不同降雨状况下渭北旱地春玉米临界氮稀释曲线与氮素营养诊断

过量施氮、降雨变率大和水氮耦合差是渭北旱地春玉米生产中氮肥高效利用的主要难题。构建渭北旱地不同降雨状况下春玉米临界氮稀释曲线,分析采用氮营养指数NNI诊断和评价旱地玉米氮素营养状况的可行性,为实现旱地玉米因雨合理施氮提供理论依据。以郑单958和陕单8806为试验材料,设置5个施氮量处理, 2016—2017年5个施氮量处理分别为0、75、150、270和360 kg hm-2, 2018—2019年施氮量调整为0、90、180、270和360 kg hm–2,文中依次用N0、N1、N2、N3、N4表示。其中2016年和2018年降水状况表现为穗期多雨,花粒期干旱; 2017年和2019年降水状况表现为穗期干旱,花粒期多雨,利用4年田间定位施氮试验数据构建并验证2种降雨状况下旱地春玉米临界氮稀释曲线模型。结果表明:(1)增施氮肥显著提高了旱地春玉米地上部生物量和植株含氮量,不同施氮量处理间差异显著。2种降雨状况下春玉米临界氮浓度和地上部生物量均符合幂指数关系,但模型参数之间存在差异(a.穗期多雨:Nc=35.98DM–0.35;b.穗期干旱:Nc=35.04DM–0.23)。模型拟合的植株氮浓度和实际氮浓度线性相关,穗期多雨年RMSE和n–RMSE分别为1.03、5.75%,穗期干旱年分别为1.53、6.78%,模型均具有较好稳定性。(2)在试验施氮量范围内,不同生育时期NNI随氮肥用量增加而增大,不同降雨状况下最佳施氮量存在差异。渭北旱地玉米最适施氮方案为基施氮肥150～180kghm–2,穗期多雨年追施氮肥45～75kghm–2。(3)氮营养指数NNI与相对吸氮量(RNupt)、相对地上部生物量(RDW)和相对产量(RY)均极显著相关,穗期多雨年NNI为1.02时, RY获得最大值,为0.95;穗期干旱年NNI为1.08时, RY获得最大值,为0.92。本研究建立的旱地玉米临界氮稀释曲线和氮营养指数,能够精准预测2种降雨状况下旱地春玉米拔节期至完熟期的氮素营养状况,对玉米生育季氮诊断及指导精确施氮具有重要意义。     

河北省主推中筋小麦品种面条加工适应性研究

为了解河北省主推中筋小麦品种的面条加工适应性、筛选优质面条小麦品种,对河北省19个主推中筋小麦品种的籽粒、面粉品质性状及面条加工品质特性进行了系统检测与分析。结果表明,河北省中筋小麦品种大部分品质性状的遗传多样性较为丰富;适宜制作面条加工的小麦品种有16个,占河北主推中筋小麦品种的84.21%,其中适宜制作优质面条的小麦品种有6个;面条感官总分与中筋小麦面粉的湿面筋含量呈极显著正相关,与拉伸长度呈显著正相关,与弱化度呈显著负相关,与面条质构参数(TPA)的粘聚性和回复性均呈极显著正相关,与面条TPA的弹性、胶着性、咀嚼度和拉伸距离均呈显著正相关;面条TPA指标参数可间接反映面条的感官品质。     

灌水对强筋小麦籽粒产量及营养品质的影响

为明确水地强筋冬小麦高产、优质、高效的灌溉技术，试验设3个灌水时期8个灌溉处理［越冬期灌1水（W₁），拔节期灌1水（W₂），孕穗期灌1水（W₃），越冬期和拔节期灌2水（W₁₂），越冬期和孕穗期灌2水（W₁₃），拔节期和孕穗期灌2水（W₂₃），越冬期、拔节期和孕穗期灌3水（W₁₂3），全生育期不灌水处理（CK）］,于小麦成熟期测定籽粒产量、总蛋白及其组分含量和淀粉含量。结果表明，与不灌水的CK比较，所有灌水处理的籽粒产量、有效穗数、穗粒数、千粒重、蛋白质产量以及籽粒淀粉含量均显著增加，但籽粒的总蛋白及其组分含量均呈不同程度降低（W₁处理除外）。越冬期灌水对有效穗数、籽粒产量、总蛋白及其组分含量、淀粉含量的提升作用较大；拔节期灌水对穗粒数的提升作用较大，但对淀粉含量的提升作用较小，对总蛋白及其组分含量的降低作用较大；孕穗期灌水对千粒重的提升作用较大，对蛋白质产量的提升作用较小。随着灌水次数增加，小麦籽粒产量显著提高，淀粉含量先显著提高后基本不变，而籽粒总蛋白及其组分含量降低。W₁₂3处理籽粒产量最高，其次是W₁₃处理；W₁处理籽粒蛋白质及其组分含量最高，其次是W₁₂及W₁₃处理；W₂₃处理淀粉含量最高，其次是W₁₂或W₁₃处理。综合各项指标，最好的灌水组合是越冬期和孕穗期灌2水（W₁₃）。     

小麦骨干亲本‘鲁麦14’的育种价值分析

为更加科学地开展小麦理论研究和提高育种成效,对‘鲁麦14’的构思设计与创制思路、突出特点和以‘鲁麦14’为亲本选育出的品种进行了系统分析。从2001年到2018年,中国科学院、中国农科院、中国农业大学和山东、江苏、河北、安徽、河南、山西、陕西、新疆、贵州、天津9省1市的89家科研单位和育种企业,以‘鲁麦14’为亲本直接育成品种39个、间接育成品种92个,这些品种通过9省2市166次审（认）定和36次国家审定。‘鲁麦14’作为新一代骨干亲本,为全国的小麦生产和育种工作做出了突出贡献。     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.     

