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Integrated Nitrogen Management Strategy for Winter Oilseed Rape (Brassica napus L.) in China     REN Tao, LU Jian-wei Scientia Agricultura Sinica   2016,49(18 ):3506 -3521. DOI:10.3864/j.issn.0578-1752.2016.18.005 Abstract  （563） HTML （8） PDF（pc） （637KB）（706） Save Oilseed rape is one of the predominant oil crops in China. Yangtze River Basin is the key winter oilseed rape production region in China, where the specific climatic conditions, soils and cultivation practices induce the different characteristics of soil nutrient supply, crop growth and nutrient demand. High crop yield, high economic benefit and high nutrient use efficiency are the determinants of agricultural production and sustainable development. Asynchrony between oilseed rape nitrogen (N) demand and soil N supply in space and time is the major reason that excessive N or deficient N input is the most important limiting factor of rapeseed yield and economic benefit. Optimal N fertilization is critical to achieve high seed yield and high N fertilizer use efficiency. In this paper, the authors reviewed the recent perspectives on oilseed rape N management, including crop N uptake, soil N supply, the critical N fertilizer application methods and the matching techniques. Further, considering the characteristics of crop growth and soil N supply, an integrated N management strategy, of which the key is “promotion in early and stabilization in late” to match crop N uptake and soil N supply, is put forward. The core content of the strategy includes (1) adjusting the timing and proportion of N fertilization and N sources to satisfy N requirement in the seedling period, focusing on soil N supply to promote N transfer and re-utilization since stem elongation period; (2) Depending on soil N supply under different rotations and/or crop straw incorporation, coordinating the distribution of N fertilizer in whole growing season; (3) Synergistic interaction with other practices including optimal plant density, fertigation, application with other nutrients and mechanization to obtain high seed yield and high N fertilizer use efficiency. Reference丨 Related Articles丨 Metrics

Effects of Different Cultivations and Nitrogen Application Methods on Seed Yield and Nitrogen Use Efficiency of Oilseed Rape (Brassica napus L.)     LIU Bo, LU Jian-wei, LI Xiao-kun, CONG Ri-huan, WU Li-shu, YE Chuan, ZHENG Wei, XU Wei-ming, YAO Zhong-qing, REN Tao Scientia Agricultura Sinica   2016,49(18 ):3551 -3560. DOI:10.3864/j.issn.0578-1752.2016.18.009 Abstract  （490） HTML （12） PDF（pc） （2279KB）（825） Save 【Objective】Field experiments were carried out to study the effect of different cultivations and nitrogen (N) application methods on seed yield and N use efficiency of oilseed rape (Brassica napus L.) in the main planting areas, and provide theoretical support for high efficient fertilization management in oilseed rape.【Method】 Field trials were conducted in Hubei and Jiangxi provinces during the period of 2010-2011. Three methods of N application (i.e., surface broadcast placement, plough placement, and concentrate placement) were taken to analyze the impact on rapeseed yield, dry matter accumulation and N uptake between the transplanted oilseed rape (Brassica napus L.) (TOR) and direct-sown oilseed rape (DOR).【Result】 Under the same processing conditions, the seed yield level of TOR was higher than DOR and the difference value was 299.1-544.2 kg·hm-2. The TOR could obtain higher biomass compared to DOR between aboveground and underground according to the dry matter dynamics, furthermore, N accumulation increased significantly by 33.1%-54.8% on average for TOR. Moreover, the agronomic efficiency (AEN) and N apparent recovery efficiency (REN) were significantly increased in TOR compared to the DOR, respectively, which AEN increased by 20.2% from 6.5 to 7.8 kg·kg-1, and REN increased by 37.5% from 27.6% to 37.5%. N application had a significant effect on seed yield, especially for TOR. Different N application methods resulted in a noticeable impact on yield, dry matter accumulation, N uptake and N use efficiency, following as concentrating> ploughing > broadcasting. The concentrating could increase yield and N accumulation compared to broadcasting, increased yield by 18.2%-23.8% and N accumulation increased by 19.0%-37.0% for TOR and DOR，respectively. Compared with broadcasting, the AEN of concentrating increased by 27.7% ranged from 6.9 to 8.8 kg·kg-1 and REN increased by 27.2% ranged from 33.3% to 42.3% in TOR, meanwhile, the AEN of concentrating increased by 31.7% ranged from 5.7 to 7.5 kg·kg-1 and REN increased by 50.7% ranged from 22.0% to 33.2% in DOR. The increase amplitude in underground biomass accounted for 61.8% under concentrating during the whole period and the aboveground portion was 50.5% compared with broadcasting for TOR, while it was 78.5% and 66.7% for DOR, respectively.