玉米穗轴的颜色变化,是偶然还是与农艺性状存在关联?--以历年国审普通品种为例

玉米穗轴颜色在温带种质及商业化杂交品种中受到强烈的人工选择。为了明确我国不同区域玉米穗轴颜色选择的偏向性,探索轴色与多种农艺性状间的关联,本文以1992—2020年国审普通玉米品种为例,对品种轴色、审定区域及多项农艺性状进行了比较分析。在统计到的1604个品种中,红轴品种占比从1992年的50%逐渐提高至2020年的80%以上。其中,北方春玉米区、黄淮海夏玉米区和西北玉米区的红轴品种比例随年份更替提升速度高于西南和南方玉米区。对比分析红、白轴品种在株型、果穗和籽粒特性等方面的差异发现,近15~20年间的红轴品种平均穗长和穗行数均显著高于白轴。随年代更替,红轴品种的籽粒平均粗淀粉含量升高趋势快于白轴,但其平均粗脂肪含量下降明显,并且红轴品种平均粗蛋白含量和赖氨酸含量表现弱于白轴。因此,针对红色穗轴的强烈人工选择可能主要与玉米单株产量潜力的挖掘有关。但红轴品种在非生物逆境抗性和籽粒品质方面的表现需要进一步探讨。

大型商业综合体模板支撑体系研究

大型商业综合体具有楼层高、结构重、跨度大、轮廓复杂等特点,如何有针对性地处理上述问题是此类工程模板支撑体系设计中的重难点,这要求施工采用高强度的支撑材料、合理的施工方案设计、高效的人员组织及施工安排。因此,承插型盘扣式模板支撑架在商业综合体建设中得到了广泛应用。

Effect of Source-Sink Manipulation on Photosynthetic Characteristics of Flag Leaf and the Remobilization of Dry Mass and Nitrogen in Vegetative Organs of Wheat

The photosynthetic characteristics of flag leaf and the accumulation and remobilization of pre-anthesis dry mass（DM） and nitrogen（N） in vegetable organs in nine wheat cultivars under different source-sink manipulation treatments including defoliation（DF）, spike shading（SS） and half spikelets removal（SR） were investigated. Results showed that the SS treatment increased the photosynthetic rate（Pn） of flag leaf in source limited cultivar, but had no significant effect on sink limited cultivar. The SR treatment decreased the Pn of flag leaf. Grain DM accumulation was limited by source in some cultivars, in other cultivars, it was limited by sink. Grain N accumulation was mainly limited by source supply. The contribution of pre-anthesis dry mass to grain yield from high to low was stem, leaf and chaff, while the contribution of pre-anthesis N to grain N from high to low was leaf, stem and chaff. Cultivars S7221 and TA9818 can increase the contribution of remobilization of DM and N to grain at the maximum ratio under reducing source treatments, which may be the major reason for these cultivars having lower decrease in grain yield and N content under reducing source treatments.

Plastic-film-side seeding,as an alternative to traditional film mulching,improves yield stability and income in maize production in semi-arid regions

Planting under plastic-film mulches is widely used in spring maize production in arid-cold regions for water conservation and warming the soil.To ameliorate the associated issues such as plastic-film residues and additional labor during the“seedling release”in spring maize production,we have developed a plastic-film-side seeding(PSS)technology with the supporting machinery.In the semi-arid regions of Northwest China,a 7-year trial demonstrated that PSS increased plant number per hectare by 6547 and maize yield by 1686 kg ha–1compared with the traditional method of seeding under plastic-film mulch(PM).Two-year experiments were conducted in two semi-arid regions to further understand the effects of PSS on three important aspects of production:(i)the moisture and temperature of soil,(ii)maize development,yield output,and water use efficiency(WUE),and(iii)the revenue and plastic-film residuals in comparison with that of flat planting(CK)and PM.Continuous monitoring of the soil status demonstrated that,compared with CK,the PSS treatment significantly increased the temperature and moisture of the 0–20 cm soil in the seeding row at the early stage of maize development,and it also promoted grain yield(at 884–1089 kg ha^(–1))and WUE,achieving a similar effect as the PM treatment.Economically,the labor inputs of PSS were equal to CK,whereas the PM cost an additional 960 CNY ha–1in labor for releasing the seedlings from below the film.Overall,the PSS system increased profits by 5.83%(547 CNY ha^(–1)yr^(–1))and 8.16%(748 CNY ha^(–1)yr^(–1))compared with CK and PM,respectively.Environmentally,PSS achieved a residual film recovery rate of nearly 100%and eliminated 96 to 130 kg ha^(–1)of residual plastic-film in PM in 3–5 years of maize production.Collectively,these results show that PSS is an eco-friendly technique for improving yield stability and incomes for the sustainable production of maize in semi-arid regions.

