Oil concentration in canola (Brassica napus L.) as a function of environmental conditions during seed filling period

Document Type : Research Paper


Agricultural and Natural Resources Research Center of Golestan, Postal code 4915677555, Beheshti Street, Gorgan, Iran


Oil concentration (OC) in canola (B. napus L.) is determined during seed filling
period (SFP), and the variation in OC is greatly related to environmental conditions
during that period. To determine factors affecting OC in canola, 12 field
experiments were conducted at Agricultural Research Station of Gonbad, Iran,
during 2000-07. The experiments were carried out under different growing
conditions. The regression functions were fitted to the data of each group of
genotypes, over years and experiments. Increasing SFP was a determinant factor
for increasing OC. Oil concentration was affected by the duration of SFP, which
was maximized when plants of both genotypes (open pollinates and hybrids) were
exposed to lower temperatures. There was a linear negative relationship between
air temperature during SFP and OC. High temperatures, accelerated the rate of
plant development, lowered the length of SFP, and reduced OC potential. In both
group of genotypes, the variation of OC was explained by rainfall during SFP, and
temperature and radiation interactions during the period, as showed by
photothermal quotient (PTQ). There was a positive logarithmic relationship
between PTQ during SFP and OC. The relationships of OC with duration of SFP,
and temperature, PTQ and rainfall during SFP over years, sowing dates and
genotypes showed that these variables are generally applicable in canola OC