作物品种和化学固定剂对玉米谷物中镉和锌积累的影响

A field experiment was conducted to investigate the effects of soil amendments(lime,nano-Si foliar solution and used diatomite) on the growth and metal uptake of three maize(Zea mays L.) cultivars grown in a Cd and Zn-contaminated acidic soil.The addition of lime significantly increased the maize grain yields and decreased the concentrations of Zn and Cd in the grains and shoots of maize when compared with the control.Among the three maize cultivars,Yunshi-5 accumulated the lowest amounts of Cd and Zn in the grain.The concentrations of Zn and Cd in the grain of Yunshi-5 conformed to the Chinese feed standards.These data revealed that a combination of low metal-accumulating maize and chemical fixation could effectively provide a barrier to prevent metals from entering the human food chain.     

正交设计优化玉米SSR—PCR反应体系的研究

为建立适宜玉米SSR—PCR的反应体系和扩增程序,利用正交设计L16（4^5）表,对反应体系的模板DNA、dNTPs、Primers、Taq DNA聚合酶的浓度进行4因素4水平优化筛选和扩增程序的优化,确立了最优反应体系和扩增程序。即在10μL体系中,模板DNA20ng,1×PCR buffer,dNTPs62．5pmol／μL,Primers0．25pmol／μL,Taq DNA polymerase0．5U。反应程序为：94℃预变性5min;94℃变性45S,60℃退火45S,72℃延伸1min,32个循环;72℃延伸5min,4℃保存。使用300对SSR引物对重组近交系的两亲本扩增,筛选出条带清晰,有差异的引物94对,用于基因连锁图谱构建和QTL定位。     

Corn forage yield and chemical composition as influenced by sulfur fertilization

Abstract

Soil sulfur (S) deficiency for plant growth has become an increasing problem in the United States. A field experiment was conducted to investigate effects of fertilization with 0 and 67 kg S/ha as a single or split application, in a Latin square design, on corn (Zea mays L.) forage yield and chemical composition. Sulfur fertilization by either method increased yield of whole plant and grain 7% and increased number of plants with two ears. Total S and sulfate‐S concentration in whole corn plants, leaf, stem, and grain were increased with S fertilization. The nitrogen (N):SO₄‐S ratio was a useful indicator of S deficiency.     

Nitrogen use efficiency and nutrient partitioning in maize as affected by blends of controlled-release and conventional urea

ABSTRACT

Blends of controlled-release urea (CRU) and conventional urea can be an alternative to conventional fertilization to improve nitrogen use efficiency (NUE) and reduce costs when applied as a single application to agricultural crops. Different indexes of NUE, grain yield, nutrient uptake and partitioning in maize (Zea mays L.) were investigated in field experiments. The treatments consisted of a single rate of 180 kg N ha^?1 with different proportions of polymer-sulfur coated urea (PSCU) and conventional urea (U) applied incorporated at sowing (0.05 m below and 0.1 m to the side of the seed row) at two tropical sites (Site 1, Typic Haplustox; Site 2, Rhodic Haplustox) in Brazil. A control treatment (without urea-N) and a treatment with conventional urea management (UCM: 20% of urea-N applied as basal fertilizer and 80% of N applied as top dressing) were also included. This study demonstrates that blends of PSCU and U are efficient in supplying N throughout the maize cycle at a Typic Haplustox site when applied in a single application incorporated at sowing, resulting in high yields and adequate macronutrient uptake. PSCU improved NUE index compared to U and UCM. There was not response for N fertilization in the Rhodic Haplustox site.     

