砂姜黑土区小麦施用磁性合肥增产效应研究

研究结果表明，砂姜黑土区小麦施用磁性复合肥增产效果显著。其主要表现是促进小麦生长发育，增加有效分蘖，提高亩成穗数，提高千粒重，最高产量施肥量为2502kg/hm^2，经济最佳施肥量为934．5kg/hm^2。磁性复合肥处理产量为最高。比对照增产72．0％，增产2410．5kg/hm^2。比处理等量氮磷肥化肥增产11．4％，增产589．5kg／hm^2。比未磁化肥处理增产10．6％，增产550．5kg/hm^2。     

施用不同缓释肥料对春小麦产量的影响

通过对Triabon和Field两种缓释肥料的试验研究，结果表明：缓释肥料具有良好的养分缓释效果，肥效期均可达到100d，但Triabon缓释效果优于国产的Field。施用缓释肥料Triabon 00 g／hm^2，春小麦单产7083 kg／hm^2，比对照增产42．5％，且穗粒数、千粒重均较对照增加明显，Field次之。施用缓释肥料的籽实、茎叶N、P、K携出量分别比等NPK养分混配肥料S提高了2．4％～14．8％，5．6％～21．2％，8．0％～11．3％。缓释肥料的N利用率达到37．2％～60．9％，P利用率24．7％～40．3％，K利用率71．3％～81．9％，减少了肥料损失。     

硅、镁、硼肥对甘蔗产量和产糖量影响的研究

在硅、镁、硼营养较缺乏的甘蔗田，进行硅肥、镁肥、磷肥的施肥效应试验，结果表明：硅、镁、硼肥及其不同施肥水平对甘蔗的株高、茎径、锤度、产量和产糖量有明显的影响。施用硅肥使甘蔗锤度、产量和理论产糖量分别比对照增加0.42～1．11，11．04～14．96t／hm^2和1．84～2．10t／hm^2；施用镁肥分别比对照增加0.93～1．26，4．02～9．55t／hm^2和0．99～1．53t／hm^2；施用硼肥分别比对照增加0．41～1．20，5．00～10．00t／hm^2和0．80～1．82t／hm^2。     

氮硫单施及配施对大蒜的效应研究

系统研究了氮硫肥对大蒜产量和品质的影响，结果表明，在河南省潮土区大蒜施硫以６０ｋｇ／ｈｍ＾２为宜；施肥基施的综合效应优于追施和底施加追施处理，大蒜施用氮肥，一般蒜头增产１６．４％～３０．２％，蒜苔增产８．３％～２８．４％，大蒜经济合理施肥量范围为１９３．２～３２８．６５ｋｇ／ｈｍ＾２，此时大蒜产量在１７７４０．２ｋｇ／ｈｍ＾２以上，氮硫配施比对照平均增产３８．７％，呈显著的正交互作用，３个试验点的     

杂交油菜施用粉煤灰磁化肥的效应

通过对杂交油菜施用粉煤灰磁化复合肥的试验研究，初步探明了粉煤灰磁化复合肥较同等N，P，K的复混肥，未磁化粉煤灰复合肥及当地群众习惯施肥法有显著的增产效果，试验表明，粉煤灰磁化肥在油菜上一般用量为757．58kg/hm^2左右。粉煤灰磁化肥比对照增产21．9％，比当地农民习惯施肥措施增产10．5％，比等量N，P，K混膈肥增产9．9％，增产180kg/hm^2，比未磁化粉煤灰复混肥增产4．5％，最高产量施用粉煤灰磁化肥为1026．9kg/hm^2，油菜产量为2084．85kg/hm^2；最佳产量施用粉煤灰磁化肥为757．58kg/hm^2，油菜产量为2041．79kg/hm^2。     

酸性黄红壤上施用白云石的作物产量效应和经济效益评价

在皖南酸性红黄壤旱地上进行了为期三年的定位试验，以探讨施用白云石改良土壤的效果。研究结果表明：施用白云石能显著地促进作物的生长发育和提高产量，小麦增产11．6％～13．4％，油菜增产9．4％～27．2％，红豆增产21．9％～49．7％，玉米增产10．9％～44．6％，黄豆增产6．6％～29．8％，其增产后效与使用量成显著正相关。施用白云石粉处理三年六季作物累计增加的纯收入为2511．6～5376．8元／hm^2，产投比为27．9～12．4：1。从作物的产量效应和经济效益评价来看，适宜的白云石粉施用量为1100～1600kg／hm^2。     

钴对冬小麦生理生化性状和产量影响的初步研究

在潮土上采用大田小区进行了钴元素肥效试验。试验结果如下：施用适量的钴可以显著提高旗叶的叶绿素含量、硝酸还原酶活性以及小麦的根系活力；各施钴处理较对照增产7．4％～20．3％，施钴量在0．75kg／hm^2以内，随着施钴量的增加，增产效应提高，当施钴量超过0．75kg／hm^2时，随着施钴量的增加，冬小麦的产量增加，但增产效应下降。经回归分析，小麦产量与施钴量呈抛物线型，回归方程为y=-1263．9x^2 2083．4x 4371．7，相关系数r=0．8910，达到5％显著水平。     

氮、磷和钾营养对新海16长绒棉产量和品质的影响

氮肥、磷肥、钾肥N：P2O5：K2O=1：0．71：0．30并配合Zn、Mn、B微肥施用，经济施肥量为N189．3kg／hm2、P2O5134．4kg／hm^2、K2O57．2kg／hm^2，能显著促进棉花的生长发育和提高产量，比对照增产40％，对新海16纤维品质中的马克隆值影响显著，但对纤维综合品质影响不显著。     

黄泛沙区冬小麦施钾效应研究

研究了施钾对冬小麦的生长及产量的影响。结果表明，黄泛沙区中低产田冬小麦钾素与N、P、Zn配合施用的最佳经济施钾量为225～300kg／hm^2，比对照增产17．6％～23．2％，经方差分析达显著水平。钾素能增加穗粒数，提高粒重，提高茎秆充实度，增强抗倒伏能力。     

玉米减量施肥研究

在吉林通化市长年高施肥量(N180kg／hm^2，P2O5 70kg／hm^2)的玉米栽培区，实行减量施肥效果明显。1999年在暗棕壤上试验，用氮量降低23kg／hm^2(实际用氮量150kg／hm^2)，比高施氮量的增产10％左右，2001～2002年分别在冲积土和白浆土上试验，用氮量降低36kg／hm^2(实际用氮量144kg／hm^2)，比高施氮量的分别增产5．65％、2．56％。1995年在白浆土和暗棕壤上试验，施P205量在36．6～91．8kg／hm^2间，形成的玉米产量没有本质上的差异，即多施磷和少施磷的效果是一样的。据此，吉林省东部地区玉米施氮量应由目前180kg／hm^2，减为140～150kg／hm^2，施P2O5量由目前70kg／hm^2，减为35～45kg／hm^2。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.