Tillage and straw mulching impacts on grain yield and water use efficiency of spring maize in Northern Huang–Huai–Hai Valley

A two-year field experiment(2012–2013) was conducted to investigate the effects of two tillage methods and five maize straw mulching patterns on the yield, water consumption,and water use efficiency(WUE) of spring maize(Zea mays L.) in the northern Huang–Huai–Hai valley of China. Compared to rotary tillage, subsoil tillage resulted in decreases in water consumption by 6.3–7.8% and increases in maize yield by 644.5–673.9 kg ha-1, soil water content by 2.9–3.0%, and WUE by 12.7–15.2%. Chopped straw mulching led to higher yield,soil water content, and WUE as well as lower water consumption than prostrate whole straw mulching. Mulching with 50% chopped straw had the largest positive effects on maize yield, soil water content, and WUE among the five mulching treatments. Tillage had greater influence on maize yield than straw mulching, whereas straw mulching had greater influence on soil water content, water consumption, and WUE than tillage. These results suggest that 50% chopped straw mulching with subsoil tillage is beneficial in spring maize production aiming at high yield and high WUE in the Huang–Huai–Hai valley.

The causes and impacts for heat stress in spring maize during grain filling in the North China Plain--A review

High-temperature stress （HTS） at the grain-filling stage in spring maize （Zea mays L.） is the main obstacle to increasing productivity in the North China Plain （NCP）. To solve this problem, the physiological mechanisms of HTS, and its causes and impacts, must be understood. The HTS threshold of the duration and rate in grain filling, photosynthetic characteristics （e.g., the thermal stability of thylakoid membrane, chlorophyll and electron transfer, photosynthetic carbon assimilation）, water status （e.g., leaf water potential, turgor and leaf relative water content） and signal transduction in maize are reviewed. The HTS threshold for spring maize is highly desirable to be appraised to prevent damages by unfavorable temperatures during grain filling in this region. HTS has negative impacts on maize photosynthesis by damaging the stability of the thylakoid membrane structure and degrading chlorophyll, which reduces light energy absorption, transfer and photosynthetic carbon assimilation. In addition, photosynthesis can be deleteriously affected due to inhibited root growth under HTS in which plants decrease their water-absorbing capacity, leaf water potential, turgor, leaf relative water content, and stomatal conductance. Inhibited photosynthesis decrease the supply of photosynthates to the grain, leading to falling of kernel weight and even grain yield. However, maize does not respond passively to HTS. The plant transduces the abscisic acid （ABA） signal to express heat shock proteins （HSPs）, which are molecular chaperones that participate in protein refolding and degradation caused by HTS. HSPs stabilize target protein configurations and indirectly improve thylakoid membrane structure stability, light energy absorption and passing, electron transport, and fixed carbon assimilation, leading to improved photosynthesis. ABA also induces stomatal closure to maintain a good water status for photosynthesis. Based on understanding of such mechanisms, strategies for alleviating HTS at the grain-filling stage in spring maize are summarized. Eight strategies have the potential to improve the ability of spring maize to avoid or tolerate HTS in this study, e.g., adjusting sowing date to avoid HTS, breeding heat-tolerance varieties, and tillage methods, optimizing irrigation, heat acclimation, regulating chemicals, nutritional management, and planting geometric design to tolerate HTS. Based on the single technology breakthrough, a com- prehensive integrated technical system is needed to improve heat tolerance and increase the spring maize yield in the NCP.