Contribution of ear photosynthesis to grain yield under rainfed and irrigation conditions for winter wheat cultivars released in the past 30 years in North China Plain

To understand the contribution of ear photosynthesis to grain yield and its response to water supply in the improvement of winter wheat, 15 cultivars released from 1980 to 2012 in North China Plain（NCP） were planted under rainfed and irrigated conditions from 2011 to 2013, and the ear photosynthesis was tested by ear shading. During the past 30 years, grain yield significantly increased, the flag leaf area slightly increased under irrigated condition but decreased significantly under rainfed condition, the ratio of grain weight：leaf area significantly increased, and the contribution of ear photosynthesis to grain yield changed from 33.6 to 64.5% and from 32.2 to 57.2% under rainfed and irrigated conditions, respectively. Grain yield, yield components, and ratio of grain weight：leaf area were positively related with contribution of ear photosynthesis. The increase in grain yield in winter wheat was related with improvement in ear photosynthesis contribution in NCP, especially under rainfed condition.

心肌梗死溶栓危险指数对急性心肌梗死介入治疗远期预后的评估价值

目的探讨心肌梗死溶栓危险指数(TRI)用于急性心肌梗死介入治疗中对评估远期预后的价值。方法选取2013年1月至2014年1月就诊本院的急性心肌梗死介入治疗患者206例为研究对象,采集3年内死亡病例,其中死亡82例,收集患者的性别、年龄、心率、收缩压、冠脉造影严重程度、TRI,采用单因素分析及logistic回归分析,明确一般资料、疾病情况、TRI与远期病死率间的相关性,然后运用ROC曲线分析确定各个死亡事件相关因素的最佳截断值。结果经统计,LVEF和TRI指数与3年全因死亡存在显著相关性(P<0.05);采用ROC曲线分析,TRI指数用于3年内全因死亡预测的最佳截断值是>22%,而LVEF的最佳截断值是≤54%;TRI的敏感度更高,LVEF的特异性更高,比较ROC曲线下面积,TRI高于LVEF(P<0.05)。结论TRI用于急性心肌梗死介入治疗远期死亡风险的评估效能更高,在护理过程中,应注重对TRI高于22%的患者进行早期护理干预,达到降低远期死亡风险的护理目标。

A simulation of winter wheat crop responses to irrigation management using CERES-Wheat model in the North China Plain

To improve efficiency in the use of water resources in water-limited environments such as the North China Plain（NCP）, where winter wheat is a major and groundwater-consuming crop, the application of water-saving irrigation strategies must be considered as a method for the sustainable development of water resources. The initial objective of this study was to evaluate and validate the ability of the CERES-Wheat model simulation to predict the winter wheat grain yield, biomass yield and water use efficiency（WUE） responses to different irrigation management methods in the NCP. The results from evaluation and validation analyses were compared to observed data from 8 field experiments, and the results indicated that the model can accurately predict these parameters. The modified CERES-Wheat model was then used to simulate the development and growth of winter wheat under different irrigation treatments ranging from rainfed to four irrigation applications（full irrigation） using historical weather data from crop seasons over 33 years（1981–2014）. The data were classified into three types according to seasonal precipitation： 〈100 mm, 100–140 mm, and 〉140 mm. Our results showed that the grain and biomass yield, harvest index（HI） and WUE responses to irrigation management were influenced by precipitation among years, whereby yield increased with higher precipitation. Scenario simulation analysis also showed that two irrigation applications of 75 mm each at the jointing stage and anthesis stage（T3） resulted in the highest grain yield and WUE among the irrigation treatments. Meanwhile, productivity in this treatment remained stable through different precipitation levels among years. One irrigation at the jointing stage（T1） improved grain yield compared to the rainfed treatment and resulted in yield values near those of T3, especially when precipitation was higher. These results indicate that T3 is the most suitable irrigation strategy under variable precipitation regimes for stable yield of winter wheat with maximum water savings in the NCP. The application of one irrigation at the jointing stage may also serve as an alternative irrigation strategy for further reducing irrigation for sustainable water resources management in this area.

