Studies On Main Nutritional Characteristics And The Formation And Regulation Of Yield And Quality In Yellow-seeded Rapeseed (Brassica Napus L.)

Oilseed rape (Brassica napus L.) is one of the most important oil crops in the world. A large number of evidences had shown there were many differences of quality characters between brown or black-seeded and yellow-seeded rapeseed. 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. Breeding for yellow-seeded rapeseed cultivars with good agronomic characteristics has become one of the main objectives in rapeseed breeding. By intensive breeding for many years, several yellow-seeded cultivars (Brassica napus L.) have been developed and used in rapeseed production recently. In recent years, great attentions have been paid to the formation and genetic mechanism of its seedcoats' characters and quality characteristics of seeds, while little have been known about the nutritional characteristics and the formation and regulation of yield and quality in yellow-seeded rapeseed (Brassica napus L). In this study, four pairs of near-isogenic lines of rapeseed (B. napus L.) [designated L1 (yellow-seed) and L2 (black-seeded), L3 (yellow-seed) and L4 (black-seeded), L5 (yellow-seed) and L6 (black-seeded), L7 (yellow-seed) and L8 (black-seeded)] had been used as the experimental materials to study the nutritional characteristics and nutrient efficiency of yellow-seeded rapeseed (Brassica napus L.).Its characteristics and physiological mechanism of yield and quality formation were also discussed. To confirm the results of above experiments, quadratic regression orthogonal gyration combination design was used to study the effects of density, nitrogen, phosphorus, potassium and boron on the yield and quality characters of "Yuhuang NO.2". The main results were shown as following:1. Nutrient contents and accumulation of yellow-seeded and black-seeded rapeseed (Brassica napus L.) plant were measured at different stages. The results were shown as follows: The contents of nitrogen and phosphorus were the highest in the seedling stage and with the development of the plant the contents of N and P declined gradually. The content of nitrogen in YS was lower than that in BS at seedling stage and overwintering stage but higher than that in BS since BBS. The content of phosphorus in aboveground parts of YS was 1 to 12% higher than that in BS. Potassium mainly distributed in pericarp and a little in seeds. Boron content in YS was lower than that in BS at flowering stage but as much as that in BS at maturity stage for strong transportation of boron in YS. The accumulation amount of N, P, K elements in YS were superior to those in BS and the proportion of N and P in seeds were more in YS than in BS.2. With low N application the contents of boron in seeds declined significantly and the nutrient accumulation in aboveground parts of YS decrea(?) much more than that of BS. Phosphorus contents in stem and seeds of YS decrea(?) much more than that of BS with low P application but the content of phosphorus of ,(?)carp and the accumulation of nitrogen and phosphorus in YS decreased less than tho(?) in BS. With low B application the proportion of N declined in stem and pericarp but increased in seeds, and YS didn't increase so rapidly as BS. Those meant the transportation of boron was far stronger in BS than in YS.3. Lynch's model was used to appraise the nutrient efficiency of the rapeseed (Brassica napus L.) genotypes. The results showed that there were significant differences in N, P, B efficiency among the tested rapeseed genotypes. Based on N efficiency, L1 and L8 were inefficient and nonresponsive; L2 was high efficient but nonresponsive; L7 was inefficient but responsive. Based on P efficiency, L1, L3 and LS were high efficient and responsive while L2, L4 and L6 were inefficient and nonresponsive. Based on B efficiency, L3 and LS were high efficient and responsive; L1 was inefficient and responsive; L2, L4 and L6 were inefficient and nonresponsive. Nitrogen uptake efficiency and nitrogen utilization efficiency were significantly correlated with yield, but nitrogen uptake efficiency contributed to yield more. With low P application phosphorus uptake efficiency contributed to high plant yield while phosphorus translocation efficiency was more important for high plant yield with normal P application. Boron uptake efficiency was the most important one for high plant yield among three nutrient indexes and boron utilization efficiency was the next, while the boron translocation efficiency was the last one. Compared to