Effect of sowing date on oil, protein and glucosinolate concentration of winter oilseed rape (Brassica napus L.)
Estonian University of Life Sciences, Kreutzwaldi 1, EE 51014 Tartu, Estonia *Correspondence: email@example.com
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.