【Conclusion】 The growth and yield formation were more sensitive to different N application methods in DOR. Dry matter accumulation including underground and aboveground part after anthesis can be coordinately achieved synchronous accumulative under Concentrating. Therefore, both Banding and Holing can efficiency during the oilseed rape production among all the N application methods. Reference丨 Related Articles丨 Metrics

Characteristics of Photosynthetic Nitrogen Allocation in Leaves of Different Positions in Winter Oilseed Rape at Seedling Stage Under Suitable Nitrogen Level     LIU Tao, LU Jian-wei, REN Tao, WANG Wei, WANG Zhen, WANG Shao-hua Scientia Agricultura Sinica   2016,49(18 ):3532 -3541. DOI:10.3864/j.issn.0578-1752.2016.18.007 Abstract  （477） HTML （1） PDF（pc） （1664KB）（811） Save 【Objective】 This study was carried out to investigate the effects of nitrogen allocation on the photosynthetic apparatus of leaves at different positions in winter oilseed rape under suitable nitrogen level at seedling stage and to analyze the limiting factors that affect the photosynthetic nitrogen use efficiency by nitrogen nutrition, and provide a theoretical basis for the reasonable application of nitrogen fertilizer.【Method】A field experiment was carried out with designed four nitrogen levels (0, 45, 180, 360 kg·hm-2, marked as N0, N45, N180 and N360, respectively). The dry matter at seedling stage and seed yield were determined. Then the N0 and N180 treatments were selected, the plant leaves were equally divided into 3 groups (upper, middle and lower) by leaf number from top to bottom. Some physiology and photosynthetic parameters (e.g., net photosynthetic rate (Pn max), nitrogen content (NA), chlorophyll content (Cc) and soluble protein nitrogen content (NS)) tested on leaves at different positions were measured to calculate nitrogen allocation in the photosynthetic apparatus (carboxylation, bioenergetics and light-harvesting components). 【Result】 Seed yield was increased significantly by nitrogen fertilization, compared with N0 treatment, N45, N180 and N360 were increased by 170%, 505.6% and 604.1%, respectively and the dry matter accumulation was consistent with the yield. Compared with N0 treatment, NA, Cc and Pn max were significantly increased in different leaf positions by nitrogen fertilization, but photosynthetic nitrogen use efficiency (PNUE) has significantly declined in the upper and middle leaves. For nitrogen allocation on the photosynthetic apparatus, the proportion of the carboxylation (PC), bioenergetics (PB) and light harvesting system (PL) in the upper and middle leaves of N180 treatment were lower than that of N0 treatment, but the nitrogen contents of those components were higher than that of N0 treatment and the increasing extent of the components were 20.6%, 11.8% and 28.8%, respectively. The ratio between soluble protein nitrogen content (NS) and non-soluble protein nitrogen content (Nnon-S) was not significantly influenced by whether nitrogen fertilization or not in the same position leaves, but the photosynthetic component partitioning in NS or Nnon-S was significantly influenced, which the ratio of nitrogen content of the carboxylation (NC) to NS was an average of 83.4% in all leaves in N0 treatment, while that of the N180 treatment was only 60.3%. Based on boundary line approach to quantify the influence of each component of the photosynthetic apparatus for PNUE, the results indicated that the influence degrees of PC and PB were 26.8% and 42.6%, significantly higher than that of PL. The influence of nitrogen nutrition on PNUE was dominated by PC and PB, which the average proportion reached 77.8%. PC was the main limiting factor of PNUE in upper leaves, which the influence degree reached 83.3%, while dominated by PB and PL in the lower leaves.