A preliminary study of the effects of plastic film-mulched raised beds on soil temperature and crop performance of early-sown short-season spring maize(Zea mays L.) in the North China Plain

To identify a strategy for earlier sowing and harvesting of spring maize(Zea mays L.) in an alternative maize–maize double cropping system, a 2-year field experiment was performed at Quzhou experimental station of China Agricultural University in 2014 and 2015. A short-season cultivar, Demeiya number 1(KX7349), was used in the experiment. Soil temperature to 5 cm depth in the early crop growth stage, crop growth, crop yield, and water use of different treatments(plastic film-mulched raised bed(RF) and flat field without plastic film mulching(CK) in 2014; RF, plastic film-mulched flat field(FF), and CK in 2015)were measured or calculated and compared. Soil temperature in the film-mulched treatments was consistently higher than that in CK(1.6–3.5 °C in average) during the early growth stage. Crops in plastic film-mulched treatments used 214 fewer growing-degree days(GDDs) in 2014 and 262 fewer GDDs in 2015. In 2014, the RF treatment yielded 32.7%higher biomass than CK, although its 9.4% higher grain yield was not statistically significant. Also, RF used 17.9% less water and showed 33.1% higher water use efficiency(WUE) than CK. In 2015, RF and FF showed 56.2% and 49.5% higher yield, 15.0% and 4.5%lower water use(ET), and 63.4% and 75.7% higher WUE, respectively, than CK. RF markedly increased soil temperature in the early crop season, accelerated crop growth, reduced ET,and greatly increased crop yield and WUE. Compared with FF, RF had no obvious effect on crop growth rate, although soil temperature during the period between sowing and stem elongation was slightly increased. However, RF resulted in lower ET and higher WUE than FF. Effects of RF on soil water dynamics as well as its cost-effectiveness remain topics for further study.

A STATISTICAL PREDICTION MODEL FOR SPRING RAINFALL OVER NORTHERN CHINA BASED ON THE INTERANNUAL INCREMENT APPROACH

The spring (March-April-May) rainfall over northern China (SPRNC) is predicted by using the interannual increment approach. DY denotes the difference between the current year and previous years. The seasonal forecast model for the DY of SPRNC is constructed based on the data that are taken from the 1965-2002 period (38 years), in which six predictors are available no later than the current month of February. This is favorable so that the seasonal forecasts can be made one month ahead. Then, SPRNC and the percentage anomaly of SPRNC are obtained by the predicted DY of SPRNC. The model performs well in the prediction of the inter-annual variation of the DY of SPRNC during 1965-2002, with a correlation coefficient between the predicted and observed DY of SPRNC of 0.87. This accounts for 76% of the total variance, with a low value for the average root mean square error (RMSE) of 20%. Both the results of the hindcast for the period of 2003-2010 (eight years) and the cross-validation test for the period of 1965-2009 (45 years) illustrate the good prediction capability of the model, with a small mean relative error of 10%, an RMSE of 17% and a high rate of coherence of 87.5% for the hindcasts of the percentage anomaly of SPRNC.

Estimates of N_2O Emissions and Mitigation Potential from a Spring Maize Field Based on DNDC Model

Agricultural production plays an important role in affecting atmospheric nitrous oxide （N20） concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years （2009 and 2010） to estimate NzO emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition （DNDC）, for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N20 emissions from the target field. The results showed that the major N20 pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N20 emissions each year. Rainfall and fertilizer application were the major factors influencing the N20 emissions from spring maize field. The average N20 flUXeS from the CK （control plot, without fertilization） and FP （traditional chemical N fertilizer） treatments were 23.1 and 60.6 gg m-2 h-~ in 2009, respectively, and 21.5 and 64.3 gg m-2 h-~ in 2010, respectively. The emission factors （EFs） of the applied N fertilizer （270 kg N ha-1） as N20- N were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily NzO emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N20 emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N20 emissions from spring maize production in Northeast China.