BS, ANRE, PNUE and PFPAN of YS were higher but SNDR was lower significantly. PFPAP, PFPAB, PBUE and SBDR of YS were higher than those of BS.4. Two pairs of different genetic near-isogenic lines of yellow-seeded and black-seeded rapeseed (Brassica napus L.) genotypes were used to study the physiological characters of yellow-seeded rapeseed in seedling stage, which included photosynthetic characters, characters on C/N metabolism and accumulation of dry matter. The results showed that the chlorophyll content and carotenoid content of yellow-seeded rapeseed were higher than those of black-seeded rapeseed, but its net photosynthetic rate and the leaf area index (LAI) were lower compared to black-seeded rapeseed from the same genetic background. It was found that there were higher soluble sugar content and lower protein content in yellow-seeded rapeseed plants than in black-seeded rapeseed plants in every plant organs during seedling stage, and there were lower nitrogen content and activity of nitrate reductase in yellow-seeded rapeseed plants than in black-seeded rapeseed plants at overwintering stage. Width of root colla and dry matter per plant in yellow-seeded rapeseed plants were also lower than those in black-seeded rapeseed plants, indicating the weak growth vigor of yellow-seeded rapeseed. The amount of dry matter accumulation in YS had exceeded that in BS significantly since BBS and the harvest index of YS was also higher than BS's.5. The length of siliqua approached the greatest value on the 15^th day after anthesis while the width and surface area of siliqua approached their greatest values on the 24^th day. The length and width of siliqua both declined a little with its maturity. There were the similar developmental regularities of siliqua in YS and in BS but the average length and surface area of YS's siliqua were significantly higher than those of BS's. There was no significant difference between the average widths of YS's siliqua and that of BSY's. The maximal accumulation intensity of siliqua dry matter and output intensity of pericarp were both stronger in YS than in BS. LAI after anthesis, pigments content in leaves at EFS, PAI and pigments content in siliqua at MAS were all higher in YS than in BS. There was no significant difference between the net photosynthetic rate of YS's and that of BS's in initial and maturity stage of siliqua development but the net photosynthetic rate of YS's was higher than that of BS's significantly during the 17^th to 31^th day after anthesis.YS had high soluble sugar content, high amylase activity, high SPS activity and high GS activity in pericarp, which meant enough sucrose and strong assimilative intensity in pericarp of YS. There was higher SS activity in YS seeds than in BS seeds, which meant there were more sucrose to be used in "sink" and more oil and protein to be synthesized and accumulated in BS seeds. With the development of the siliqua, the activities of CAT and SOD, which belonged to the protective enzyme system of pericarp, decreased and the MDA content increased gradually, especially 17^th day after anthesis. There were higher activities of CAT and SOD and lower content of MDA in YS pericarp than in BS pericarp, which led to the lower process of pericarp senescence in YS.6. YS and BS that derived from the same genetic background were compared in terms of some characteristics related yield. The results showed that coefficients of variation of YMR and siliqua morpha were higher in YS than in BS. As far as coefficients of variation of NSSMR and WAMR were concerned, no apparent difference was found between YS and BS. Coefficients of variation of NSSPB, WSPB, VSPB, SASPB, YSB and NSASB were all higher in YS than in BS. Correlation and pathway analysis showed that the main agronomy characters, which affected the yield per YS plant, were PPB, NSAPB, and NSASB while the main agronomy characters that affected the yield per BS plant were NSASB, PH and NPBA.7. Dynamic changes of oil content and the components of fatty acids were studied in different developmental stages of YS as comparing with those of BS. The results showed that there was the similar regularity of oil accumulation in YS and BS, but the speed of oil content accumulation of YS was significantly faster than that of BS since 24^th day after anthesis and the oil content of YS was 3% higher than that of BS in MAS. The maximal accumulation intensity of oil content, which approached their greatest values on the 30^th day after anthesis, was stronger in YS than in BS. The contents of palmitic acid and linoleic acid reached their peaks during the period of seed forming and then declined gradually with the development of the seeds while the content of oleic acid reached its pear on 31^th day after anthesis and then decreased rapidly. The content of linolenic acid declined during 17^th to 31^th day after anthesis and maintained 11% or so. The content of eicosenoic acid was about 1% on the 17^th day after anthesis and increased sharply after that until it was reached around 10% on the 45^th day after anthesis. The content of erucic acid increased in the whole developmental stage and reached its peak at maturity. There were similar regularities in the variations of components of fatty acids in YS and BS. Not only the oil content of YS was much higher than that of BS, but also the composition of fatty acids were quite different between them. The erucic acid content in YS was much lower and the linoleic acid and eicosenoic acid were higher than that of BS significantly.8. Correlation analysis among the main quality characters of the tested rapeseed genotype indicated that PCOS was significantly negatively correlated with OCOS and there were highly significantly positive correlation among contents of palmitic acid, oleic acid and linoleic acid, but they were (highly) significantly negatively correlated with the content of erucic acid. As for BS, palmitic acid, oleic acid and linoleic acid were highly significantly negatively correlated with linolenic acid, but they were highly significantly positively correlated with eicosenoic acid. As for YS, above three fatty acids were nonsignificantly positively correlated with linolenic acid, but they were highly significantly negatively correlated with eicosenoic acid. Linolenic acid was highly significantly negatively correlated with eicosenoic acid and highly significantly positively correlated with erucic acid in BS, while there were no apparent correlations among contents of Linolenic acid, eicosenoic acid and erucic acid in YS. The correlation between eicosenoic acid and erucic acid in YS was different from that in BS. The relationship between the main quality characters and agronomy characters of siliqua was mainly due to the correlation between eicosenoic acid, erucic acid, palmitic acid, linoleic acid, oleic acid and LS, NSS, SAS, LSB. OCOS in MAS was significantly positively correlated with the content of pigment in pericarp at TFS and highly significantly positively correlated with the contents of Chl-a and Chl-(a+b) in seeds.9. The changes of the main quality characters of rapeseed (B.napus L.) under low nutrient application condition and the differences between YS and BS were also studied. It was shown that low nitrogen application improved the OCOS and inhibited the synthesis of protein. The contents of sumop of L1, L7 and L8 were high but that of L2 was low whenever nitrogen was applied or not. Nitrogen application affected the contents of palmitic acid and linolenic acid significantly. Under low nitrogen application condition the content of palmitic acid in YS increased a little or not, but that in BS declined in a degree. The content of sumop in YS was affected by low phosphorus less but was sensitive to low boron application. The content of sumop of YS was higher than that of BS significantly whenever phosphorus and boron were applied or not. Phosphorus, boron and their interaction affected the contents of linoleic acid, linolenic acid and eicosenoic acid (highly) significantly but effects of them on palmitic acid, oleic acid and erucic acid were nonsignificant. Low boron application improved the content of palmitic acid in YS but reduced in BSY.10. Quadratic regression orthogonal gyration combination design was used in the study to investigate the effects of fertilizers and plant density on the characters of the main raceme and branch, as well as yield in "Yhuang NO.2". The results indicated that the LMRA was mainly affected by plant density and nitrogen, but the interaction of nitrogen and boron was also concerned. The VSMR increased with the amount increase of nitrogen and the effects of other four facts were small. Morpha characters of the main raceme were mainly affected by plant density, nitrogen and phosphorus, and the influence of potassium and boron was relatively little. PPA of the main raceme, which was affected by the interaction of plant density and potassium, was somewhat concerned with plant density and fertilizer, especially with nitrogen fertilizer. The interaction of nitrogen and phosphorus was concerned with the SNPA of the main raceme that was mainly affected by boron. The effect of plant density on CYMR could be fitted with parabola at zero levelThe interactions of plant density and phosphorus, of nitrogen and phosphorus and of nitrogen and boron on VSPB, which increased with the increase of nitrogen amount applied and plant density, were significantly positive. The main effects of phosphorus and potassium on NSSPB, which ranged first and second respectively among the five factors, were negative. The interaction of plant density and potassium on NSSPB was significantly positive. WSPB was primarily affected by nitrogen and the interactions of plant density and phosphorus, of nitrogen and phosphorus and of nitrogen and boron, which were positive. The effect of plant density on LSPB could be fitted with parabola and phosphorus on it was negative. Interaction of plant density and potassium was also concerned with LSPB. The effect of plant density on NSAPB was positive, which the effect of nitrogen on could be fitted with parabola at the zero level. The effect of nitrogen on PPB was highly significantly negative, but effects of plant density and phosphorus were positive. There were no apparent effects of potassium and boron on PPB. The effect of nitrogen on NPBA could be fitted with parabola and the effects of boron and plant density on it were negative. NCPBA was mainly affected by plant density and was secondly affected by nitrogen. The interaction of plant density and nitrogen was also connected with NCPBA. The main effects of nitrogen and plant density on CYPB were positive and the effect of potassium on it could be fitted with parabola. There was obvious mutual effect between plant density and boron, and the interaction of phosphorus and potassium on CYPB was significantly positive. Nitrogen was the most important factor among the five tested factors, which affected the NSBA and NCSBA. Nitrogen and phosphorus were both significantly correlated with NSASB.Based on the yield of seeds more than 2178.06 kg/hm², the optimum cultivation model under tested soil condition for "Yuhuang NO.2" was as following: plant density 11.66～11.99×10⁴, N 201.60～211.58 kg, P₂O₅ 115.20～124.80 kg, K₂O 115.80～124.20 kg and B 1.49～1.61 kg per hm². Effects of the factors on the yield of seeds in our experiment were nearly consistent with those on CYPB and BYC. That maybe indicated that CYPB was affected by the tested factors directly and the yield of seeds and BYC were affected indirectly.11. Quadratic regression orthogonal gyration combination design was used in this study to investigate the effects of fertilizers and plant density on the main quality characters including OCOS, oil yield, and the components of fatty acids as well as pigments in seeds of "Yuhuang NO.2". The results showed that the effect of nitrogen on OCOS ranged first among the five factors. The OCOS declined significantly with the increase amount of nitrogen. The effect of nitrogen on OCOE of the main raceme could be fitted with parabola and the interaction of plant density and nitrogen and plant density and phosphorus affected the OCOE of the main raceme significantly.Based on the oil yield more than 940.80 kg/hm², the optimum cultivation model under tested soil condition for "Yuhuang NO.2" was as following: plant density 11.82～12.15×10⁴, N 197.10～207.53 kg, P₂O₅115.08～124.92 kg, K₂O 115.80～124.20 kg and B 1.51～1.63 kg per hm². Effects of the factors on oil yield in our experiment were similar with those on yield of seeds . That maybe indicated that the high yield of seeds was the foundation of getting high oil yield.The effects of boron, phosphorus and potassium on palmitic acid, oleic acid and linoleic acid respectively all could be fitted with parabola. The effects of nitrogen and phosphorus on linolenic acid also could be fitted with parabola, and the interactions of plant density and potassium and phosphorus and boron affected linolenic acid too. The content of eicosenoic acid increased gradually with the amount increase of phosphorus. There was no apparent influence of plant density and fertilizer on the content of erucic acid, which was determined by genetic source.The effect of nitrogen on the content of chl-a in seeds ranged first among all the factors tested. Increase of the nitrogen amount applied could improve the content of chl-a in seeds. Content of chl-b in seeds was mainly affected by nitrogen and boron, but there was almost no significant influence of plant density and fertilizer on the content of chl-(a+b) that may be determined by genetic background. The effect of nitrogen on the content of carotenoid in seeds was positive.