【Conclusion】 Nitrogen fertilizer had a significant effect on increasing yield of winter rape and the optimum nitrogen application rate was 180 kg·hm-2. More nitrogen was allocated to photosynthetic apparatus by plant, and the photosynthetic nitrogen can be degraded earlier in the lower leaves under nitrogen deficiency. Suitable nitrogen level can maintain the distribution of the photosynthetic proteins within the types of their proteins. The effect of nitrogen nutrition on photosynthetic nitrogen use efficiency is dominated by allocation of nitrogen to the carboxylation and bioenergetics. The dominant effect by the distribution of the carboxylation was transformed to the dominant effect by the distribution of the light harvesting system and bioenergetics along with the decline of leaf position. Reference丨 Related Articles丨 Metrics

Guidance: Nitrogen Management with High Yield and High Efficiency for Oilseed Rape in China     LU Jian-wei Scientia Agricultura Sinica   2016,49(18 ):3504 -3505. DOI:10.3864/j.issn.0578-1752.2016.18.004 Abstract  （453） HTML （8） PDF（pc） （202KB）（675） Save Reference丨 Related Articles丨 Metrics

Effects of Nitrogen and Planting Density on Accumulation, Translocation and Utilization Efficiency of Carbon and Nitrogen in Transplanting Rapeseed with Blanket Seedling     Scientia Agricultura Sinica   2016,49(18 ):3522 -3531. DOI:10.3864/j.issn.0578-1752.2016.18.006 Abstract  （438） HTML （3） PDF（pc） （410KB）（536） Save 【Objective】 In order to discuss the relationship between carbon (C) and nitrogen (N) metabolism and yield in transplanting rapeseed with blanket seedling, the effects of different N application rates and planting densities on accumulation, translocation and utilization efficiency of carbon and nitrogen were studied. 【Method】 In this study, Ningza 1818 was planted by artificial transplanting with blanket seedling. The differences of C and N accumulation and translocation rates before and after flowering period, carbon utilization efficiency for grain production (CUEg) and nitrogen utilization efficiency for grain production (NUEg) under different years, nitrogen application rates and densities were studied. 【Result】The results showed that transplanting rapeseed with blanket seedling could obtain high yield (3 750 kg·hm-2) under suitable conditions. The yield increased significantly with increased densities under 0 and 225 kg·hm-2 N rates. There was no significant difference among 1 plant per spot, 2 plants per spot and 3 plants per spot with 125 000 spots/hm2 transplanting density under 300 kg·hm-2 N rate. The ability of C accumulation was significantly higher than that of N accumulation in rapeseed. The average C/N ratio before and after the early flowering period was 16.30 and 114.37, respectively. The CUEg and NUEg were declined with the increased N application, and the decline rates of NUEg were higher than those of CUEg. From the flowering period to the ripening period, the N translocation rate of the leaf was the highest, while that of the stem and the root ranked the second and the last, respectively. The N translocation rate of the leaf, stem and root from the flowering period to the ripening period ranged from 73.90% to 78.56%, 38.96% to 67.08% and 24.45% to 37.06% under different treatments. The differences of the N translocation rates of the leaf were slight, whereas those of the stem and root increased with increased N rates. From the flowering period to the ripening period, the C translocation rates of the leaf were positive values, which ranged from 23.16% to 29.08%. It increased generally as the N rates increased, and the differences resulted from N treatments were slight. From the flowering period to the ripening period, the root and the stem still accumulated C, and the C translocation rates of the root and the stem were negative values.【Conclusion】In the areas with the late harvest date of former crops, mechanical transplanting technology with blanket seedling could improve the production capacity of rapeseed. The ability of N metabolism before flowering was higher than that of after-flowering period while the ability of C metabolism had an opposite trend. N supply at early stage was conducive to form nutrition framework, which promoted the accumulation of C and yield formation from the flowering period to the ripening period. Reference丨 Related Articles丨 Metrics