Combined Impact of Climate Change, Cultivar Shift, and Sowing Date on Spring Wheat Phenology in Northern China

Distinct climate changes since the end of the 1980s have led to clear responses in crop phenology in many parts of the world. This study investigated the trends in the dates of spring wheat phenology in relation to mean temperature for different growth stages. It also analyzed the impacts of climate change, cultivar shift, and sowing date adjustments on phenological events/phases of spring wheat in northern China （NC）. The results showed that significant changes have occurred in spring wheat phenology in NC due to climate warming in the past 30 years. Specifically, the dates of anthesis and maturity of spring wheat advanced on average by 1.8 and 1.7 day （10 yr）-1. Moreover, while the vegetative growth period （VGP） shortened at most stations, the reproductive growth period （RGP） prolonged slightly at half of the investigated stations. As a result, the whole growth period （WGP） of spring wheat shortened at most stations. The findings from the Agricultural Production Systems Simulator （APSIM）-Wheat model simulated results for six representative stations further suggested that temperature rise generally shortened the spring wheat growth period in NC. Although the warming trend shortened the lengths of VGP, RGP, and WGP, the shift of new cultivars with high accumulated temperature requirements, to some extent, mitigated and adapted to the ongoing climate change. Furthermore, shifts in sowing date exerted significant impacts on the phenology of spring wheat. Generally, an advanced sowing date was able to lower the rise in mean temperature during the different growth stages （i.e., VGP, RGP, and WGP） of spring wheat. As a result, the lengths of the growth stages should be prolonged. Both measures （cultivar shift and sowing date adjustments） could be vital adaptation strategies of spring wheat to a warming climate, with potentially beneficial effects in terms of productivity.

Evaluation of Agricultural Climatic Resource Utilization During Spring Maize Cultivation in Northeast China Under Climate Change

Agricultural climatic resources （such as light,temperature,and water） are environmental factors that affect crop productivity.Predicting the effects of climate change on agricultural climatic resource utilization can provide a theoretical basis for adapting agricultural practices and distributions of agricultural production.This study investigates these effects under the IPCC （Intergovernmental Panel on Climate Change） scenario A1B using daily data from the high-resolution RegCM3 （0.25° ×0.25°） during 1951-2100.Model outputs are adjusted using corrections derived from daily observational data taken at 101 meteorological stations in Northeast China between 1971 and 2000.Agricultural climatic suitability theory is used to assess demand for agricultural climatic resources in Northeast China during the cultivation of spring maize.Three indices,i.e.,an average resource suitability index （Isr）,an average efficacy suitability index （Ise）,and an average resource utilization index （K）,are defined to quantitatively evaluate the effects of climate change on climatic resource utilization between 1951 and 2100.These indices change significantly in both temporal and spatial dimensions in Northeast China under global warming.All three indices are projected to decrease in Liaoning Province from 1951 to 2100,with particularly sharp declines in Isr,Ise,and K after 2030,2021,and 2011,respectively.In Jilin and Heilongjiang provinces,Isr is projected to increase slightly after 2011,while Ise increases slightly and K decreases slightly after 2030.The spatial maxima of all three indices are projected to shift northeastward.Overall,warming of the climate in Northeast China is expected to negatively impact spring maize production,especially in Liaoning Province.Spring maize cultivation will likely need to shift northward and expand eastward to make efficient use of future agricultural climatic resources.

基于CERES-Maize模型的华北平原玉米生产潜力的估算与分析

在对DSSAT4.0中CERES-Maize模型进行参数校正和验证的基础上,进一步利用华北地区具有代表性的10个气象站30年(1976～2005年)的气象资料以及华北地区典型的土壤数据展开模拟。结果表明,在一年一季的生产条件下,华北平原各地区玉米多年平均光温生产潜力为13.53～22.56t/hm2;各地区玉米产量在4月下旬至6月中旬的播期范围内均呈随播期的延迟而增加的趋势,对这一趋势和各气象指标进行相关分析表明,在华北北部主要驱动因子是灌浆期平均日辐射量,而华北中南部主要驱动因子是灌浆期的温度。华北平原自北向南,优化播期呈逐渐推迟的趋势:北部怀来地区5月上旬播种较为适宜,北京、乐亭和天津地区以5月下旬至6月初播种产量最高;中南部以6月中上旬播种(夏播)较适宜。