Changes in Anthocyanin Content as Indicator of Maize Sensitivity to Selenium

The aim of this experiment was to examine the effect of exogenous selenium (Se) on anthocyanin and chlorophyll accumulation, Se content, as well as the growth of maize (Zea mays var. ‘saccharata Kcke’) cv. ‘Zlota Karlowa’ seedlings. Plants were grown hydroponically in Hoagland's nutrient solution at different pH values: 4.5, 6.2, and 7.5. Selenium was added to the solution as either selenate (Na₂SeO₄) or selenomethionine (C₅H₁₁NO₂Se) to a final concentration of: 0 (control), 5, 25, 50, and 100 μ M Se. Generally, the presence of Se in the medium caused an increase in the anthocyanin content and a simultaneous decrease of the total chlorophyll concentration depending on the Se form and dosage. Higher concentrations of anthocyanin were detected in the presence of selenomethionine than selenate, notably at pH 4.5. The effect of individual Se forms on maize seedlings, expressed on the basis of the fresh weight, indicate that selenomethionine was more phytotoxic than selenate. Selenium content both in roots and shoots increased linearly with increasing Se concentration in solution culture. However, a much higher Se level was found in the maize organs when plants were supplied with selenomethionine than selenate. Experimental evidence shows that the changes in anthocyanin content can be used as a test parameter reflecting the degree of Se toxicity in maize plants, and may be potential useful for bioindication of Se phytotoxicity in other higher plants.     

The nitrogen content of corn grain as affected by hybrid,population, and location

Abstract

Samples were taken from 9 of the 20 major experiments which comprised the Illinois commercial corn (Zea mays L.) performance trial and evaluated for grain yield, percent grain N, and grain N yield.

The mean percent N in the grain was 1.54%, with 91.8% of the samples between 1.34 to 1.74%. Although location and plant population affected the mean values, the range of values about the mean was relatively unaffected. Grain N yield was more closely correlated with grain yield than with percent grain N.     

Placement Effect of Controlled-release and Conventional Urea Blend in Maize

ABSTRACT

A single application of polymer-sulfur coated urea (PSCU) and conventional urea (U) blends can supply nitrogen (N) throughout the maize (Zea mays L.) cycle but it could become harmful for plants if not properly placed in the soil due to a possible salt stress which would reduce dry weight (DW) and N uptake (NU) in maize. DW and NU in maize plant as well as soil pH and electrical conductive (EC) were evaluated in a greenhouse pot trial. Treatments consisted of different placements (0.05, 0.1 and 0.15 m below and 0, 0.05 and 0.1 m to the side of seed row) of fertilizers (70%PSCU + 30%U, and 100%U) applied at maize sowing in band at a rate equivalent to 180 kg N ha^?1 in a Rhodic Eutrustox soil. Control treatment (without N) was also included. At V7 (vegetative leaf stage 7), N fertilizers placed 0.15 m below of seed row provided higher total DW, total NU, EC and pH (in fertilizer row) than 0.05 m and 0.1 m. 70%PSCU + 30%U provided higher total DW and total NU than 100%U in placement 0 m. In addition, 70%PSCU + 30%U placed 0.1 m to the side of seed row provided lower total NU and EC (in fertilizer row) than 0 m. 70%PSCU + 30%U and 100%U placement can negatively interfere maize in vegetative stage when applied incorporated in band at sowing. The proper placement for this condition was 0.15 m below and 0.1 m to the side of seed row.     

N、P、K肥对玉米幼苗吸收和积累重金属的影响

采用室内盆栽试验,研究复合污染土壤中施加氮肥（NH4Cl）、磷肥（Na2HPO4）和钾肥（KCl）对高生物量经济作物玉米（Zeamays L.）幼苗生长以及吸收和积累重金属的影响。结果表明,不同施肥方式和浓度处理对玉米生物量变化以及吸收重金属有不同影响,NH4Cl能显著提高玉米地上部生物量、土壤Pb、Cd有效态含量,增加玉米对重金属Pb、Cd、As的提取量,最大分别可提高1.7、2.0倍和1.2倍。不同施肥方式和处理浓度均显著影响土壤有效态Pb含量,Na2HPO4在中浓度处理时显著降低土壤Pb的有效性,高浓度时则显著增加土壤有效态As含量,使玉米地上部对As的积累量有明显提高。在不同的浓度水平下,钾肥处理使玉米提取Pb含量显著高于氮肥和磷肥,其中低浓度KCl处理使玉米提取Pb量比对照增加2.4倍。对Pb-Cd-As复合污染农田土壤来说,施用氮肥（NH4Cl）处理对强化玉米的修复效果最好。     

