Penicillium urticae Bainier enumeration in soils

Summary A dilution plating method estimatedPenicillium urticae Bainier numbers in soil. This method, which used an agar layering technique and a cyclic incubation of 8 hours at room temperature (about 25°C) and 16 hours at 5°C, permitted the differential growth and sporulation in favor ofP. urticae B. over other common soil fungi.Procedures of extraction, paper chromatography, infrared analysis, and bioassay assayed for accumulated patulin. A combination of these methods routinely estimatedP. urticae B. numbers in soils and authenticated patulin production by selected isolates.Contribution from the Northern Plains Branch, Soil and Water Conservation Research Division, Agricultural Research Service, USDA, in cooperation with the Nebraska Agricultural Experiment Station, Lincoln. Published as Paper No. 2275, Journal Series, Nebraska Agricultural Experiment Station.Soil Scientist, USDA, Grand Junction, Colorado (formerly Chemist, USDA, Lincoln, Nebraska); and Microbiologist, USDA, Lincoln, Nebraska, respectively.     

The inhibition of seedling growth by crop residues in soil inoculated withPenicillium urticae Bainer

Summary Laboratory experiments were conducted to determine the effects of crop residues, without and withPenicillium urticae Bainer inoculation, on growth of wheat seedlings in soil. Fifty grams of Sharpsburg silty clay loam soil, containing 1% by weight of incorporated alfalfa, sorghum and corn stover residue, were placed in petri dishes, autoclaved, wetted to 40% moisture, and incubated at 24°C. for periods of 2, 3, and 4 weeks. One-half of the petri dishes were inoculated withP. urticae. Germination and seedling-shoot measurements were taken after 7 days of growth.The results of this study showed that (1) inoculation of soil generally reduced seedling height regardless of the residue treatment; (2) inoculation of soil containing corn and sorghum residues resulted in greater tissue production but reduced height of seedlings as compared to non-inoculated soils; and (3) in the absence of residues, the inoculated control soils were a better growth medium for wheat seedlings than were the non-inoculated control soils. In addition, alfalfa residues, especially in the presence ofP. urticae, were strongly inhibitory to the wheat seedlings, causing curling and reduced wheat-seedling root growth.Joint contribution from University of Nebraska and Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, and Nebraska Agricultural Experiment Station, Lincoln, Nebraska, cooperating. Published with the approval of the Director as Paper No. 1242, Journal Series, Nebraska Agricultural Experiment Station.     

Copper as essential to wheat reproduction

Summary The role of Cu in promoting the reproductive phase of growth was examined using Thatcher spring wheat (Triticum aestivum L.). Plants were grown in limed Bladen soil (pH 5.3) in a controlled growth room. The plants were first harvested when five leaves had developed (day 23) and some top leaves of Cu-deficient (-Cu) plants had rolled (withertip) indicating a Cu deficiency. The leaves were shorter on Cu than Cu-sufficient (+Cu) plants, and fewer leaves developed. As they entered the reproductive growth phase, +Cu plants accumulated reducing sugars and reduced 2, 3, 5- triphenyltetrazolium chloride (TTC) in their stems, while Cu plants had lower concentration of the reducing sugars and very little TTC was reduced indicating a reduction in energy and in reducing capacity. Thin-layer-chromatography showed that top leaves of Cu plants contained higher concentrations of aspartic acid, alanine, and serine; and less aminobutyric acid than +Cu plants. Nitrate, P, and K concentrations were higher, and Ca and Cu were lower in Cu than in +Cu plants.Contribution of U.S. Department of Agriculture, Agricultural Research Service, Plant Stress Laboratory, Northeast Region, Beltsville, MD 20705 and North Central Region, Department of Agronomy, University of Nebraska, Lincoln, NE 68583 as Paper No.5187, Journal Series, Nebraska Agricultural Experiment Station.Contribution of U.S. Department of Agriculture, Agricultural Research Service, Plant Stress Laboratory, Northeast Region, Beltsville, MD 20705 and North Central Region, Department of Agronomy, University of Nebraska, Lincoln, NE 68583 as Paper No.5187, Journal Series, Nebraska Agricultural Experiment Station.     