东北地区未来春玉米干旱风险时空分布及对气候变化的响应

【目的】干旱是影响中国农业生产的主要自然灾害之一。东北地区作为中国最大的玉米生产基地,气候变化背景下干旱频发重发严重影响玉米的高产稳产。评估未来气候情景下东北地区春玉米干旱发生风险及其空间格局变化,为该地区春玉米防旱避灾以及保障其高产稳产提供科学依据。【方法】选取东北地区春玉米潜在种植区为研究区域,基于ISIMIP输出的SSP1-2.6、SSP3-7.0和SSP5-8.53种气候情景的1981—2060年逐日气象资料以及53个农业气象观测站1981—2014年春玉米生育期资料,选取作物水分亏缺指数(crop water deficit index,CWDI)为农业干旱指标,分析东北地区春玉米不同生育时期不同等级干旱时空分布特征,选择最优概率理论分布函数进行干旱指数序列的概率估算,基于信息扩散理论估算得到各点春玉米不同等级干旱风险,构建干旱风险指数,评估未来不同气候情景下东北地区春玉米干旱发生风险及未来各等级风险区的空间格局变化。【结果】(1)1981—2014年东北地区春玉米全生育期干旱指数总体呈西南高东北低的特征,表现为内蒙古东四盟(57.3%)>黑龙江省(40.6%)>辽宁省(39.5%)>吉林省(38.9%)。(2)研究区域春玉米生育中期干旱指数整体高于生育前期和生育后期。其中,2030s和2050s研究区域春玉米生育前期干旱风险概率为轻旱>中旱≈重旱>特旱,生育中期干旱风险概率为特旱>重旱>轻旱≈中旱,生育后期干旱风险概率轻旱>中旱>重旱>特旱。(3)1981—2060年,SSP1-2.6低排放情景下,东北地区春玉米较高等级干旱风险发生概率将减少,极高和较高干旱风险区明显向西南收缩,2030s和2050s面积占比分别减少5.4%和9.6%、0.8%和2.5%;而SSP3-7.0和SSP5-8.5两个高排放情景下,较高等级干旱风险发生概率增加,且较高干旱风险区向东北扩张,2050s面积占比分别增加8.5%和9.7%。【结论】基于干旱风险指数的未来干旱风险时空分布格局中,东北春玉米干旱风险呈现由西南向东北减少的特征,且未来SSP3-7.0和SSP5-8.5情景下,较高干旱风险区向东北方向扩张,需关注作物关键生育时期提出针对性的防御措施。

中国北方地区植被春季光合物候对气候因素的响应

[目的]探究植被春季光合物候(SOS)的时空变化趋势,揭示气候因素对其影响贡献,为区域植被固碳能力提升提供科学依据。[方法]以中国北方地区为例,基于日光诱导叶绿素荧光反演的总初级生产力数据(GOSIF-GPP)、气象数据等分析了该地区2001—2020年SOS的变化特征,并揭示了其对不同气候因素(如最低气温、最高气温、降水和太阳辐射)的响应差异。[结果](1)中国北方地区SOS的平均值主要出现在第105~150天,较晚的SOS主要分布在青海和内蒙古中东部。(2)2001—2020年区域年平均SOS呈显著提前趋势(p<0.05),变化幅度为-0.31 d/a,且不同植被类型的SOS均呈显著提前趋势(p<0.05)。(3)SOS对4个气候因素呈负敏感性,特别是最高气温和最低气温是影响SOS变化的重要气候因素,反映了气温升高有利于中国北方大部分地区SOS提前。[结论]中国北方地区SOS变化具有异质性,且气温是影响SOS变化的主要因素。

