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.

Nutrient deficiency limits population development,yield formation,and nutrient uptake of direct sown winter oilseed rape

Direct-sowing establishment method has great significance in improving winter oilseed rape（Brassica napus L.） production and guaranteeing edible oil security in China. However, nutrient responses on direct sown winter oilseed rape（DOR） performance and population development dynamic are still not well understood. Therefore, five on-farm experiments were conducted in the reaches of the Yangtze River（RYR） to determine the effects of nitrogen（N）, phosphorus（P）, and potassium（K） deficiencies on population density, dry matter production, nutrient uptake, seed yield, and yield components of DOR plants. Four fertilization treatments included the balanced NPK application treatment（NPK, 180 kg N, 39.3 kg P, 100 kg K, and 1.8 kg borax ha–1） and three nutrient deficiency treatments based on the NPK treatment, i.e., –N, –P, and –K. The results indicated that DOR population density declined gradually throughout the growing season, especially at over-wintering and pod-development stages. Nutrient deficiency decreased nutrient concentration in DOR plants, limited dry matter production and nutrient uptake, and thereby exacerbated density reduction during plants growth. The poor individual growth and reduced population density together decreased seed yield in the nutrient deficiency treatment. Averaged across all the experiments, seed yield reduced 61% by N deficiency, 38.3% by P deficiency, and 14.4% by K deficiency. The negative effects of nutrient deficiency on DOR performances followed the order of –N–P–K, and the effects were various among different nutrient deficiencies. Although N deficiency improved DOR emergence, but it seriously limited dry matter production and nutrient uptake, which in turn led to substantial plants death and therefore resulted in a very low harvested density. The P deficiency significantly reduced initial density, limited plants growth, and exacerbated density reduction. The K deficiency mainly decreased individual growth and yield, but did not affect density dynamic. Our results highlighted the importance of balanced NPK application in DOR production, suggesting that management strategy of these nutrients should be comprehensively considered with an aim to build an appropriate population structure with balanced plant density and individual growth.

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.

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.

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.

Analysis of yield and quality characteristics of winter oilseed rape in China from 2001 to 2015: towards future breeding goals

The exciting outcomes of national regional trials have led to production and industrialization of China oilseed rape to a larger extent. To understand current trends of yield and quality traits of new varieties, data of national winter oilseed rape trials from 2001 to 2015 in 4 districts （upper, middle, lower Yangtze River and Huang-Huai River） was comprehensively analyzed. Results showed that average yield of new varieties of winter oilseed rape increased during the study period. In 2013, average yield of each district reached its highest level. Number of pod per plant reached its peak in 2011 and then declined rapidly in the next 4 years. Average number of seeds per pod did not signif-cantly changed in any districts. Moreover, 1,000 seeds weight increased most obviously in Huang-Huai River district. After 2007, new oilseed rape varieties encountered the dou-ble-low quality （i.e., low erucic acid and low glucosinolate）. In addition, oil content of new oilseed rape varieties increased over 15 years period and average oil content of all tested varieties during 2006-2015 was 42.96%, which was 2.38% higher than in 2005. Future breeding goals should be set to further improve yield, oil content, oil quality （such as high oleic acid and low saturated fatty acids）, achieve full mechanization of oilseed rape pro-duction process and develop ideotypes.

Brassinosteroids promote seed development and physiological maturity of oilseed rape (Brassica napus L.)

Long developmental stage and late harvest time of winter rapeseed (Brassica napus L.) have great negative effects on rice planting of rice-rapeseed farming system in China. Early maturity improvement of rapeseed is necessary. ‘Zhongshuang 11’, an elite winter rapeseed cultivar, was used in consecutive field experiments during 2010-2012. At initial flowering stage, plants were consecutively sprayed with 0.1 mg/L 2-4-Epibrassinolide(BR) for 3 d. Two hundred sampling pods from different plants were randomly collected to measure seed related indexes with a 4 d interval from 7 to 47 d after peak anthesis (DAPA).Seed color turned light brown at 31 or 35 DAPA after BR treatment, seed dry weight (DWT)was increased while seed moisture content (SMC) was decreased during seed development.DWT almost reached the maximum value when SMC was 33.20% at 31 DAPA in 2010-2011 and 35.29% at 35 DAPA in 2011-2012 growing season after BR treatment. Similarly,the maximum values of standard germination test (SGT), accelerated aging test (AAT)and cold test (CT) were observed at 31 or 35 DAPA after BR treatment respectively. The high yield and seed oil content appeared at 31 or 35 DAPA accompanied with rapid decrease in total non-structural carbohydrate (TNC) in stems and leaves. Our study indicated that BR application advanced maturity of winter rapeseed by 4 to 8 days.