耕作方式及秸秆还田对土壤性质、微生物碳源代谢及小麦产量的影响

以小麦品种济麦22为试验材料,采用裂区试验设计,耕作方式为主区,分别设常规翻耕(C)、深松(S)、旋耕(R)处理,副区为秸秆还田量,分别设秸秆全还田(P)和秸秆不还田(A)处理,采用Biolog Eco技术测定土壤微生物碳源代谢功能,并分析土壤基本理化性质和作物产量。结果显示:深松与秸秆还田均有利于土壤含水量和有机碳含量的提高,0～15 cm土层分别提高了9.78%和24.00%,15～30 cm土层分别提高了7.08%和15.81%;深松提高了15～30 cm土层的pH值6.67%,秸秆还田提高了0～15 cm土层的pH值4.32%。深松和秸秆还田均有利于代谢多样性(丰富度指数、香浓多样性指数)、碳源代谢强度的提高,0～15 cm土层分别提高了26.84%、3.84%和38.02%,15～30 cm土层分别提高了11.87%、 3.63%和14.74%。主成分分析表明常规翻耕秸秆不还田和旋耕耕作秸秆不还田碳源代谢功能相近,15～30 cm层次内常规翻耕秸秆全还田碳源代谢功能和深松耕作秸秆全还田处理相近。深松和秸秆还田平均提高了小麦产量5.82%,微生物碳源代谢功能与小麦产量具有极显著的相关性。     

Ridge-furrow plastic mulching with a suitable planting density enhances rainwater productivity,grain yield and economic benefit of rainfed maize

Soil surface mulching and planting density regulation are widely used for effective utilization of limited rainwater resources and improvement of crop productivity in dryland farming.However,the combined effects of mulching type and planting density on maize growth and yield have been seldom studied,especially in different hydrological years.A field experiment was conducted to evaluate the effects of mulching type and planting density on the soil temperature,growth,grain yield(GY),water use efficiency(WUE)and economic benefit of rainfed maize in the drylands of northern China during 2015-2017.Precipitation fluctuated over the three years.There were four mulching types(NM,flat cultivation with non-mulching;SM,flat cultivation with straw mulching;RP,plastic-mulched ridge plus bare furrow;RPFS,plastic-mulched ridge plus straw-mulched furrow)and three planting densities(LD,low planting density,45.0×10^3 plants/hm^2;MD,medium planting density,67.5×10^3 plants/hm^2;HD,high planting density,90.0×10^3 plants/hm^2).Results showed that soil temperature was higher with RP and lower with SM compared with NM,but no significant difference was found between RPFS and NM.More soil water was retained by soil mulching at the early growth stage,but it significantly varied at the middle and late growth stages.Maize growth was significantly improved by soil mulching.With increasing planting density,stem diameter,net photosynthetic rate and chlorophyll content tended to decline,whereas a single-peak trend in biomass yield was observed.Mulching type and planting density did not have significant effect on evapotranspiration(ET),but GY and WUE were significantly affected.There were significant interacting effects of mulching type and planting density on biomass yield,GY,ET and WUE.Compared with NM,RPFS,RP and SM increased GY by 57.5%,50.8%and 18.9%,and increased WUE by 66.6%,54.3%and 18.1%,respectively.At MD,GY increased by 41.4%and 25.2%,and WUE increased by 38.6%and 22.4%compared with those of at LD and HD.The highest maize GY(7023.2 kg/hm^2)was observed under MD+RPFS,but the value(6699.1 kg/hm^2)was insignificant under MD+RP.Similar trends were observed for WUE under MD+RP and MD+RPFS,but no significant difference was observed between these two combinations.In terms of economic benefit,net income under MD+RP was the highest with a 9.8%increase compared with that of under MD+RPFS.Therefore,we concluded that RP cultivation pattern with a suitable planting density(67.5×10^3 plants/hm^2)is promising for rainwater resources utilization and maize production in the drylands of northern China.     

Quantitative trait loci analysis for root traits in synthetic hexaploid wheat under drought stress conditions

Synthetic hexaploid wheat(SHW), possesses numerous genes for drought that can help breeding for drought-tolerant wheat varieties. We evaluated 10 root traits at seedling stage in 111 F9 recombinant inbred lines derived from a F2 population of a SHW line(SHW-L1) and a common wheat line, under normal(NC) and polyethylene glycol-simulated drought stress conditions(DC). We mapped quantitative trait loci(QTLs) for root traits using an enriched high-density genetic map containing 120 370 single nucleotide polymorphisms(SNPs), 733 diversity arrays technology markers(DArT) and 119 simple sequence repeats(SSRs). With four replicates per treatment, we identified 19 QTLs for root traits under NC and DC, and 12 of them could be consistently detected with three or four replicates. Two novel QTLs for root fresh weight and root diameter under NC explained 9 and 15.7% of the phenotypic variation respectively, and six novel QTLs for root fresh weight, the ratio of root water loss, total root surface area, number of root tips, and number of root forks under DC explained 8.5–14% of the phenotypic variation. Here seven of eight novel QTLs could be consistently detected with more than three replicates. Results provide essential information for fine-mapping QTLs related to drought tolerance that will facilitate breeding drought-tolerant wheat cultivars.     

Genome-wide association analysis for stripe rust resistance in spring wheat(Triticum aestivum L.) germplasm

Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance(APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D' measure, linkage disequilibrium(LD) exhibited between loci distant up to 45 c M. Marker-trait associations(MTAs) were determined using mixed linear model(MLM). Total 31 quantitative trait loci(QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2 AL and QYr.uaf.3 BS(PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.