西北干旱区气候变化对灌溉春玉米生产的影响

基于河西走廊中部1984-2022年灌溉春玉米定位观测试验,结合同期气象资料,采用线性回归、相关分析和M-K突变检验等方法,分析气候变化对西北干旱区灌溉春玉米生育期和产量的影响。结果表明:春玉米全生育期平均气温以0.76℃·10a^(-1)的速率呈极显著上升趋势(P<0.01)。≥10℃活动积温呈显著增加趋势,平均每10a增加135.80℃·d。全生育期降水量增加趋势不显著,但乳熟-成熟期以4.50mm·10a^(-1)的速率显著增加(P<0.05)。1984-2004年日照时数以126.88h·10a^(-1)的速率显著增多,近19a以109.38h·10a^(-1)的速率显著减少。1984-2004年春玉米生长期长度以9.86d·10a^(-1)的速率显著延长,近19a以7.39d·10a^(-1)的速率显著缩短。播种-出苗期和七叶-拔节期长度与气温呈显著负相关;播种-出苗期、三叶-七叶期和吐丝-乳熟期长度与降水量呈显著正相关;各生育期长度均与日照时数呈显著正相关。研究期内春玉米产量呈波动变化,气候产量与全生育期内降水量呈显著负相关。综上所述,西北干旱区气候变化对当前灌溉方式下的春玉米生产不利。

2021-2022年华北四省夏玉米产区玉米商业品种鉴定数据集

玉米是我国第一大粮食作物,年产量约占全国粮食总产量的四成,精准鉴定并掌握我国玉米主产区商业品种生长特性,对充分挖掘和保护优异种质资源,有效筛选最优且最适宜种植的品种,实现玉米高产栽培目标至关重要。基于此,本数据集提供了在我国华北地区四省夏玉米区开展的188个玉米商业品种的生育期、株高、抗性、产量等27种重要特性数据,时间分辨率为日尺度,数据范围为2021、2022年。数据采集和处理过程严格遵循测量仪器数据质量控制和规范。数据以产区为尺度公开,以期为各玉米产区充分挖掘并使用优异玉米种质资源提供依据。

陕北榆林滴灌春玉米不同生育期适宜土壤水分控制界限研究

【目的】确定陕北榆林滴灌春玉米各生育期适宜的土壤水分界限,得到该地区滴灌春玉米的灌溉制度。【方法】采用正交试验设计方法,在春玉米苗期、拔节期、抽雄期、灌浆期、成熟期5个生育期设置4种灌溉水平,探究不同灌水方案对滴灌春玉米的生长及水分利用效率的影响。【结果】(1)陕北榆林滴灌春玉米关键生育期为拔节期、抽雄期。苗期、灌浆期及成熟期为非关键期。在拔节期和抽雄期适当降低灌溉水平更有利于春玉米后续生长发育;(2)综合各灌水方案对春玉米株高、茎粗、叶面积指数和产量的影响,最优的田间土壤水分控制界限为:苗期适宜土壤水分界限为59%~79%FC(FC代表土壤田间持水率),拔节期为70%~90%FC,抽雄期为68%~88%FC,灌浆期为56%~76%FC,成熟期为49%~69%FC。【结论】最优的灌溉制度为全生育期灌水9次,即苗期2次(m=20 mm),拔节期3次(m_(1)=20 mm,m_(2)=m_(3)=30 mm),抽雄期3次(m_(1)=m_(2)=m_(3)=30 mm),灌浆期1次(m=25 mm),成熟期不灌水,综合灌溉定额为235 mm。该制度下春玉米产量为14664 kg/hm^(2),水分利用效率达3.01 kg/m^(3)。较对照组产量提高15.56%,WUE提高19.19%。该研究结果对陕北榆林滴灌春玉米田间水分管理具有重要指导意义。

Spatio-temporal dynamics of maize cropping system in Northeast China between 1980 and 2010 by using spatial production allocation model

