Radiation use by oil seed crops - a comparison of winter rape, linseed andsunflower

For the production of grain crops rich in oil, winter rape, linseed and sun flower are similarly suitable at many arable locations. We wanted to compar e the extent to which radiation (PAR) is intercepted and utilized by the in dividual species for dry matter and yield production. For this purpose, a 2 -year field experiment comprising the factors genotype, N fertilization and soil tillage was conducted. For five phases of crop development, growth ra tes (CGR, RGR and NAR) and PAR utilization were calculated. At full ripenes s, total dry matter, grain, oil and energy yields, the crop- and year-speci fic PAR supply, its interception and utilization for dry matter production and the resulting energy binding were determined. Due to the different indi vidual vegetation periods, the PAR supply of the crops differed. The crop a ssimilation areas also differed, with values for winter rape and sunflower higher than those for linseed. The yield productivity of winter rape and su nflower was also higher than that of linseed. N fertilization increased yie ld to different extents for the different crops. On average, winter rape an d sunflower produced the same amounts of dry matter and energy yield. Due t o a higher harvest index, sunflower had the highest grain yield, and becaus e the oil concentration in grain was comparatively high sunflower produced the highest oil yield, too. Under cool and wet climate conditions, however, the productivity of sunflower is offset by a relatively high yield risk be cause of uncertain ripening. The highest PAR utilization by linseed did not compensate for its very short vegetation period in combination with the lo west PAR interception.