Growth and Zinc Uptake and Use Efficiency in Food Crops

Zinc (Zn) deficiency in annual crops is very common in Brazilian Oxisols. Data are limited on Zn uptake and use efficiency during crop growth cycles. A field experiment was conducted during two consecutive years with the objective to determine shoot dry weight and Zn uptake and use efficiency in upland rice, dry bean, corn, and soybean during growth cycles. Shoot dry weight of four crops was significantly increased in an exponential quadratic fashion with increasing plant age. Rice and corn had higher shoot dry weights and grain yields than dry bean and soybean. Zinc concentration in rice and corn decreased in a quadratic fashion with increasing plant age. However, in dry bean and soybean, Zn concentration had a quadratic increase. Zinc uptake followed an exponential quadratic response in four crops, and it was higher in corn and upland rice than in dry bean and soybean. Zinc use efficiency in shoot dry‐weight production had significant quadratic responses in upland rice and soybean with increasing plant age. In corn, Zn use efficiency for shoot dry‐weight production was linear as a function of plant age. Zinc use efficiency for grain production was maximum for corn and minimum for soybean. Hence, cereals had higher Zn use efficiency than legumes.

Zinc concentration in grain of dry bean and soybean was higher than in upland rice and corn, which is a desirable quality factor for human consumption so as to avoid Zn deficiency.     

Effects of Soil Fertility Management on Growth,Yield, and Water-Use Efficiency of Maize (Zea mays L.) and Selected Soil Properties

Maize was grown for two cropping years to investigate the supplementary effect of inorganic fertilizer with cow dung on growth, yield, water-use efficiency, and soil properties. Five treatments were imposed: unfertilized control and four different fertilization packages comprising two different levels of inorganic fertilization with cow dung as supplements, sole inorganic fertilizer, and sole cow dung. Results analyzed after the two cropping years showed significant differences in growth and yield. A reduction in yield was observed for the unfertilized plots, whereas yields in the plots of supplemented inorganic fertilizer with cow dung increased and were significantly at par with the sole inorganic fertilizer plot. Water-use efficiency was improved for the fertilized plots. Significant improvement was observed in the water-stable aggregates with plots that received cow dung as organic manure either in part with inorganic fertilizer or as sole cow dung.     

玉米基因组Fosmid文库构建及类受体激酶基因(Psy1和Psy2)筛选

玉米(Zea mays L.)病害的发生和流行是限制玉米高产稳产的重要因素。玉米细菌性褐斑病是目前具有潜在危害性的病害之一,在抗性基因遗传规律和染色体定位研究方面取得一定进展,但在基因克隆、功能鉴定等研究上进展较为缓慢,利用构建的Fosmid文库克隆抗病候选基因是目前较为快捷和有效的方法之一。本研究以玉米细菌性褐斑病的抗病自交系F349为材料构建了玉米Fosmid文库,克隆总数约为3.7×105个,平均插入片段长度为32 kb,实现4.73倍的玉米基因组覆盖,筛选到任意基因或序列的概率达到了99.12%。基于该文库,利用不同引物组合进行了两个类受体蛋白激酶基因(Psy1和Psy2)的克隆筛选,得到14个阳性克隆,其中4个阳性克隆包含Psy2基因和Psy1基因部分片段;3个阳性克隆包含完整Psy1基因;对其中两个阳性克隆13-12F-23和32-4A-6的测序结果显示,Psy1基因的启动子和内含子分别被插入了10.0和13.5 kb的外源片段;13.5 kb的插入片段是LTR家族的huck反转录转座子,10.0 kb的插入片段是含有helitron转座元件的复杂转座子;扩增到了Psy1基因的cDNA全长,说明这两种类型反转录转座子的插入并未使基因失活。本研究为玉米基因的克隆和功能分析提供了一种可行的研究途径。     