Understanding crop patterns and their changes on regional scale is a critical re- quirement for projecting agro-ecosystem dynamics. However, tools and methods for mapping the distribution of crop area and yield are still lacking. Based on the cross-entropy theory, a spatial production allocation model （SPAM） has been developed for presenting spa- tio-temporal dynamics of maize cropping system in Northeast China during 1980-2010. The simulated results indicated that （1） maize sown area expanded northwards to 48~N before 2000, after that the increased sown area mainly occurred in the central and southern parts of Northeast China. Meanwhile, maize also expanded eastwards to 127°E and lower elevation （less than 100 m） as well as higher elevation （mainly distributed between 200 m and 350 m）; （2） maize yield has been greatly promoted for most planted area of Northeast China, espe- cially in the planted zone between 42°N and 48°N, while the yield increase was relatively homogeneous without obvious longitudinal variations for whole region; （3） maize planting density increased gradually to a moderately high level over the investigated period, which reflected the trend of aggregation of maize cultivation driven by market demand.

“十三五”国家东华北春玉米区域试验品种抗病性评价

病害是影响玉米生产的重要生物逆境,培育抗病品种是玉米病害防控最为经济、有效和环保的策略。本研究以我国“十三五”期间国家东华北春玉米区域试验(中早熟、中熟和中晚熟3个熟期组)中724份(次)参试品种的病害鉴定数据进行分析,病害包括玉米大斑病、丝黑穗病、禾谷镰孢茎腐病、灰斑病和禾谷镰孢穗腐病。结果表明,5种病害抗性级别以中抗和感病为主,中早熟、中熟和中晚熟组的这2个级别分别占总数的82.94%、84.12%和72.46%;中晚熟组抗性强于中熟和中早熟,中早熟、中熟和中晚熟组达到中抗(MR)以上的品种分别占总数的50.24%、56.37%和69.33%,其中,达高抗(HR)的分别占4.52%、4.41%和7.84%,达抗(R)的分别占8.73%、10.59%和18.88%;大斑病和灰斑病的抗原较为缺乏,均无高抗品种,中早熟组达到抗(R)以上水平的病害排序从高到低是禾谷镰孢茎腐病、丝黑穗病、禾谷镰孢穗腐病、灰斑病和大斑病,中熟组排序是禾谷镰孢穗腐病、禾谷镰孢茎腐病、丝黑穗病、灰斑病和大斑病,中晚熟组排序是禾谷镰孢穗腐病、禾谷镰孢茎腐病、丝黑穗病、大斑病和灰斑病;年际间鉴定结果受气候环境影响较大,2020年总体表现较差;中早熟、中熟和中晚组5种病害同时达到中抗(MR)以上的品种分别占2.78%、6.37%和15.67%,但最终仅有1个品种(承玉88)通过审定,说明高产抗病绿色玉米品种选育难度较大,建议设立抗病绿色玉米品种试验组别,强化抗病绿色玉米品种审定标识,有效快速推动绿色品种的选育与推广。本研究明确了近年来我国东华北春玉米试验品种的主要病害抗性水平,为今后品种选育、审定与推广提供参考依据,从而支撑我国玉米种业绿色发展。

华北北部夏玉米适期早播的增产效果

播期调整是直接有效减缓气候变化对农业负面影响的重要措施,为了揭示播期变化对作物产量形成的影响机制,在华北北部的河北固城农业气象国家野外科学观测研究站,于2019—2021年设置早播10 d、晚播10 d、晚播20 d和正常播期4个播期,进行了夏玉米同一品种播期调整的大田试验,监测其生育期变化、植株干物质累积、叶片光合特性和籽粒灌浆特征,以及成熟期取样测定产量构成等要素。结果表明:夏玉米播期提前,苗期、穗期及全生育期延长,尤其有效灌浆持续日数随播期提前而延长,播期每提前10 d有效灌浆持续日数延长4.7 d,播期提前10 d平均灌浆速率比对照和晚播10,20 d的平均偏高4.04%,籽粒灌浆、累积增加,百粒质量提高5.459 g。夏玉米穗粒数、穗粒质量、百粒质量等主要产量构成要素在不同播期间存在显著差异,且随播期提前而递增,在6月8日—7月8日试验期理论产量随播期每提前10 d增产速率为1395.4 kg/hm ^(2)。夏玉米关键生育期平均叶片净光合速率(Pn)随播期每提前10 d提高0.764μmol/(m 2·s),播期提前10 d比对照和晚播10,20 d的平均Pn提高7.31%。光合速率提高使得干物质生产、积累及向籽粒转运量增加,穗粒质量、百粒质量分别比对照和晚播10,20 d的平均偏高24.01%,18.00%。播期提前,株高低,茎秆粗壮,抗倒伏,个体绿叶面积大,群体叶面积指数(LAI)高,叶片光合作用能力高,播期每提前10 d成熟期地上干物质分配率:籽粒质量递增率2.26%,植株营养器官—果穗籽粒间干物质的源—库分配关系改变,穗粒质量、百粒质量提高和籽粒增产。研究认为:华北地区冬小麦—夏玉米一年两熟区充分利用气候变暖增加的热量资源,合理调配茬口,夏玉米适期早播,延长生育期和籽粒灌浆时间,可有效提高单产。

