镉低积累小麦品种的筛选研究

低吸收重金属作物品种的筛选已经成为重金属污染农田的主要修复方式之一。【目的】筛选镉低积累冬小麦品种。【方法】针对华北平原种植结构,于2017年10月15日在河南省北部某地区进行田间小区试验,采用人工拉沟点播方式播种。研究了47个不同品种冬小麦对重金属镉吸收的差异性。【结果】重金属镉在不同品种冬小麦各部位的量的顺序均为根>茎叶>籽粒,且镉的转运系数和富集系数均小于1,转运系数介于0.10～0.60之间,富集系数介于0.002～0.060之间。不同品种冬小麦籽粒中重金属含镉量介于0.004～0.130之间,相差35.28倍。筛选出籽粒含镉量符合国家标准(GB2715—2016,≤0.10 mg/kg)的品种42个,占所有品种的89.36%,有5个品种籽粒含镉量超过国家标准。冬小麦不同品种间对镉的吸收显示出巨大的差异性。【结论】在重金属镉轻度污染碱性土壤条件下,多数冬小麦品种籽粒含镉量并未超标。     

Best management practices of tillage and nitrogen fertilization in Mediterranean rainfed conditions: Combining field and modelling approaches

In this work, appropriate management practices for crop production under the variable climate conditions of the Mediterranean region, in particular rainfall, were tested with the use of a modelling system applied to long-term (i.e. 18 years) field data. The calibration of the CropSyst model was performed using data collected from 1996 to 1999 at three different Mediterranean locations (i.e., HYP-Guissona, MYP-Agramunt and LYP-Candasnos, i.e. high, medium and low yield potential, respectively) within a degree of yield potential. The model simulated reasonably well barley growth and yield to different tillage and N fertilization strategies.Simulations of barley performance over 50 years with generated weather data showed that yields were often greater and never smaller under no-tillage compared to conventional tillage with a mean increase of 36%, 63% and 18% for HYP-Guissona, MYP-Agramunt and LYP-Candasnos. In MYP-Agramunt, the long-term data showed a 40% increase in grain yields when using no-tillage compared to conventional tillage, as an average of 18 years.The model also predicted that greater N applications in no-tillage were appropriate to take advantage of additional water supply. Taking into account the limited amount of soil water available, overall N fertilizer applications could be reduced to about half of the traditional rate applied by the farmers without yield loss. The 50-yr simulation, confirmed by the long-term experimental data, identified no-tillage as the most appropriate tillage practice for the rainfed Mediterranean areas. Also, N fertilization must be reduced significantly when tillage is used or when increasing aridity. Our work demonstrates the usefulness of the combination of long-term field experimentation and modelling as a tool to identify the best agricultural management practices. It also highlights the importance of posterior analysis with long-term observed field data to determine the performance of simulation results.     

Responses of soil properties,root growth and crop yield to tillage and crop residue management in a wheat–maize cropping system on the North China Plain

Crop residue removal and subsoil compaction are limiting to yield improvement in the North China Plain (NCP). We conducted a field study composed of six consecutive crop growing seasons from 2010 to 2013 in Henan province, China, to determine responses of soil properties, crop root distribution and crop yield to tillage and residue management in a wheat–maize cropping system under irrigated conditions. Tillage practices comprised mouldboard ploughing (MP) to a depth of 15-cm, deep mouldboard ploughing (DMP) to a depth of 30-cm, and chisel ploughing (CP) to a depth of 30-cm. Crop residue management included crop residue retained (CRRet) and crop residue removed (CRRem). The results indicated that yields in DMP and CP increased by 6.0% and 7.3% for wheat and by 8.7% and 9.0% for maize, respectively, relative to MP. The CRRet treatment also increased wheat yield by 6.7% and maize yield by 5.0%. The yield increases under DMP and CP were related to reduced bulk density and soil penetration resistance, increased soil water content, improved total N distribution and improved root density (0–60-cm). Compared with MP, the root mass density under DMP and CP were increased by 43.4% and 42.0% for wheat and by 40.6% and 39.4% for maize, respectively. The yield increases under CRRet were also related to increased soil water content, reduced penetration resistance and increased N status (0–40-cm). Overall, for DMP + CRRet and CP + CRRet, a more favorable soil environment alongside greater root mass density and suitable spatial distribution resulted in higher grain yields of wheat and maize. Thus, compared with conventional shallow tillage practice, DMP or CP with residue application could improve soil quality and agricultural productivity under irrigated areas with loam soil in the NCP.     

玉米免耕播种机械化技术推广前景

根据项目试验示萍点的对比试验结果,探讨玉米免耕播种机械化技术在沈阳地区的应用效果,结合沈阳市玉米生产的实际情况,提出推广应用此技术过程中存在的问题及解决措施,为促进农业生产可持续发展提供参考。     

耕整地机械的发展与推广探讨

我国耕整地机械技术水平较低,推广程度也有待提升。针对当前我国耕整地机械的发展现状,分析我国耕整地机械使用中存在的问题,提出促进我国耕整地机械发展与推广的措施,以期为我国耕整地机械的研发与应用提供参考。     

