Dynamics of Essential Metal Elements Contents in Winter Oilseed Rape during Cold Acclimation

[Objective]The paper was to investigate the dynamics of essential metal elements（Ca,Mg,Fe,Mn,Zn and Cu）contents in winter oilseed rape（Brassica napus L.）during cold acclimation,and to reveal the effects and mechanisms of essential elements in cold resistance of oilseed rape.[Method]Three varieties with different cold resistance including Zhongshuang No.11（ZS,freezing sensitive variety）,Ganyouza No.1（GY）and Jinyuyou No.1（JYY,freezing tolerant varieties）were used in the study,and the changes of necessary metal elements in these oilseed rapes during cold acclimation were studied.[Result]The concentration of metal elements in oilseed rape had significant changes during cold acclimation,and the difference between varieties was significant.In plant roots,the concentrations of Ca,Mg,Fe,Mn,Zn and Cu were significantly increased,this might because that low temperature made the transpiration decreased,thus blocking the upward transport of elements.In plant shoots,the concentrations of Ca,Mg and Zn were significantly decreased,while the concentrations of Fe and Mn were significantly increased;the change extent of various elements in ZS variety was the largest.[Conclusion]Maintaining the stability of Ca,Mg and Zn concentrations and increasing Fe,Mn and Cu concentrations in plant shoots might be benefit for increasing the cold tolerance of winter oilseed rape.

Effects of Nitrogen Fertilization on the Growth and N Uptake of Late-sowing Winter Oilseed Rape (Brassica napus L.)

[Objective] The aim of this work was to analyze the N fertilization on the vegetative growth and N uptake of different winter rapeseed varieties at wintering stage. [Method] In two consecutive years （2009-2011）, two winter rapeseed varieties （B. napus L.）, an early maturity variety Zhongyou 116 （ZY116） and a middle-late application maturity variety Zhongyouza 12 （ZYZ12） were employed. Field experiments with different N levels （0, 90, 180, 270, 360 kg N/hm 2 ） were designed. At the wintering stage, the dry matter weight, the nitrogen content and concentration of plants, leaf nitrate reductase activity （NRA） and seed yields were investigated. [Result] The shoot dry matter of ZY116 increased rapidly when N rate ranged from 0 to 180 kg/hm 2 , and it raised slightly when N rate ranged from 180 to 360 kg/hm 2 . The shoot dry matter of ZYZ12 were changed in a single peak curve; the peak of shoot dry matter appeared at 270 kg N/hm 2 . The N concentration and N content in shoot and root increased rapidly when the N rate changed from 90 to 180 kg/hm 2 . Moreover, the N concentration and N content root of in ZYZ12 were much higher than that of ZY116. Present study revealed that the changed trend of leaf nitrate reductase activities （NRA） were significantly increased at the N rate of 180 kg/hm 2 in ZY116 and ZYZ12 compared with the N rate of 90 kg/hm 2 in two years. [Conclusion] Optimal nitrogen application significantly increased the dry weights and N uptake at wintering stage as well as increasing the yield of winter oilseed rape.

Mechanical Harvesting Effects on Seed Yield Loss,Quality Traits and Profitability of Winter Oilseed Rape (Brassica napus L.)

China is one of the most important rapeseed producing countries in the world. Effective mechanical harvesting time for decreasing harvesting loss of winter oilseed rape has been becoming a critical factor. An elite cultivar Zhongshuang 11 （Brassica napus L.） was employed in two rounds of field experiments from 2009 to 2011. Seeds were sown with machine, three combine harvesting times namely combine harvesting A, B, and C （CHA, CHB, and CHC） were designed and manual harvesting （MH） as control was performed at maturity. The harvesting treatments were determined according to color of pod and seed in the field. Seed yield loss and quality in different treatments were evaluated. Results showed that both seed yields and harvesting losses in 2009-2010 were higher than that in 2010-2011, whereas seed oil contents in 2010-2011 were higher than that in 2009-2010. The highest yield appeared in CHB, which was significantly higher than that in MH. Furthermore, harvesting loss in CHB were 50% that in MH. Seed oil content and chlorophyll exhibited no obvious difference between CHB and MH. Economic profit analysis demonstrated that mechanical sowing/combine harvesting （MS/CH） showed an input/output ratio of 1：1.6, and it was 1：1.2 in mechanical sowing/manual harvesting （MS/MH）. Labor-cost accounted for more than 70% of the total cost in MS/MH, which led to low profitability to a great extent. Our results suggested that CHB was the optimum harvesting time for winter oilseed rape along the Yangtze River.