2023年春季我国气候异常特征及成因分析

2023年春季(3—5月),全国平均气温为11.5℃,为1961年以来历史同期第七高。除新疆、西北地区西部、西藏等地气温偏低外,我国大部分地区气温均偏高。全国平均降水量为132.7 mm,较常年同期偏少7.4%。降水呈现“北多南少”的特征,华北、黄淮及青藏高原等地降水偏多,东北、江南东部、华南和西南地区降水显著偏少。在对流层中层,春季亚欧中高纬度呈现“两脊一槽”分布,乌拉尔山地区为正高度距平中心,贝加尔湖至巴尔喀什湖为高度场负距平中心,而东北亚上空为位势高度场正异常;西太平洋副热带高压强度较常年偏弱;在对流层低层,热带西太平洋地区维持异常气旋性环流,其以北则为异常反气旋性环流。2023年春季东北亚高压脊指数为1.7,超过1个标准差,为1961年以来第四强,其异常偏强有利于我国北方降水偏多。长江以北地区受反气旋环流影响,异常偏东南风强盛,有利于将西北太平洋的暖湿水汽输送至我国北方地区。赤道中东太平洋自2021年9月开始一次弱La Ni?a事件,该事件一直持续至2023年3月结束,4月赤道中东太平洋海温开始转为暖水位相。2023年春季我国北方降水异常偏多受到赤道中东太平洋海温演变的影响,合成分析表明,在海温由冷转暖的春季,欧亚中纬度地区易出现“两脊一槽”的环流异常分布型,中西路冷空气南下影响我国,同时东亚上空反气旋式环流使得我国北方地区受异常东南风控制,西北太平洋水汽向北输送偏强,为北方地区的降水提供有利条件。

宝鸡市北部山区春玉米施肥效果研究

为进一步推广配方肥及缓控释肥料在春玉米主产区的应用,探究春玉米化肥减量增效的施肥方案。分别在宝鸡市北部山区千阳、陇县、麟游三县区设置试验点,每个试验点依次设4个处理:25(N)-10(P 2O 5)-5(K 2O)配方肥40 kg/667 m^(2)和50 kg/667 m^(2)、28(N)-16(P 2O 5)-6(K 2O)40 kg/667 m^(2)和27(N)-13(P 2O 5)-6(K 2O)缓控释配方肥40 kg/667 m^(2),各处理肥料均作为底肥一次施入。收获后考种,测定株高、穗长、穗位高、穗粒数、百粒重及籽粒含水量,按14%的自然含水量计算出籽率,折算成667 m^(2)产量。运用excel进行双因素无重复方差分析,LSD法进行多重比较。结果表明,千阳、麟游两个试验点处理4产量最高,陇县试验点处理3产量最高,但与处理4差异不显著。三个试验点不同处理667 m^(2)纯收益处理4最高,为1430.89元/667 m^(2),处理1最低,为1286.98元/667 m^(2)。处理4相对处理1的新增投入产出比最高,为1:8.21。施用缓控释肥料可以提高春玉米产量及收益,27(N)-13(P_(2)O_(5))-6(K_(2)O)缓控释配方肥40 kg/667 m^(2)或相近的施肥方案较为适合在宝鸡北部山区县推广。