Influence of Nostoc entophytum and Tetracystis sp. on Winter Survival of Rapeseed

Bioassay results proved that several microalgae strains of the Mosonmagyaróvár Algal Culture Collection (MACC) enhanced plant growth, due to their hormone content and other secondary metabolites. The aim of the current research was to improve autumn growth and winter survival of rapeseed (Brassica napus L.) by treatment with two microalgae strains selected by bioassay results. Experimental plots were set up in Mosonmagyaróvár in 2010 and 2013. Winter rapeseed hybrid (B. napus L. cv. Orlando) plants were treated in 4-6 leaves stage with 0.3 g/L and 1 g/L suspensions of MACC-612 Nostoc entophytum Bornet & Flahault and MACC-430 Tetracystis sp. in middle of October. After the treatments, the following parameters were recorded: chlorophyll-a and b, carotenoid, dry matter content of leaves, average amount of autumn foliage, diameter of root collar, length of shoot tips, fresh and dry weight of root, and number of plants in autumn and spring. Both microalgae treatments significantly increased pigment concentration and dry matter content of leaves, number of fully grown leaves (13%-46%) and dry root weight (16%-36%). Treatments with 0.3 g/L and 1 g/L MACC-612 suspensions increased the length of shoot apices by 14%-18% and 25%-35%, respectively. Number of overwintered control plants decreased significantly in both years (31%), but there was no decrease in parcels treated with 1 g/L of MACC-612 and MACC-430. Microalgae treatments could increase plant growth and survival, which contributed to the significant increase of thousand seed weight (18%-25%) and total yield (by 10%-24%).

我国冬油菜的气候灾损变化及其对ENSO响应

构建冬油菜气候灾损与ENSO事件的可能关系有利于应对气候变化对油料供给的影响。基于12个主产省市1980—2019年的冬油菜单产序列,通过H-P滤波与时序全局主成分分析识别了气候灾损的年代差异。此外,梳理了主要气象灾害以及不同ENSO年型对灾损的影响,进而探讨了9种ENSO指数的预判作用。主要结果如下:①冬油菜种植效率的区域均衡性呈现出显著的上升趋势;②多数省市的气候灾损在1980s和1990s有着更高强度;③冻灾和雹灾对冬油菜种植有着更不利的影响;④ENSO强冷事件支配年份的气候灾损明显更高;⑤极端东部热带太平洋海表温度等因子驱动的分类模型对灾损年景有着较好的预判效果。

长江中游南部油菜产区低产原因及育种对策

为明确长江中游南部地区影响油菜产量的关键气象因子,提高油菜育种效率,本文以长江中游2018-2020三年试验点的气象数据及参加国家冬油菜品种试验的106个油菜品种为基础数据进行分析。结果表明:相同油菜品种栽培条件下,南部地区的单产为2307.15 kg/hm^(2),比北部偏低25.28%,其中千粒重、每角粒数、有效分枝数和菌核病病情指数差异最大,分别降低16.09%、4.43%、9.19%和27.84%。通径分析表明南部地区油菜品种产量构成与北部显著不同,南部地区对小区产量直接作用大小依次为有效分枝数(0.2538)>千粒重(0.2887)>每角粒数(0.1469)>菌核病病情指数(-0.3981),北部地区对小区产量直接作用大小依次为全生育期(0.5798)>单株有效角果数(0.2128)>每角粒数(0.1624)>千粒重(-0.1630)。气象因子与产量回归分析表明,南部地区油菜产量与11月平均温度显著负相关,1月和3月昼夜温差显著正相关,11月和12月最低温显著负相关,2月和4月最低温极显著正相关,2月和4月降雨量显著负相关。从整个生育期看,长江中游南部地区主要影响油菜产量气象因子为昼夜温差、最低温度和降雨量。育种策略中,南部地区除了选育耐高温性和耐渍涝的油菜品种外,还应加强对千粒重、有效分枝数、每角粒数的选择,为进一步提高南部地区油菜单产提供理论依据。