Differences in Carbon Accumulation and Transport in Brassica napus with Different Nitrogen Use Efficiency and Its Effects on Oil Formation     ZHANG Xiao-long, ZHANG Zhen-hua, SONG Hai-xing, YU Jia-ling, GUAN Chun-yun Scientia Agricultura Sinica   2016,49(18 ):3542 -3550. DOI:10.3864/j.issn.0578-1752.2016.18.008 Abstract  （436） HTML （4） PDF（pc） （387KB）（377） Save 【Objective】The differences in carbon (C) accumulation and transport in Brassica napus with different nitrogen use efficiencies (NUE), were studied in order to supply a theoretical basis for elucidating the mechanism of high NUE genotypes in coordinating the contradiction between C and N metabolism and promoting oil formation.【Method】A soil culture experiment was conducted to study the differences of C accumulation and distribution in different organs of B. napus with different NUE at different growth stages (stem elongation stage, flowering stage, silique stage and harvest stage) under normal- and limited-N conditions, and using 13C isotope labeling to determine the C redistribution proportion and amount from vegetative organs to reproductive organs, analyze the contribution of C accumulation and transport to grain yield and oil accumulation.【Result】No significant differences in grain oil content between high- and low-NUE genotypes under the normal and limited-N application levels were observed, but the oil yield of high-NUE genotype was significantly higher than that of low-NUE genotype. Compared with limited-N, oil content was slightly decreased, but oil production was increased significantly under normal-N. There was no differences in C accumulation amount between high- and low-NUE genotypes, while the differences in C accumulation amount at different N application levels was significant, C accumulation amount of normal –N was significantly higher than that of limited-N. C allocation proportion in plant organs between high- and low-NUE genotypes was different, C allocation proportion in roots and leaves of high-NUE genotype was higher than that of low-NUE genotype at stem elongation stage and flowering stage, and C allocation proportion in silique and grain of high-NUE genotype was higher than that of low-NUE genotype at silique stage and harvest stage. While, C allocation proportion in stem of high-NUE genotype was lower than that of low-NUE genotype at the whole growth stage, and C allocation proportion in stem and root of high-NUE genotype was lower than that of low-NUE genotype at the whole growth stage. Compared with limited-N, C allocation proportion in leaves was increased at stem elongation stage and flowering stage under normal-N, while C allocation proportion in root was decreased. In addition, C allocation proportion in grain at harvest stage under normal-N was higher than what was observed in limited-N. As the development of plant growth stages, C distribution proportion and amount from vegetative organs to reproductive organs was gradually increased, the differences between genotypes were increased. Redistribution proportion and amount of C from vegetative organs to silique at silique stage and redistribution proportion and amount of C from vegetative organs to grain at harvest stage in high-NUE genotype was higher than that in low-NUE genotype, the significant different was occurred under normal-N. Redistribution proportion and amount of C in silique of high-NUE genotype was lower than that in low-NUE genotype under limited-N, and reversed results was observed under normal-N, the significant difference was occurred under limited-N. The 50% or more of C accumulation at stem elongation stage was left from vegetative organs, which was corresponding with redistribution proportion into reproductive organs, but C reduction proportion was significantly higher than C re-distribution proportion, which was because of the carbohydrate respiration consumption. 【Conclusion】 There was no significant difference in C accumulation between high- and low-NUE B. napus genotypes at different growth stages. However, higher proportion of C was redistributed from vegetative organs to reproductive organs in high-NUE genotype than that in low-NUE genotype at later growth stages. This is one of the important mechanisms for high-NUE genotype possesses with higher C source to relieve the contradictions between C and N, and promote oil formation during the process of grain formation. Reference丨 Related Articles丨 Metrics