土壤水分上下限对北疆滴灌春玉米产量和品质的影响

为确定滴灌春玉米(Zea mays L.)各生育期适宜的土壤水分上、下限,从而为新疆玉米灌溉管理升级提供理论依据,以“太玉339”为试材,采用正交试验设计方法,在玉米拔节期、扬花-灌浆期、灌浆-完熟期分别设置3种水分上、下限(50%~80%FC、60%~90%FC、70%~100%FC,FC为田间持水量),共设9个处理(T_(1)~T_(9)),分析其对春玉米不同生育阶段的生长指标、产量、品质、水分利用效率(WUE)的影响。结果表明:当玉米各生育期土壤水分保持在50%~80%FC时,其株高、地上干物质量、叶面积指数(LAI)和产量均显著减小,但会提高水分利用效率(WUE)。总体而言,T_(3)处理的产量最高,为17114.51 kg/hm^(2);T_(4)处理的WUE最高,为3.11 kg/m^(3);在灌浆-完熟期提高水分上、下限有利于增加玉米粗蛋白、粗脂肪及淀粉的含量,其中T_(3)处理该3个指标均为最高,分别为11.02、4.11、69.96 g/100g。以产量、干物质积累量、品质、WUE为指标,基于熵权法的综合评价表明T_(3)处理最优。综上所述,新疆北疆地区滴灌春玉米在拔节期、扬花-灌浆期、灌浆-完熟期适宜的土壤水分分别为50%~70%FC、70%~100%FC、70%~100%FC。

通过种植制度改革实现黄淮海北部地区玉米机械籽粒直收

【目的】机械粒收是玉米收获技术发展的方向。在“冬小麦-夏玉米”一年两季轮作种植制度下,黄淮海北部地区热量资源不足,玉米生长季节有限,收获时籽粒含水率高,难以进行机械粒收,是世界上玉米机械粒收技术应用难度最大的区域,探索玉米机械粒收的可行性对推动区域玉米生产全程机械化和玉米产业提质增效、提升竞争力具有重要意义。【方法】2016—2017年在新乡、2018年在北京分别对郑单958、先玉335、迪卡517、京农科728和丰垦139等不同熟期品种的籽粒脱水积温需求进行系统观测;利用黄淮海北部地区近10年气象数据,以冬前预留500℃·d积温为小麦适宜播期,按玉米生长季节活动积温(≥0℃)100℃为梯度,将其划分为7个积温带;将区域热量资源条件和不同品种籽粒脱水积温需求进行定量匹配分析。【结果】在玉米正常夏播条件下,随着品种熟期提早,各供试品种在黄淮海北部地区达到生理成熟并且可以实现粒收的区域逐渐向北扩展,一般比小麦适宜播期推迟5—10 d,但是区域内北端和西端的积温带Ⅰ—Ⅲ(1900—2800℃·d)的热量资源仍无法满足熟期较早的京农科728和丰垦139籽粒含水率下降至25%甚至是达到生理成熟的积温需求。将冬小麦-夏玉米一年两熟改为夏玉米-春玉米-冬小麦两年三熟制后,玉米春播和夏播各供试品种籽粒含水率都能下降至25%以下实现机械粒收,如果选择熟期较早的品种,在冬小麦或春玉米播种前还可以通过田间站秆脱水延迟收获,使籽粒含水率进一步降至20%以下,提高粒收质量,降低烘干成本。【结论】通过种植制度改革可以有效解决黄淮海北部地区玉米生长季节热量不足、收获时期含水率过高导致的玉米成熟度差、容重低、易霉变和机械粒收难度大的问题,实现提质增效。