Effects of harvesting method and date on yield loss and seed quality of rapeseed

China is one of the major rapeseed production countries in the world,but harvesting mechanization was still backward,and high harvest loss was a key inhibiting factor for rapeseed production.To obtain optimum harvesting date for winter rape in the Yangtze River Valley of China,artificial simulated combine harvesting and artificial two-stage harvesting were adopted to find correlations between harvesting date,rape variety,seed oil content,protein content,grain moisture rate,rapeseed straw moisture content,rapeseed unthreshing rate,grain drop loss rate,thousand seeds weight(TSW),and harvesting economic coefficient(HEC).Analysis of variance showed that rapeseed oil content,protein content and TSW were correlated with rape variety;HEC was correlated with harvesting method and rape variety.Rape variety was the dominant factor of rapeseed oil content,protein content,TSW and HEC.Grain moisture rate,un-threshing rate,grain drop loss rate and straw moisture content were correlated with harvesting method and date.Harvesting date was the dominant factor of rapeseed moisture rate,un-threshing rate,grain drop loss rate and straw moisture rate.Single factor tests further proved that harvesting date had less impact on rapeseed oil content,protein content,TSW and HEC.It showed little correlation with rapeseed quality except grain moisture rate.The optimum harvesting date could be known by change in straw moisture content.The combined harvesting should be carried out during the grain moisture content of 15%-20%with TSW stabilized in the highest level.The twostage harvesting cutting should be carried out at the grain moisture content of 35%-40%.This research offered a reference to harvesting method and date for rape cultivated in the Yangtze River Valley.

氮肥用量对冬油菜籽粒产量和品质的影响

为探明不同氮肥用量对冬油菜籽粒产量和品质的影响,于2019/2020以及2020/2021年在湖北省武穴市开展田间试验,试验设置0、90、180、270、360 kg N hm^(-2)5个氮肥施用水平。在成熟期测定油菜籽产量、氮含量和油菜籽品质指标。结果表明,施氮显著提高冬油菜籽粒产量及氮含量,与不施氮相比,氮肥施用后平均增产1548 kg hm^(-2),平均增产率达32.9%,在施氮量为0~270 kg N hm^(-2)范围内,油菜籽产量随氮肥施用量显著增加,继续增施氮肥,油菜籽产量无明显变化或有下降趋势,施氮主要通过提高单株角果数来提高油菜籽粒产量。施氮显著增加了籽粒蛋白质含量,当施氮量达270 kg N hm^(-2)时籽粒氮含量和蛋白质含量最高。施氮显著降低籽粒含油量,氮肥用量每增加100 kg N hm^(-2),籽粒含油量下降1.6个百分点。随着氮肥用量的增加,籽粒硫甙、油酸、亚麻酸、芥酸以及饱和脂肪酸(棕榈酸和硬脂酸)呈升高趋势,亚油酸呈降低趋势,油菜籽粒品质整体呈降低趋势。综上所述,以追求高品质食用油为目标,同时兼顾油菜籽粒产量,氮肥适宜用量约为180kgNhm^(-2);以追求油菜籽粒产量并考虑油菜饼粕作饲料为目标时,氮肥适宜用量约为270 kg N hm^(-2)。