缺Fe预处理对Fe、Cd根际吸附与水稻吸收和转运的影响

采用蛭石-营养液联合培养试验,测定并比较了缺Fe预处理和正常Fe营养供应下水稻根际pH值、Eh、根际蛭石和根表吸附的Fe、Cd数量,及根系分泌的低分子量有机酸(LMWOAs)种类与数量,探讨了缺Fe预处理下的根际性状和LMWOAs对根际Fe、Cd吸附与水稻吸收转运的影响。结果表明,缺Fe预处理后水稻根际酸度增加,根际还原性增强,稻根分泌的低分子量有机酸降低;根际蛭石表面吸附的Fe变化不大,而稻根表面吸附沉积的Fe减少,根际蛭石非结晶态Cd含量增加,根表Fe膜中的Cd含量升高但不显著,水稻根系Cd含量和积累量上升,说明缺Fe减少了两种元素在根际和根表吸附位点的竞争,但由于Fe膜对Cd的阻挡作用有限,促进了水稻对Cd的吸收。不过,缺Fe导致水稻根部向地上部转运的Cd、Fe下降,可能与根内低分子量有机酸载体数量的下降有关。     

辽宁地区日本栗养分用量与分配研究

为科学地指导栗树施肥,该文研究了嫁接6~8年生大峰和辽栗10号各器官的年生物量及其分配比例,测定了2个品种各器官的养分含量,计算单株所需养分用量及其相应施肥量。结果表明:嫁接6~8年生栗树的单株平均生物量为:10.64、19.97、29.75 kg,生物量年均递增率达76.59%,同立地、年龄,不同品种间生物量差异很大;在干枝、根、叶、果肉、刺苞、1年生枝、果壳、雄花中的分配依次降低。嫁接7~8年生栗树单株年间养分(N、P2O5、K2O、Ca、Mg)平均吸收量分别为175.87、34.55、68.21、170.88、31.13 g。盛果初期,栗树分配于生殖生长的养分量逐年加大,各器官中,N、P2O5用量最多的是叶片,K2O用量最多的是果肉;树体内各营养元素吸收量占总量的排序NCaKPMg。根据试验分析:每生产100 kg鲜栗果,树体需要施N 3.06 kg、P5O21.50 kg、K2O 1.48 kg,N:P5O2:K2O=2:1:1。这一指标可作为辽宁地区日本栗的科学施肥依据。     

年内轮耕对小麦—玉米两熟农田土壤水稳性团聚体碳、氮分布的影响

在华北平原小麦—玉米两熟区,设置6种年内轮耕模式,即小麦季免耕玉米季免耕(WZ-MZ)、小麦季免耕玉米季深松(WZ-MS)、小麦季深松玉米季免耕(WS-MZ)、小麦季深松玉米季深松(WS-MS)、小麦季翻耕玉米季免耕(WC-MZ)、小麦季翻耕玉米季深松(WC-MS),探讨年内轮耕模式对土壤水稳性团聚体碳、氮分布的影响。结果表明,MS的年内轮耕模式比MZ有利于0~40 cm土层微团聚体聚成更大粒级的团聚体和保护大团聚体免受破坏;无论玉米季免耕还是深松条件下,与WZ、WC相比,WS能提高10~40cm土层0.25 mm粒级的大团聚体含量;WZ和WS比WC能显著提高土壤表层有机碳及全氮,使更多的碳、氮在土壤表层聚集;MS比MZ能降低0~10 cm和提高10~40 cm土层团聚体中有机碳及全氮含量;WZ能显著提高土壤0~10 cm土壤团聚体中C/N;无论小麦季采用哪种耕作方式,MS比MZ能降低0~10 cm和提高10~40 cm土层团聚体中C/N。     

不同种植年限蔬菜大棚土壤盐分累积及硝态氮迁移规律

通过对关中地区泾阳等地32个蔬菜大棚土壤分析,表明:该区大棚土壤盐分表聚和酸化现象明显。耕层(0~20cm)平均全盐量为3.2g/kg,20~40cm土层平均也达2.8g/kg,40~60cm和60~80cm土层在2.0g/kg左右;耕层土壤PH值比对照下降0.61,60~80cm土层比对照下降了0.27;耕层硝态氮含量平均高达63.3mg/kg,是对照的5.5倍,硝态氮深层下迁趋势明显,可达80cm以下,仅60~80cm土层的平均含量为27.3mg/kg;耕层平均有机质含量仅为16.0g/kg。随棚龄延长盐渍化和酸化程度加重,硝酸盐下迁损失愈多。其主要原因是偏施化肥,不重视有机肥,常年连作,不合理灌溉等。建议采取增施有机肥、限制化肥用量、改进施肥技术、科学灌排、轮作倒茬等措施。     

河西灌区免耕秸秆覆盖对春小麦播种及出苗的影响

在河西灌区储水灌溉条件下进行了秸秆覆盖免耕(NTS)、秸秆还田(CTS)和常规耕作(CTB)对春小麦播种出苗影响的试验研究.结果表明,在春小麦的播种期,3种耕作方式的平均日均地温变化趋势一致,均随着土壤深度的增加而减小,且在同一时间NTS的地温小于相同土层CTS和CTB,NTS在5 cm处14∶00的地温比CTS和CTB分别低0.7~4.6℃和1.2~6.1℃.NTS的地温日变化趋势相对缓和.苗期全天5 cm处的地温NTS比CTS和CTB分别低-1.40~2.90℃和-0.60~3.70℃.NTS造成的“低温效应”对种子发芽不利,所以尽管NTS的播种时间比CTB和CTS推迟了一周,但出苗率仍远低于CTS和CTB.