Oil and protein contents in rapeseed (Brassica napus L.) as a function of environmental conditions during seed filling period

Abstract

Rapeseed (Brassica napus L.) is the third most important oilseed crop in the world, after palm and soybean, and is an excellent raw material for edible oil and biodiesel production. It is one of the most important plants of Brassicaceae family which its seed contains more than 40% oil and its meal is reach in protein. Oil belongs to a group of semi-drying oil with iodine value 95-120. It is used in nutrition and for technical purposes. Meal from rapeseed after oil extraction provides a protein rich animal feed. Many studies reported that the quality of rapeseed greatly influenced by the water stress occurred from flowering up to the ripening of seeds and under water stress condition the varieties that are capable of maintaining much more water would have more seed yield and consequently more oil content. In this study we used a multi-year results (2007-2018) the quality of rapeseed as a raw material for the further processing, obtained from the company Victoriaoil, Sid. In order to determine the association between seasons and meteorological indicators, precipitation, temperature (minimum, maximum and mean) were analyzed during each growing season. Based on these data for each meteorological parameter were calculated three variables corresponding to the months of the vegetation period of the rapeseed. PCA analysis was done on a set of meteorological indicators and the content of oil and protein in grain, after which a biplot from the first two PCA axes was constructed in order to visualize the association between the season, grain quality and meteorological indicators. According biplot, there was a close relationship between oil content and precipitation during the month of April. Also, the precipitation in May is in a positive association with the oil content, while the rainfall in June was not related to this trait. On the other hand, there was no clear association between the temperatures in May and the protein content, which is probably the result of low temperature variations in May during the four studied years. Then again, the association of protein content with meteorological indicators was analyzed during the last 4 years (2014-2017), with the first PCA axis explaining 45.82% and the other PCA axis 40.93% of the variability. Weather conditions had a significant impact on the content of oil and protein in grain during the growing rapeseed season, especially temperature and precipitation.