利用相关矩阵法优化光谱指数的冬油菜氮素营养诊断

近年来高光谱技术由于无损和高效等优点成为了现代精准农业发展的必要手段方法。为实现冬油菜无损、快速的氮素盈亏诊断,该研究以连续两年(2022—2023年)不同覆盖及施氮处理下冬油菜蕾薹期采集的90份植物样品(地上部生物量和植株氮浓度)和高光谱实测数据为数据源,根据原始光谱和一阶微分(first-order differential,FD)光谱与氮营养指数(nitrogen nutrition index,NNI)的相关系数计算了8种(共16个)典型的光谱指数,随后利用相关矩阵法提取最佳光谱组合,并根据与NNI相关系数的计算结果筛选最优光谱指数,最后将最优光谱指数分为3组模型输入变量,分别采用支持向量机(support vector machine,SVM)、随机森林(random forest,RF)、极限学习机(extreme learning machine,ELM)和反向神经网络(back propagation neural network,BPNN)构建冬油菜蕾薹期NNI估算模型。结果表明一阶微分光谱指数与NNI的相关系数均大于原始光谱指数,3个组合选择的光谱指数与NNI的相关系数均较高且波长组合位置均在红边(670~760 nm)内,与NNI相关系数最高的光谱指数为FDSAVI,为0.674,波长组合位于712和678 nm;冬油菜NNI估算模型的最优输入变量与最优建模方法相结合建立的模型为组合2(输入变量为一阶微分光谱指数)与RF模型相结合,其中最优模型验证集的决定系数为0.823,均方根误差为0.079,平均相对误差为7.513%,表明模型精度较高,预测结果将为遥感技术在作物生产中植物氮素营养监测和诊断的潜在应用提供技术依据。

冬油菜主产区近40年土壤基本理化性质变化特征

【目的】探究近40年长江流域冬油菜主产区土壤基本理化性质的变化,明确冬油菜种植区耕地土壤综合肥力变化特征,以期为长江流域中低产田保育和土壤肥力改良提供科学依据。【方法】通过收集整理近40年国内外公开发表的文献及硕士、博士论文数据,分析长江流域冬油菜种植区土壤基础性质的时序变化特征,评估土壤综合肥力变化及其与土壤基础理化性质的相关性。【结果】1981—1990年长江流域冬油菜主产区耕层土壤有机质、全氮、有效磷、速效钾、pH均值分别为18.54 g·kg^(-1)、1.16 g·kg^(-1)、8.60 mg·kg^(-1)、42.90 mg·kg^(-1)和6.26,2016—2020年这些指标的均值分别为25.60 g·kg^(-1)、1.41 g·kg^(-1)、18.66 mg·kg^(-1)、108.98 mg·kg^(-1)和6.31,40年来长江流域冬油菜区土壤基础理化性质得到很大程度的改善。其中土壤有机质、全氮年均增幅分别为1.2%和0.7%,土壤有效磷、速效钾含量年均增幅达3.0%和4.0%,土壤pH则在近40年内保持稳定(不同时段平均值范围6.21—6.45)。基于改进的内梅罗指数法评估表明,IFI(土壤综合肥力指数)值逐年上升,其中2001—2020年IFI均值较1981—2000年显著提高14.8%—30.4%。土壤有机质、pH、全氮、有效磷、速效钾与IFI呈极显著正相关性,通径分析表明土壤速效钾是影响冬油菜区IFI最大的指标,其次是土壤全氮和有效磷。【结论】近40年来长江流域冬油菜主产区的土壤基础理化性质和综合肥力显著提高。发展油菜种植有利于提高长江流域农田土壤生产力,是长江流域中低产田地力提升的有效途径。

天水地区冬油菜化肥减量增效试验结果初报

通过优化天水地区冬油菜施肥方案,在不降低产量和产出效益的前提下,明确减轻化肥施用对环境的污染的最佳施肥量。以天油15号为指示品种,在武山县设常规施肥、常规施肥减量15%、减量25%、减量30%、减量50%+有机肥共5个处理,观察化肥减量对冬油菜生育期、主要农艺性状、产量及效益的影响。结果表明,化肥减量15%~50%对天油15号生育期基本不影响,但其主要农艺性状表现均以化肥减量25%处理最好,减量30%次之;减量25%和30%处理均较常规施肥增产,但增产不显著;常规施肥减量30%的产投比最高,减量25%次之。综上所述,相比常规施肥,化肥减量25%~30%既能保证冬油菜高产,又能减少投入成本,获得较好的收益。