Tissue analyses guidelines for diagnosing sulfur deficiency in white wheat

Summary Visual identification of S deficiency in white wheat is difficult since deficiency symptoms are nearly identical with those of N deficiency. In this study, S deficiency was best identified by determining the total N/S ratio rather than S concentration in vegetative tissue. Vegetative growth generally decreased from tillering to boot when the whole plant N/S ratio exceeded 17. The N/S ratio in S-sufficient plants declined gradually with age, implying that the critical N/S ratio may decline with advancing growth. Changes in stem: leaf ratio could have been responsible for the decline since the N/S ratio in stem tissue at heading was less than that of green leaf tissue.Sulphur concentration less reliably indicated S-deficiency, because differences in S levels between S-deficient and S-sufficient wheat, were often less than year-to-year variation of S concentration of plants sampled at the same growth stage. In addition, S concentration in whole plants declined sharply between tillering and heading. These factors make it difficult to designate a critical S level. Sulfur distribution among various plant organs suggests that critical S levels might best be obtained by utilizing green leaf tissue.Nitrogen concentration in S-sufficient wheat plants also decreased quite rapidly with growth, which indicates a similar difficulty for determining critical N percentages. Consequently, the most reliable distinction between N and S deficiency in wheat was accomplished by evaluation of the total N/S ratio in whole plant tissue.Contribution from the Agricultural Research Service, USDA, in cooperation with the Agricultural Experiment Station, Oregon State University. Technical Paper No.3953 of the latter.     

稻-麦轮作系统土壤水解酶及氧化还原酶活性对开放式空气CO2浓度增高的响应

研究了FACE条件下(CO2浓度增加200μmol·mol^-1)水稻、小麦不同生育期0～10cm土层土壤脲酶、磷酸酶、芳基硫酸酯酶、脱氢酶活性的变化．结果表明,FACE条件下,土壤脲酶活性在冬小麦生育前期低于对照,在孕穗期高于对照;在水稻生育前期高于对照,在成熟期低于对照．磷酸单酯酶活性在冬小麦生育期高于对照;在水稻分蘖期高于对照,在生育后期(拔节期、抽穗期和成熟期)低于对照．芳基硫酸酯酶活性在小麦越冬期和孕穗期低于对照,在分蘖期和成熟期高于对照;在水稻生育期间均高于对照．脱氢酶活性在小麦和水稻的生育前期低于对照,在后期高于对照．     

Influence of Temperature on the Virulence of Two Races of Meloidogyne chitwoodi on Wheat and Barley

Races of the Columbia root-knot nematode, Meloidogyne chitzooodi, from Idaho (R1) and Utah (R2) suppressed (P < 0.05) tillering of Dusty winter wheat, Fielder spring wheat, Luther winter barley, and Steptoe spring barley at 15-30 C. Nematode inoculum density was negatively correlated with tillering (r = -0.79). Inoculum densities of both nematode races were negatively correlated with heads per plant (r = -0.83), head length (r = -0.87), and head dry weight (r = 0.73) of Fielder spring wheat and Steptoe spring barley at all temperatures; the greatest growth restrictions occurred at Pi 20 eggs/cm³ soil. Both nematode races were most damaging at 25-30 C. Fielder spring wheat and Steptoe spring barley inoculated with R2 produced fewer heads than R1 when inoculated at 15 C, whereas the same cultivars inoculated with R1 produced fewer heads than R2 at 30 C. No differences were observed between root growth of winter and spring wheat or between winter and spring barley. Nematode reproduction was positively correlated to temperature (r = 0.87) and negatively correlated with inoculum density (r = -0.86). Reproductive rates were greatest with Pi = 2 eggs/cm³ soil at 25 C and lowest with Pi = 20 eggs/cm³ soil at 15 C for both nematode races.     

Effect of long-term application of manure and fertilizer on biological and biochemical activities in soil during crop development stages

A field experiment was conducted to investigate the effect of six long-term (34-year) fertilizer and farmyard manure (FYM) treatments (Control, N, NP, NPK, NPK+S, NPK+FYM) and three physiological stages of wheat growth on the microbial biomass carbon (MBC), nitrogen (MBN) and dehydrogenase, mineralizable N and phosphatase activities in soil. It was found that a balanced application of NPK+FYM gave the highest values for the measured parameters and lowest at the control. Values were generally highest at tillering, followed by the flowering and dough stages. A significant positive interaction between fertilizer treatments and physiological stages of wheat growth was observed, being highest at maximum tillering due to application of NPK+FYM. Stepwise regressions have revealed that grain yield of wheat was significantly associated with mineralizable N at tillering (R(2)=0.80), MBC at flowering (R(2)=0.90) and alkaline phosphatase activity (R(2)=0.70) at dough stages of wheat growth.     

Mitochondrial DNA synthesis during fungal spore germination

Summary Germinating spores of the fungus Botryodiplodia theobromae incorporated guanine-8-C¹⁴ into both the nuclear DNA and mitochondrial DNA fractions. Ethidium bromide inhibited the synthesis of mitochondrial DNA without having a significant effect on nuclear DNA synthesis or on the rate and extent of spore germination. Rates of leucine and uracil incorporation and of oxygen uptake were not significantly affected by ethidium bromide until germination was nearly completed. Mitochondrial DNA synthesis is apparently not required for germination of the spores of B. theobromae but is probably essential to continued vegetative growth.Abbreviations DNA deoxyribonucleic acid - mit-DNA mitochondrial DNA - nuc-DNA nuclear DNA - RNA ribonucleic acid - EB ethidium bromide - Tris tris (hydroxymethyl)aminomethane Published with the approval of the Director as Paper No. 3331, Journal Series, Nebraska Agricultural Experiment Station. Research reported was conducted under Project No. 21-17. Paper No. 7877, Scientific Journal Series, Minnesota Agricultural Experiment Station.     

Emergence and growth of two non-nodulated soybean genotypes (Glycine max (L.) Merr.) in response to soil acidity

Toxic levels of extractable soil Al limit production of important crops in many areas of the world. The nature of the limitation in soybeans is not completely understood. Our objectives were to investigate the cause of acid-soil-induced delays in seedling emergence, the effect of acidity on productivity in non-nodulated soybeans and further test the Al tolerance of PI 416,937 compared to a sensitive control, Essex. Growth characteristics of the two genotypes through the flowering stage were measured on a Corozal clay (Aquic Tropudult) in Puerto Rico which had been differentially limed to provide a wide range of soil Al. Early growth was also studied in the laboratory using soil from the field experiment. Highly acidic soil conditions, coupled with high Al levels, reduced growth in both Essex and PI 416,937. The principal factor responsible for delayed emergence in the high Al soil was not delayed radicle initiation, but delayed initiation of hypocotyl elongation. Hypocotyl initiation was highly associated with rate of tap root growth, with the former possibly determined by the latter, because a minimum tap root length of 60 mm was required in both high and low Al soils before hypocotyl initiation commenced. In seedlings, the high acidity reduced root more than shoot growth. By 44 days after planting (DAP), however, soil acidity had reduced shoot growth greatly. Although the soybean plants were not nodulated, foliar N levels and shoot growth were decreased by high Al levels, indicating that interference with N fixation may not be the sole mechanism by which nitrogen accumulation and plant growth is reduced in the field.Joint contribution from the USDA, ARS, Tropical Agriculture Research Station, Mayaguez, PR; USDA, ARS, Soybean and Nitrogen Fixation Research Unit, Raleigh, NC, and the Agricultural Experiment Station-University of Puerto Rico (AES-UPR), Rio Piedras, PR.Joint contribution from the USDA, ARS, Tropical Agriculture Research Station, Mayaguez, PR; USDA, ARS, Soybean and Nitrogen Fixation Research Unit, Raleigh, NC, and the Agricultural Experiment Station-University of Puerto Rico (AES-UPR), Rio Piedras, PR.     

Soybean root respiration assessed from short-term14C-activity changes

During and immediately after labelling of soybeans (Glycine max. L.) in the field by exposure to¹⁴CO₂, its respiratory deposit into the soil atmosphere, and its liberation from the soil were used in conjunction with estimates of below-ground plant biomass to apportion total soil respiration. Root respiration of soybean plants at stage V₆ was estimated at 4 mg CO₂.(g root)^–1.h^–1. Soil biota, during the same time, contributed 35% of total soil respiration.Contribution from the Missouri Agricultural Experiment Station. Journal Series Number 10700. Funded in part by USDA Grant SE 83-CRSR-2-2309.     

Growth and patulin formation byPenicillium urticae Bainier in pure and mixed cultures

Penicillium urticae Bainier synthesized patulin in potato-dextrose medium at temperatures ranging from 5 to 30°C. Maximum patulin yield was 2700 μg/ml of culture fluid in 14 days at 25°C. Two distinctive intervals affected patulin formation: 15 to 20°C and 30 to 35°C, the former favorable and the latter detrimental. An incubation period of 11 to 14 days made a nonsterile mixture of weathered wheat straw and soil a favorable medium for patulin formation. Autoclaved weathered wheat straw, inoculated withP. urticae alone, or in combination withTrichoderma sp., was a medium comparable to nonsterile, incubated weathered wheat straw in soil. Both carbon source and accessory growth factors were important for patulin formation. Of seven media tested, potato-dextrose was superior to potatodextrose supplemented with 70 ppm Zn-ions and 16 ppm Fe-ions, potatosucrose, Raulin-Thom, autoclaved weathered wheat straw in pure culture, weathered wheat straw in nonsterile soil, and autoclaved weathered wheat straw in mixed culture, in that order. Patulin production ranged from 337.5 to 0.2 mg/g of C in the medium. Contribution from the Northern Plains Branch, Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, in cooperation with the Nebraska Agricultural Experiment Station, Lincoln. Published as Paper No.2621, Journal Series, Nebraska Agricultural Experiment Station.     

华北高产农田生态系统中冬小麦分蘖期生长与碳截留

模拟华北高产施肥条件盆栽冬小麦,采用^14C同位素对分蘖期冬小麦进行脉冲标记,并分别在分蘖期、拔节期、花期和成熟期取样测定冬小麦地上部、根和土壤中的^14C含量,研究冬小麦光合固定碳对土壤碳库的输入机制。结果表明：冬小麦冬前植株地上部分的生长可以用三次方程较好地拟合;冬小麦出苗后36d停止生长,植株地上部分平均干质量为0．219g·株^-1,折合为0．09gC·株^-1。冬小麦分蘖期光合固定的碳在植株地上部分、地下根部和土壤中的分配比例分别占光合同化HC总量的35.2％、10．4％和51．3％。到冬小麦生长期末,植株地上部分、地下根部和土壤中的^14C含量分别降至最初光合同化^14C总量的3．9％、4．6％和26．4％。通过呼吸作用所释放的^14C总量随作物生长时间的推移不断增大,到生长期末,通过呼吸作用输出的^14C的量占分蘖期冬小麦固定总量的65．2％。     

低磷和干旱胁迫对小麦生长发育影响的研究初探

研究了低磷和干旱胁迫对小麦（Triticum aestivum L.）生长发育的影响。结果表明,低磷胁迫能显著降低小麦的分蘖数、叶片相对含水量和叶绿素含量,进而抑制小麦的生长发育,降低其生物产量和经济产量,不耐低磷品种中国春受影响的程度要大于耐低磷品种烟中144。在相同条件下,干旱能够强化磷胁迫效应,表现出明显的胁迫叠加现象。     

Characteristics of ribonucleic acids isolated from Botryodiplodia theobromae pycnidiospores

Nucleic acids isolated from dormant and germinated Botryodiplodia theobromae pycnidiospores contain five distinct species of RNA. They include two ribosomal species, two ribosomal-associated species and transfer RNAs. Sedimentation coefficients of 25.1S and 18S were obtained for the two ribosomal RNA species and 5.8S and 5S for the two ribosomal-associated RNA components. Molecular weights of 1.20, 0.67, 0.054 and 0.035x10⁶ daltons were obtained after formaldehyde treatment and electrophoresis on polyacrylamide gels for these same four RNAs. Methylated nucleotides were present in the transfer RNAs and large and small ribosomal RNAs; in contrast 5.8S and 5S RNAs contained few methylated nucleotides. In addition to the 5 distinct RNA species, polyadenylate-containing RNA was isolated from both dormant and germinated spores.Published with the approval of the Director as paper no. 5006, Journal Series, Nebraska Agricultural Experiment Station. The work was conducted under Nebraska Agricultural Experiment Station Project no. 21-17.     

华北平原冬小麦农田生态系统CO_2通量特征及其影响因素

利用2014—2015年中国科学院封丘农业生态实验站涡度相关系统观测的冬小麦农田生态系统CO_2通量数据,结合试验地常规气象观测系统的气象数据,分析冬小麦4个生育期(分蘖期、越冬期、拔节期和灌浆期)内CO_2通量的日变化,研究净生态系统碳交换(NEE)的季节变化及其与气象要素的关系.结果表明:冬小麦整个生育期内NEE为-360.15g C·m^-2,总初级生产力总量为1920.01 g C·m^-2,冬小麦农田生态系统具有较强的固碳能力.冬小麦农田生态系统CO_2通量具有明显的日变化和季节变化特征,分蘖期表现为碳源,越冬期、拔节期和灌浆期表现为碳汇.表观初始光能利用率平均值为0.03 mg CO_2·μmol^-1,光饱和时的生态系统生产量平均值为1.53 mg CO_2·m^-2·s^-1,月平均生态系统呼吸为193.92g C·m^-2·month^-1.冬小麦农田生态系统4个生育期NEE与光合有效辐射的相关关系均达到极显著水平.分蘖期、拔节期和灌浆期NEE与饱和水汽压差的相关关系极显著,越冬期达显著水平.冬小麦分蘖期、越冬期和灌浆期NEE日总量与土壤温度呈正相关,拔节期呈负相关关系.     

华北平原冬小麦农田生态系统CO2通量特征及其影响因素

利用2014—2015年中国科学院封丘农业生态实验站涡度相关系统观测的冬小麦农田生态系统CO₂通量数据,结合试验地常规气象观测系统的气象数据,分析冬小麦4个生育期(分蘖期、越冬期、拔节期和灌浆期)内CO₂通量的日变化,研究净生态系统碳交换(NEE)的季节变化及其与气象要素的关系.结果表明: 冬小麦整个生育期内NEE为-360.15 g C·m^-2,总初级生产力总量为1920.01 g C·m^-2,冬小麦农田生态系统具有较强的固碳能力.冬小麦农田生态系统CO₂通量具有明显的日变化和季节变化特征,分蘖期表现为碳源,越冬期、拔节期和灌浆期表现为碳汇.表观初始光能利用率平均值为0.03 mg CO₂·μmol^-1,光饱和时的生态系统生产量平均值为1.53 mg CO₂·m^-2·s^-1,月平均生态系统呼吸为193.92 g C·m^-2·month^-1.冬小麦农田生态系统4个生育期NEE与光合有效辐射的相关关系均达到极显著水平.分蘖期、拔节期和灌浆期NEE与饱和水汽压差的相关关系极显著,越冬期达显著水平.冬小麦分蘖期、越冬期和灌浆期NEE日总量与土壤温度呈正相关,拔节期呈负相关关系.     

Carbohydrate metabolism of lactic acid cultures IV. Glycolytic and HMS pathway enzymes inStreptococcus lactis and their sensitivity to antibiotics

Streptococcus lactis possessed glucose-6-phosphate-dehydrogenase, 6-phosphogluconic-dehydrogenase, ribose-5-phosphate isomerase and transketolase enzyme activities. The presence of the previously reported aldolase, lactic dehydrogenase, alcohol dehydrogenase and aldehyde dehydrogenase activities in the organism was confirmed. These results indicated that carbohydrate metabolism in the organism follows both Embden-Meyerhof-Parnas and Hexose monophosphate shunt pathways. The presence of aldolase, glucose-6-phosphate-dehydrogenase and 6-phosphogluconic-dehydrogenase is in accordance with the fact that the organism is a facultative homofermenter.Antibiotics suppressed or retarded the activities of the above enzymes to different degrees and induced alterations in the glycolytic and alternate pathways of carbohydrate metabolism ofS.lactis.This work was supported in part by U.S. Public Health Service Research Grant E-2486, from the National Institute of Health. It is being published with the approval of the Director as paper No. 2528, Journal Series, Nebraska Agricultural Experiment Station, Lincoln.Able technical assistance of Miss Clara Zoz is gratefully acknowledged.     

Development of detached wheat spikelets in culture

A liquid culture medium in cluster culture dishes supported development of detached wheat spikelets from 7 days pre-anthesis to grain maturity. Development of florets in vitro closely resembled that in vivo as revealed by the growth of anthers, ovaries, and the viability of developing embryos. The number and viability of pollen produced and percentage seed set, however, were significantly lower in cultured spikelets. The developing grain was grown to maturity in vitro by transfering the spikelets into fresh liquid medium every two weeks. The culture of wheat spikelets represents a new experimental tool for studying developmental phenomena and host-pathogen interactions in wheat.The research was supported by the Agricultural Research Service, US Department of Agriculture, in cooperation with the Agricultural Experiment Station, Oregon State University; Technical Paper No 8638 of the latter. Mention of a commercial product does not represent an endorsement of the product by the USDA or imply approval to the exclusion of other comparable products.     

Photosynthesis and growth of winter wheat in response to waterlogging at different growth stages

A study on photosynthetic and yield effects of waterlogging of winter wheat at four stages of growth was conducted in specially designed experimental tanks during the 2007–2008 and 2008–2009 seasons. Compared with the control, waterlogging treatments at tillering and jointing-booting stages reduced photosynthetic rate (P _N) and transpiration (E) significantly, it also decreased average leaf water-use efficiency (WUE, defined as the ratio of P _N to E) by 3.3% and 3.4% in both years. All parameters returned quickly to the control level after soil was drained. Damage to the photosynthetic apparatus during waterlogging resulted in a lower F_v/F_m ratio, especially at the first two stages. A strong reduction in root length, root mass, root/shoot ratio, total dry mass, and leaf area index were observed. The responses from vegetative plants at tillering and jointing-booting stages were greater than in generative plants at onset of flowering and at milky stages. The number of panicles per hectare at tillering stage and the spikelet per panicle at the stages of jointing-booting and at onset of flowering were also significantly reduced by waterlogging, giving 8.2–11.3% decrease of the grain yield relative to the control in both years. No significant difference in yield components and a grain yield was observed between the control and treatments applied at milky stages. These responses, modulated by the environmental conditions prevailing during and after waterlogging, included negative effects on the growth, photosynthetic apparatus, and the grain yield in winter wheat, but the effect was strongly stage-dependent.     

Effects of Patulin and Method of Application on Growth Stages of Wheat

When a single, 100-mug/ml application of patulin, produced by Penicillium urticae Bainier, was applied to growth stages 7, 9, 10, and 10.1 (Feekes scale) of Lee spring wheat (Triticum aestivum L.), decreases in internodal elongation, floret number, seed weight, and seed number were observed. Yields were reduced according to the proximity of application prior to heading. Application of patulin to the soil in crystalline form and dissolved in aqueous solution were also investigated, and the solution method of application was found to be the treatment of choice. A single exposure of growing wheat plants to patulin can produce yield reductions similar to those observed in stubble-mulch farming.