Impact of Fertilization and Irrigation on the Correlation between the Soil Plant Analysis Development Value and Yield of Maize

The degree of nitrogen (N) supply in maize under nonirrigated and irrigated conditions was measured using a Soil Plant Analysis Development (SPAD) 502 portable chlorophyll meter for 4 years. The lowest readings were obtained from a plot that has not been fertilized for 23 years. The highest SPAD value in the nonirrigated treatments was obtained in 2004, whereas the lowest was measured in the drought year of 2007. In the irrigated treatments, there was a closer correlation between fertilization and SPAD values during the examined 4 years. As the result of fertilization, the average increase of SPAD values in the irrigated plots was greater than in the nonirrigated plots. The result of irrigation on SPAD values was significant every year (P < 0.001), with the largest increase in the drought year of 2003. In the nonirrigated treatments, fertilization and grain yield had a weak correlation, whereas in the irrigated treatments the correlation between the two variables was strong.     

Effect of Elevated [CO2] on Assimilation,Allocation of Nitrogen and Phosphorus by Maize (Zea Mays L.)

To estimate the effect of elevated [CO₂] on nitrogen (N) and phosphorus (P) dynamics and productivity in summer maize, a field experiment was conducted in open-top chambers (OTCs) at different [CO₂] (550 μmol/mol, T1; 750 μmol/mol, T2 and a control, CK) in Nanjing in Jiangsu Province, China. The results showed that maize total N and P accumulation were 13.23–66.56% higher in the elevated [CO₂] treatments than in the CK plots during the jointing, anthesis and maturity stages. There was only a significant difference in total N accumulation between the T2 treatment and CK at maturity (P < 0.05). However, rising [CO₂] decreased the N and P concentrations in each biomass fraction. Elevated [CO₂] increased the amounts of N and P translocation, resulting in the contribution of translocated N to grain N. Similarly, rising [CO₂] increased N and P translocation efficiencies, N or P harvest index, and N or P utilization efficiency based on grain yield and N or P utilization efficiencies based on biomass in both growing seasons. In addition, elevated [CO₂] significantly increased aboveground biomass at three stages, including 4.73–12.34% at maturity. The grain yields of summer maize increased by 21.28% and 29.07% in the two elevated [CO₂] plots. Furthermore, spike numbers, kernels per spike and 100-grain weight were increased by elevated [CO₂] treatments. Kernels per spike and grain yield showed obvious differences between elevated [CO₂] treatments and CK (p < 0.05).     

Yield,Quality Components,and Nitrogen Levels of Silage Corn Fertilized with Urea and Zeolite

The zeolite and urea mixture may be use to improve nitrogen (N)–use efficiency of silage corn. The objective of this study was to evaluate dry-matter yield and nutritional levels of N of silage corn fertilized with urea and zeolite mixture. The experimental design was a 2 × 4 × 4 factorial randomized block design with three replications. Treatments included two types of stilbite zeolite (natural and concentrated), four levels of nitrogen (0, 50, 100, and 200 kg ha^?1), and four ratios of zeolite (25%, 50%, and 100% of N level). Treatments were applied 60 days after planting with the topdressing fertilization. The use of concentrated (650 g kg^?1 of stilbite) or natural (470 g kg^?1 of stilbite) zeolite with urea increased silage corn dry-matter production and leaf N concentrations.     

