:

Field trials with common vetch (Vicia sativa L.) and spring wheat (Triticum aestivum L.) mixes were conducted from 1994 to 2004 on pseudopodzolic moderately moist soils in the trial fields of the Institute of Agricultural and Environmental Sciences of the Estonian University of Life Sciences at Eerika, outside Tartu (58^o 23´ N, 26^o44´ E). The results of the research showed that in cases where the yields of post-cereal wheat monocultures were 1500–3000 kg ha^-1 vetch-wheat mixed crops (at the seed densities of 50 germinating vetch seeds and 250 germinating wheat seeds per m²) guaranteed an approximate harvest of 3000 kg ha^-1, even under no nitrogen fertilisation, provided the total amount of precipitation in the growth period was 300 ± 50 mm. If the yields of monocultural wheat topped the level of 3000 kg ha^-1, mixed crops, however, lost their advantage over wheat monocultures as the latter’s grain harvests were greater in those cases. Vetch-wheat mixed crops maintained their advantage over sole crops of wheat insofar as protein yields were concerned, primarily due to the high protein content of vetch. The extra gain in the protein yields of mixed crops compared to wheat monocultures was 100–500 kg ha^-1 in our study, and was heavily dependent on the protein levels monocultural wheat was able to produce in each particular case.

Key words: