| It was studied that the interaction between different fertilizer levels and density levels on growth period and process, biomass accumulation and distribution, physiological and biochemical metabolism, photosynthetic characteristics, economic characters, yield and quality of rapeseed, which were under the same fixed NPK ratio. The results showed:1. The impact on growth and biomassThe whole growth period of rapeseed extend with increase of fertilizer, while reduce augment of density. Fertilization played a more significant role than density. The whole growth period was averagely shortened 2 days when there was an increase of 2x104 plant/667m2 in density under the same fertilization treatments, while the increase 6kg/667m2 nitrogen extended 2.8 days.The plant height increased with the increase of fertilizer and density in seedling period, but decreased with density under poor fertilization, and got to the highest with the density 3x10 plant/667m2 and the nitrogen level above 9kg/667m2. Fertilization had positive affect on root collar diameter, stem leaf number, green leaves, while high density had negative effect. In the winter solstice period, stem green leaves with density 1x104, 3x104,5×104 plant/667m2 were 6.2,5.4,4.8 under 9kg/667m2 nitrogen, were 6.5,5.8,5.2 under 15kg/667m2 nitrogen, were 7.0,6.2,5.4 under 21kg/667m2 nitrogen, respectively.The effect of density on biomass of the whole pant, different organs, shoot parts were greater than fertilization. The biomass accumulation are simulated by Logistic model(S Curve), according to which it was showed that ultimate biomass averagely decreased 21.8g along with an increase of 2x104 plant/667m2 in density under the same fertilizer treatments; An increase of 6kg/667m2 nitrogen enhanced ultimate biomass by 10.5g under same density.2. The impact on physiological and biochemical metabolism and photosynthetic characteristicsSoluble sugar content and C/N decreased when fertilizer got augmented, increased when density got higher, both of with reached a peak on Jan.9. C/N increased by 2.73, 2.11,1.24 with an increase of 2×104 plant/667m2 in density when fertilizer level getting higher, decreased by 0.37,1.86,2.00 with an increase of 6kg/667m2 nitrogen when density getting higher, and reached the lowest in the flowering period maintaining 1.0%-2.9% among different treatments.The content of total nitrogen increased with fertilizer level, and decreased with density. Higher fertilizer level and lower density contributed to higher Chlorophyll SPAD and net photosynthetic rate. LAI,PAI,IPAR increased with fertilizer level or densi(?)y, which could be compensated by higher density when in relatively poor fertilization.3. The impact on yield and its componentThere was variable combination of density and fertilizer level to improve the yield of rapeseed. Maximum yield was obtained with density 2×104～3×104,3×104～4×104, 4x104～6x10,4x104～2x104 plant/667m2, corresponding with nitrogen application amount 0～3,3～9,9～18,18～24kg/667m2, respectively. Nitrogen application amount had a significant effect to improve plant height, while less positive impact on stem diameter, main inflorescence length, branches location of stem, the numbers of the effective branches and pods than density. The number of the effective branches and pods average ly reduced 1.44 and 64.47 with every increase of 104 plants, respectively.More fertilizer amount resulted in more distinction on effective branches and pods among different density treatments. The numbers of effective branches and pods with 5x104 plant/667m2 density were respectively more 17.48x104～20.7x104, 293.08x104～466.73x104 than that of 1x104 plant/667m2 density under different fertilizer levels, and with 21kg/667m2 fertilizer were respectively more 2.53x104～6.15x104,122.28x104～206.50x104 than that of 9kg/667m2 fertilizer under different density.When in the same fertilizer conditions, more late the sowing time or lower nitrogen level was, more stimulating influence the high-density treatment respectively made. Yield could reach more than 200kg/667m2 if application amount was 18kg/667m2 and density was 4x104/667m2 when sowed on October 30. The main economic characters and yield components among different treatments reduced with later sowing time, which were more effectively determined by density not fertilizer level under same sowing time.4. The impact on quality of rapeseedRapeseed from branches had lower oil content and higher contents of protein or glucosinolates than that from main stem, of which glucosinolates content (29.32μmol/g) was 56.79% higher than that from main stem (18.70μmol/g). There would be a fall in the content of oil and an increase of protein and glucosinolate in rapeseed when the amount of fertilizer is raised. While the density is increased, there would be an increase in oil content and a fall in protein and glucosinolate of main stem and branches, but a fall in the glucosinolate content of the whole plant. |
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