Sources,Rates and Time of Nitrogen Application on Maize Crops under No-Tillage System

Quantitatively, nitrogen (N) is the foremost nutrient for maize crops (Zea mays L.), but the N source to increase the grain productivity still needs more investigation. Thus, the aim of this experiment was to study sources, rates and time of N application on the crop yield and agronomic characteristics of the maize under no-tillage system. The experiment was carried out during two growing seasons on an Oxisol under the factorial 5 × 3 × 3 scheme with five N rates (0, 50, 100, 150, and 200 kg ha^?1) and three sources (ammonium-sulfate-nitrate as inhibitor of the nitrification (ASN+I), ammonium sulfate (AS) and urea); we applied them two times with four replicates: first time at the sowing or later under side dressing when the plants had the six leaves stage. In the first year, the sources of N had no influence on the number of grain line /ear (NGLE), grain number/line (GNL), total number of grain/ear (TNFE), biomass of 100 grain, plant height (PH), height of the first ear insertion (AFEI) and stalk diameter, in contrast with the foliar N content and the crop yield. Early fertilization with N at the sowing time can afford applications as well as the total side dressing. The increase of the rates had positive influence on the N foliar content, plant height and 100 grains biomass. The highest productivities were found with rates above the threshold of 150 kg ha^?1, no matter the sources and the fertilization time.     

Effect of lead treatment on the distribution of essential elements in cucumber

Changes in the fresh and dry weight of leaf blades, petioles, internodes, and their ion concentrations as well as rates of root exudation were investigated in cucumber grown in hydroponic culture and treated with physiological concentrations of lead (Pb). The growth of flowering cucumber supplied with FeCl₃ shows a typical bell‐shaped curve derived from leaf dry weights, where the 4th, 5th, and 6th leaves are the largest ones. Lead inhibited growth up to 20% (except the youngest leaves which were stimulated), but did not cause morphological changes. Whereas root growth was also retarded by about 20%, exudation was inhibited to 50%, that is, the root resistance to water transport was increased by Pb. In spite of that the dry matter yield of internodes and petioles hardly reached 10 and 5% of that of leaf blades, respectively, their calcium (Ca), magnesium (Mg), and zinc (Zn) concentrations were almost the same. Similarly, the concentrations of these metals in the specific leaf blades are equal despite their different growth characteristics but the concentration of Mn is independent of the growth of the examined tissues. Lead was the only cation to accumulate in the largest leaves. The inhibitory effect of Pb on ion uptake was proportional to the growth inhibition of the tissues except manganese (Mn), the accumulation of which was stimulated by Pb in all the analyzed tissues and copper (Cu) which increased only in the internodes. We could not explain the extremely different ion distributions observed during the growth of cucumber. However, it is evident that the measurement of ion concentrations at whole shoot level is not enough to characterize ion interactions because only some ions accumulate at the same rate as tissues grow. These ions maintain stable concentration levels in shoot parts whereas others decrease or increase independently from growth.     

玉米Lc基因植物表达载体构建及菊花转化

Lc基因是从玉米中分离得到的与花青素合成相关的调节基因，它在多种植物中的异源表达可以增加花青素的含量。本研究对pBI121载体Gus基因后的终止子进行2次PCR扩增，在原Sac I酶切位点后添加了新的Sac I酶切位点，利用组织化学染色法检测，结果表明改造后的载体上的Gus基因能正常表达，终止子功能正常，载体改造成功。用改造的pBI121N构建了含有Lc基因的植物表达载体pBI121N-Lc，利用农杆菌介导法转化菊花叶盘，获得了19株生根抗性苗。通过提取抗性苗基因组总DNA，PCR扩增Lc基因和CaMv35S启动子获得了11个阳性株系，PCR结果表明Lc基因已经转入菊花中。同时，在己获得的转基因植株中发现7个株系的根系有变红的现象。     

Critical Soil Zinc Deficiency Concentration and Tissue Iron: Zinc Ratio as a Diagnostic Tool for Prediction of Zinc Deficiency in Corn