甘南高寒区白菜型冬油菜适宜密度研究

在甘南开展白菜型冬油菜适宜种植密度试验,为高寒区示范推广冬油菜提供技术支持。设45万、60万、75万、90万、105万株/hm2共5个种植密度,研究种植密度对高寒区冬油菜越冬率、生育期、产量及经济性状的影响。结果表明,5个密度处理的冬油菜均能正常越冬,越冬率随种植密度的增加而降低。密度60万株/hm2的处理表现出良好的群体效应,越冬率为89.7%,性状优良,折合产量最高,为1971 kg/hm2。

长江流域直播冬油菜氮磷钾硼肥施用效果

冬油菜直播种植的推广应用对提高我国油菜籽总产量和保障食用油安全有重要意义。2009—2010年度在长江流域6个冬油菜主产省布置36个大田试验,研究当前生产条件下我国直播冬油菜的氮磷钾硼肥施用效果和肥料利用率,比较农民习惯施肥与推荐施肥的差异,并与移栽油菜施肥效果进行对比,以探讨直播冬油菜的施肥管理措施。结果显示,在推荐施肥量和施肥方法条件下,氮磷钾硼肥配合施用(NPKB)处理直播冬油菜的油菜籽产量和产值平均分别为2001 kg hm–2和8205元hm–2,显著高于农民习惯施肥(FFP)处理,施用效果为N>P>B>K。NPKB配合施用显著促进直播冬油菜的养分吸收,N、P、K累积量分别为104.2、20.4和160.2 kg hm–2。NPKB配施条件下,直播冬油菜的氮、磷、钾肥表观利用率平均分别为35.8%、22.3%和45.9%,明显高于农民习惯施肥的20.8%、7.2%和28.0%。说明合理施肥对直播冬油菜生产有重要作用,现阶段应积极推行氮磷钾硼肥配施技术,并根据生长发育特点和养分吸收规律调整肥料的施用时期和比例。

施肥深度对冬油菜产量、根系分布和养分吸收的影响

为了确定冬油菜较优的施肥深度,通过2 a桶栽试验,设置5个施肥深度：地表施肥和地下5、10、15、20 cm施肥,分别记为CK、D_5、D_（10）、D_（15）和D_（20）,并另设不施肥处理（F0）,研究不同施肥深度处理对冬油菜地上部干物质量、不同土层的主根干质量和侧根干质量、侧根长、侧根体积和侧根表面积及冬油菜地上部植株的养分吸收情况和籽粒产量的影响。结果表明,D_（15）处理在冬油菜花期能显著增加5~20 cm和20 cm以下土层的主根干质量以及主根总干质量,而0~5 cm土层的主根干质量与CK和D_5处理相比降低幅度不大;D_（15）处理在冬油菜苗期和花期10~20 cm土层的侧根干质量、侧根长、侧根体积和侧根表面积均为最大,且均显著大于CK和D_5处理。在冬油菜花期和收获时D_（15）处理的地上部干物质量及地上部植株的氮、磷、钾吸收量最大,且D_（15）处理的油菜籽粒产量及籽粒中的氮、磷、钾吸收量最大,并显著大于CK、D_5和D_（10）处理;收获时,2 a D_（15）处理地上部植株中的氮、磷、钾的平均吸收量与CK相比分别增加48.07%、52.18%和62.96%,与D_5相比分别增加25.75%、30.19%和33.41%,与D_（10）相比分别增加10.59%、15.33%和17.06%。D_（15）处理2 a的平均产量与CK、D_5和D_（10）处理相比,分别提高85.10%、45.47%和31.26%;与D_（20）处理相比提高了3.89%。综合考虑不同施肥处理冬油菜的根系分布、养分吸收量和籽粒产量,地表下15 cm（D_（15）处理）为冬油菜较优的施肥深度。