Effects Of Environmental Factors On Seed Color And Related Quality Characters Of Yellow-Seeded Rapeseed (Brassica Napus L.)

Yellow-seeded rapeseed (Brassica napus L.) is characterized with thinner seed coat and lower hull percentage, which in turn is correlated with higher oil, protein and lower crude fiber contents compared to black-seeded rapeseed from the same genetic background. The breeding of yellow-seeded rapeseed has become one of the main objectives in rapeseed breeding. However, it is hard for breeders to select effective lines due to the genetic instability of seed color in yellow-seeded rapeseed (Brassica napus L.).Many studies show that effects of environmental factors on crop quality are significant. So it is very important to study the effects of different environments on seed color and other related quality characters systematically.Some different environmental factors including the location, the major nutritious elements (N, P, K), planting density, sowing date, harvesting date, plant growth regulators, plant exogenous hormones and the techniques of drying were considered. The effects of the single environmental factor and the combinations of the various environmental factors on seed color and related quality characters in yellow-seeded rapeseed (Brassica napus L.) were studied. The correlation among the main quality characters of the same genotype and the stability of the seed color and other related quality characters of eight yellow rapeseed genotypes were also studied. The main results are as follows:The effect of the location on seed color of yellow-seeded rapeseed was studied in this paper. It was shown that the latitudes affected the seed color of yellow-seeded rapeseed significantly. The yellow-seeded degree of yellow-seeded rapeseed increased with rising of the latitude. It can be concluded that the pigments in seed coat were synthesized less in high latitude areas than in low latitude areas.The result of the quadratic regression orthogonal gyration combination design showed that high nitrogenous fertilizer level (300kg N /ha) increased the yellow-seeded degree and reduced the oil content of seed. It can be concluded that the synthesis of both the pigments and the fat had been affected by the nitrogenous fertilizer level. The oil content of seed increased with the applying of nitrogen and phosphorus when nitrogenous fertilizer was lower than 131.25kg N /ha and phosphate fertilizer was lower than 140.625kg P2Os /ha. If theyexceeded the limits, the oil content of seed would decrease with the applying of them. When nitrogenous fertilizer was in the level of 112.5kg N /ha and phosphate fertilizer was in the level of 140.625kg P2O5/ha, the oil content of seed could be increased nearly 8%. The effect of potassium on the oil content of seed in yellow-seeded rapeseed was little, but the oil content of seed increased with the applying of potash fertilizer when phosphate fertilizer was in high level. Although the protein content of embryo in most genotypes in the experiment increased with the applying of nitrogenous fertilizer, a few genotypes' protein content of embryo decreased with the applying of nitrogenous fertilizer. The effect of phosphorus on the protein content of embryo in yellow-seeded rapeseed was tiny. The protein content of embryo was inhibited when potash fertilizer was in low level, but it was promoted when potash fertilizer was in high level.It can also be concluded that the effects of planting density on seed color and oil content of seed in yellow-seeded rapeseed was different among the genotypes. High planting density led to the increase of yellow-seeded degree and oil content of seed in some genotypes, but it led to the decrease of them in other genotypes. The effect of planting density on the protein content of embryo was negative. That is the protein content of embryo decreased with rising of the planting density.The experiment of sowing date showed that the sowing date affected the yellow-seeded degree significantly. The yellow-seeded degree of yellow-seeded rapeseed increased before it decreased with the postponement of sowing-date. Earlier sowing contributed to the im...