Variation of carbon partitioning in newly expanded maize leaves and plant adaptive growth under extended darkness

Plants must maintain a balance between their carbon(C)supply and utilization during the day–night cycle for continuous growth since C starvation often causes irreversible damage to crop production.It is not well known how C fixation and allocation in the leaves of crops such as maize adapt to sudden environmental changes.Here,to quantify primary C fixation and partitioning in photosynthetic maize leaves under extended darkness and to relate these factors to plant growth,maize seedlings were subjected to extended darkness(ED)for three successive days at the 6 th leaf fully expanded stage(V6).ED reduced plant growth and leaf chlorophyll levels but not the rate of net CO_2 exchange.As a result of the reduction in photoassimilates,the accumulation of starch and total soluble carbohydrates(TSC)in mature leaves also decreased under ED.However,the percentage of the daily C fixation reserved in mature leaves increased.These transient C pools were largely composed of TSC and were mainly used for consumption by increased nocturnal respiration rather than for transport.As the days went on,both the amount of C accumulated and the percentage of the daily fixed C that was reserved in leaves decreased,which could be largely accounted for by the attenuated starch synthesis in all treatments.The activities of ADPglucose pyrophosphorylase and soluble starch synthase decreased significantly over time.Therefore,this study concluded that both starch and TSC are involved in the coordination of the C supply and plant growth under a sudden C shortage but that they may be involved in different ways.While the ratio of reserved C to daily fixed C increased to maintain blade function under acute C starvation,both the amount and the proportion of C reserved in mature leaves decreased as plant growth continued in order to meet the growth demands of the plant.

内生Bacillus svelezensis HBB5菌株发酵盾叶薯蓣产薯蓣皂苷元的研究

目的探讨内生Bacillus svelezensis HBB5菌株发酵宿主植物盾叶薯蓣产薯蓣皂苷元的能力。方法接种内生B.svelezensis HBB5及B.subtilis ATCC 6633菌株(0.35×10^(8) CFU/mL)至含盾叶薯蓣地下茎组织的液体培养基,32℃、165~185 r/min连续发酵108 h,检测发酵液细菌、pH、淀粉、麦芽糖、葡萄糖、淀粉酶(α-amylase)及薯蓣皂苷元溶出率等指标。结果内生B.svelezensis HBB5菌株有较强的酸、碱耐受力[pH(4.8±0.2)~(8.4±0.2)],相比B.subtilis ATCC 6633[pH(5.2±0.2)~(8.7±0.2)]差异不明显;前者达峰值生长量(60×10^(8±2) CFU/mL)明显高于后者(32×10^(8±2) CFU/mL)。发酵36~60 h时,B.svelezensis HBB5、B.subtilis ATCC 6633菌株发酵液的淀粉、麦芽糖、葡萄糖浓度达峰值,分别为(37.41±3.12)、(27.83±2.14)ng/mL,(21.06±1.25)、(16.54±1.08)ng/mL,(54.33±3.12)、(36.65±2.10)ng/mL,前者均高于后者。同时,B.svelezensis HBB5菌株维持高的α-amylase酶活性及薯蓣皂苷元溶出率。结论内生B.svelezensis HBB5菌株拥有较强的耐酸碱、降解淀粉、提高薯蓣皂苷元溶出的能力,为工业生产薯蓣皂苷元提供了一个新的方法。