ABSTRACT

Zinc (Zn) fertilizer application is most economic if based on soil test and plant analysis information. The aim of this study was to determine the soil test [diethylenetrinitrilopentaacetate (DTPA) and ethylenetriaminepentaacetic acid (EDTA) extractable] Zn-critical levels and tissue Fe/Zn ratio for corn (Zea mays L.). A greenhouse experiment with 12 soil series and two Zn fertilizer treatments (0 and 15 mg Zn kg^?1 as zinc sulfate) was conducted. Critical Zn deficiency levels were determined using the Cate-Nelson procedure. Relative corn yield varied from 0.59 to 1.64. Critical deficiency levels based on the Cate-Nelson method were 1.50 and 1.17 mg kg^?1 for DTPA and EDTA-extracted soil Zn, respectively. No accurate critical deficiency level could be established using the shoot Zn concentrations. The critical iron (Fe)/Zn ratio in the corn shoot was 3.9. Values greater than 3.9 indicate hidden Zn deficiency and probable response to applied Zn.     

Container and Installation Time Effects on Soil Moisture,Temperature, and Inorganic Nitrogen Retention for an in situ Nitrogen Mineralization Method

Mineralization contributes significantly to agronomic nitrogen (N) budgets and is difficult to accurately predict. Models for predicting N‐mineralization contributions are needed, and development of these models will require field‐based data. In situ mineralization methods are intended to quantify N mineralization under ambient environmental conditions. This study was conducted to compare soil moisture and temperature in intact soil cores contained in cylinders to those in adjacent bulk soil, compare the effect of two resin‐bag techniques on water content of soil within cylinders, and assess the effect of installation duration on inorganic N retention by resins. The study was conducted at a dryland conventionally tilled corn (Zea mays L.) site and an irrigated no‐tillage corn site in eastern Nebraska. Soil in cylinders was slightly wetter (<0.05 g g^?1) and warmer (<1 °C) than adjacent soil. Soil water content was <80% water‐filled pore space (WFPS) at all sampling times and differed little between the two resin‐bag techniques. Greater soil water content and temperature conditions (though small) observed during most of the study period likely enhanced N mineralization within the cylinder compared to N mineralization in adjacent bulk soil, but the magnitude is likely much less than core‐to‐core variation normally observed in a field. Installing cylinders for more than 60 days resulted in loss of inorganic N from resins. Care is needed during installation to ensure that compaction of soil below the cylinder does not impede water movement through the intact soil core. The in situ method utilizing intact soil cores and resin bags replaced at 28‐ to 40‐day intervals is a viable method for measuring N mineralization.     

Genotypic Difference in Nitrogen Acquisition Ability in Maize Plants Is Related to the Coordination of Leaf and Root Growth

ABSTRACT

The capacity of a plant to take up nitrate is a function of the activity of its nitrate-transporter systems and the size and architecture of its root system. It is unclear which of the two components, root system or nitrate-uptake system, is more important in nitrogen (N) acquisition under nitrogen-sufficiency conditions. Two maize (Zea mays L.) inbred lines (478 and Wu312) grown in nutrient solution in a controlled environment were compared for their N acquisition at 0.1, 0.5, 2.5, 5, and 10 mmol L^?1 nitrate supply. Genotype 478 could take up more N than Wu312 at all nitrate concentrations, though the shoot biomass of the two genotypes was similar. Genotype 478 had a larger leaf area and longer root length. The specific N uptake rate of 478 (μmol N g^?1 root. d^?1) was lower than that of Wu312. In an independent nitrate-depletion experiment, the potential nitrate uptake rate of 478 was also lower than that of Wu312. No genotypic difference was found in photosynthesis rate. It was concluded that the greater N acquisition ability in 478 involves the coordination of leaf and root growth. Vigorous leaf growth caused a large demand for N. This demand was met by the genotype's large root system. Besides providing a strong sink for N uptake, the larger leaf area of 478 might also guarantee the carbohydrate supply necessary for its greater root growth.