Utilizing comprehensive decision analysis methods to determine an optimal planting pattern and nitrogen application for winter oilseed rape

Oilseed rape is one of the most important oil crops globally.Attaining the appropriate cultivation method(planting pattern and nitrogen level)is necessary to achieve high yield,quality and resource utilization efficiency.However,the optimal method for oilseed rape varies across countries and regions.The objective of the present study was to determine an appropriate cultivation method,including planting pattern and nitrogen application,for winter oilseed rape in northwestern China.Two planting patterns:ridge film mulching and furrow planting(RFMF)and flat planting(FP),and six nitrogen(N)amounts:0(N0),60(N60),120(N120),180(N180),240(N240),and 300(N300)kg N ha–1 were applied across three growing seasons(2014–2017).Three comprehensive decision analysis methods:principal component analysis,grey correlation degree analysis and the combined entropy weight and dynamic technique for order preference by similarity to ideal solution method were used to evaluate the growth and physiological indicators,nutrient uptake,yield,quality,evapotranspiration,and water use efficiency of winter oilseed rape.Planting pattern,nitrogen amount and their interaction significantly affected the indicators aforementioned.The RFMF pattern significantly increased all indicators over the FP pattern.Application of N also markedly increased all the indicators except for seed oil content,but the yield,oil production and water use efficiency were decreased when N fertilizer exceeded 180 kg N ha–1 under FP and 240 kg N ha–1 under RFFM.The evaluation results of the three comprehensive decision analysis methods indicated that RFMF planting pattern with 240 kg N ha–1 is an appropriate cultivation method for winter oilseed rape in northwestern China.These findings are of vital significance to maximize yield,optimize quality and improve resource use efficiencies of winter oilseed rape.

Ridge-furrow rainwater harvesting with supplemental irrigation to improve seed yield and water use efficiency of winter oilseed rape(Brassica napus L.)

Ridge-furrow rainwater harvesting （RFRH） planting pattern can lessen the effect of water deficits throughout all crop growth stages, but water shortage would remain unavoidable during some stages of crop growth in arid and semiarid areas. Supplemental irrigation would still be needed to achieve a higher production. Field experiments were conducted for two growing seasons （2012-2013 and 2013-2014）to determine an appropriate amount of supplemental irrigation to be applied to winter oilseed rape at the stem-elongation stage with RFRH planting pattern. Four treatments, including supplemental irrigation amount of 0 （I1）, 60 mm （I2） and 120 mm （I3） with RFRH planting pattern and a control （CK） irrigated with 120 mm with flat planting pattern, were set up to evaluate the effects of supplemental irrigation on aboveground dry matter （ADM）, nitrogen nutrition index （NNI）, radiation use efficiency （RUE）, water use efficiency （WUE）, and seed yield and oil content of the oilseed rape. Results showed that supplemental irrigation improved NNI, RUE, seed yield and oil content, and WUE. However, the NNI, RUE, seed yield and oil content, and WUE did not increase significantly or even showed a downward trend with excessive irrigation. Seed yield was the highest in 13 for both growing seasons. Seed yield and WUE in 13 averaged 3235 kg ha^-1 and 8.85 kg ha^-1 mm-1, respectively. The highest WUE was occurred in 12 for both growing seasons. Seed yield and WUE in 12 averaged 3089 kg ha^-1 and 9.63 kg ha^-1 mm^-1, respectively. Compared to 13, 12 used 60 mm less irrigation amount, had an 8.9% higher WUE, but only 4.5 and 0.4% lower seed yield and oil content, respectively. 12 saved water without substantially sacrificing yield or oil content, so it is recommended as an appropriate cultivation and irrigation schedule for winter oilseed rape at the stem-elongation stage.

Responses of Seed Yield and Economic Benefit of Winter Oilseed Rape(Brassica napus L.) to Different NPK Ratio and Dose

Field experiments were conducted during 2008-2010 to investigate the ef- fects of NPK fertilization on seed yield and economic benefit of a new hybrid cultivar of winter oilseed rape （Brassica napus L.） - Xiangzayou763, and to determine the optimum NPK ratio and dose in Hunan, China. The results showed that NPK ratio （1：0.50：0.50） with 180 kg/hm2 N, 90 kg/hm2 P2O5 and 90 kg/hm2 K20 was the optimum combination for the highest seed yield （2 231.13 kg/hm2） and economic benefit （9 816.97 Yuan/hm2）, of which 1 641.23 Yuan/hm2 being set for fertilizer in- vestment （VCR=4.11）. Besides, the effects of N, P and K fertilizers on seed yield and oil production of winter oilseed rape were not identical. N had the greatest ef- fect on plant growth of winter oilseed rape, followed by P and K. Total leaf number, green leaf number, leaf length and width, rhizome diameter, branch number, dry weight per plant and other agronomic characters in high N treatments were higher than those in low N treatments. By correlation and path analysis of yield components, the contribution rate to seed yield was found： effective silique number per plant〉seed number per silique〉l 000-seed weight.