Weed seedbank responses to 12 years of applications of composts,animal slurries or mineral fertilisers     

B DE CAUWER  K VAN DEN BERGE  M COUGNON  R BULCKE  D REHEUL 《Weed Research》2010,50(5):425-435

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Effects of photoperiod on leaf greenness of four bedding plant species     

F. A. Langton  K. E. Cockshull 《The Journal of Horticultural Science and Biotechnology》2013,88(3):400-404

Summary

Short-day (SD) and long-day (LD) photoperiodic treatments were compared, at equal light integral, for their effects on the seedling growth of four bedding plant species: geranium, impatiens, pansy and petunia. Total leaf area was frequently increased by LD given either by day-extension lighting or night-break lighting, but this response was inconsistent and varied greatly between species and experiments. In contrast, leaf greenness measured using a SPAD-502 meter, a measure of chlorophyll content per unit area of leaf, was consistently and significantly increased in LD in all four species. However, night-break lighting may have been somewhat less effective than day-extension lighting. Increasing the day-extension lighting from 16 h to 24 h gave no further intensification of greenness. Consistent with increases in leaf greenness, total dry weight was generally increased in LD, and increases were of a similar magnitude to those given by doubling the daily light integral. The promotional effect of LD on chlorophyll content appears to have been largely ignored or overlooked in recent years, but this may be because simple methods for measuring ‘greenness’ have only recently become widely available.  相似文献   

Composting Short Paper Fiber with Broiler Litter and Additives: Part I: Effects of Initial pH and Carbon/Nitrogen Ratio On Ammonia Emission     

Ekinci K.  H.M. Keener  D.L. Elwell 《Compost science & utilization》2013,21(2):160-172

Short paper fiber (SPF), a by-product of the paper mill industry, was cocomposted with broiler litter (BL) to determine decomposition rate and NH₃-N loss as functions of C/N ratio and pH of the compost mixes. The SPF generally had a high C/N ratio >200 while the BL, consisting of bedding material (sawdust) and poultry manure, had a low C/N ratio of 10–12. A total of seven series (27 tests) of pilot-scale studies were conducted using two different SPFs mixed with BL. Additives used for pH control were alum (aluminum sulfate), HiClay® Alumina and sulfuric acid. Mixing ratios [SPF/(SPF+BL), kg/kg(dry basis)] used were 0.8 to 0.4. Test conditions were C/N of 17 to 49, pH of 6.6 to 8.3, initial temperatures of ?1 to 22°C, composting temperature of 60°C, water content of 50-55% w.b. and remixing two times per week. Composting temperature was controlled using forced ventilation with a high/low fan setting. Composting trials lasted two weeks. Ammonia loss, O₂, CO₂, compost temperatures and dry solids loss were measured. Evaluations of ammonia emissions versus initial C/N and pH showed: (1) NH₃-N loss decreased as initial C/N increased, even above C/N = 38; (2) NH3-N loss decreased rapidly below pH = 7 and increased rapidly for initial pH above 8. Addition of alum and/or sulfuric acid was found to decrease NH₃- N loss while HiClay® Alumina had little or no effect. Results on dry solids loss are not presented in this article.  相似文献   

Multivariate analysis and genetic diversity for morphometric and root textural quality traits in ashwagandha (Withania somnifera Dunal)     

R. Ramesh Kumar  L. Prasanna Anjaneya ReddyJ. Vinay Kumar  K. KomaraiahS. Purnanand  K.P. Sastry 《Industrial Crops and Products》2012,35(1):199-202

Ashwagandha (Withania somnifera) is an important medicinal plant and its dried roots are used in traditional systems of medicine. The market price of roots is determined by physical (textural) quality. Brittle roots with high starch and low fiber are considered to be superior because of ease in grinding. Genetic diversity studies based on root textural parameters have not been done so far. So the present study was designed to assess genetic diversity for morphometric traits and root textural quality parameters among two morphologically distinct groups: Poshita and Nagore. The PCA separated the morphometric and root texture variables distinctly into two different principal components: PC-1 and PC-2 respectively, indicating that both are negatively associated. All the morphotypes in Poshita group showed high positive loadings in PC-1 indicating that component genotypes are high root yielding. Nagore morphotypes were low yielding but the root texture was good. Clustering of morphotypes grouped Poshita and Nagore separately with high inter-cluster distances indicating that both groups are highly divergent from each other, suggesting that there is sufficient scope for varietal improvement through hybridization.  相似文献   

Effect of glyphosate on the tripartite symbiosis formed by Glomus intraradices,Bradyrhizobium japonicum,and genetically modified soybean     

Jeff R. Powell  Rachel G. Campbell  Kari E. Dunfield  Robert H. Gulden  Miranda M. Hart  David J. Levy-Booth  John N. Klironomos  K. Peter Pauls  Clarence J. Swanton  Jack T. Trevors  Pedro M. Antunes 《Applied soil ecology》2009,41(1):128-136

Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N₂-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N₂-fixation. We did observe evidence of the response of one symbiont (stimulation of N₂-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.  相似文献   

Genetic shifts in smooth bromegrass under grazing: changes in nutritional value and preference for surviving vs. original genotypes     

L. K. Falkner  & M. D. Casler 《Grass and Forage Science》2000,55(4):351-360

Genetic shifts in plant morphology and reproductive characters under grazing may potentially affect nutritive value and preference. This research was conducted to determine the response of smooth bromegrass ( Bromus inermis Leyss.) populations to long-term grazing. Genotypes from five populations of smooth bromegrass that survived 9 years of grazing were compared with genotypes of each population grown from original seed. Plant height was measured and biomass estimated for each genotype, before and after grazing by sheep, in order to assess preference. Genotypes were also tested for nutritive value. The selective effect of competition during establishment and maintenance under grazing was accompanied by genetic shifts in smooth bromegrass plants in these pastures. Survivors had greater plant biomass despite having a decrease in plant height of up to 5%. Preference for survivors, quantified as percentage consumption by sheep, was up to 3% units less than for original populations. The nutritive value of survivors was similar to that of original populations, except for one population, which had a lower neutral-detergent fibre among the survivors after grazing.  相似文献   

Co-incorporation of biodegradable wastes with crop residues to reduce nitrate pollution of groundwater and decrease waste disposal to landfill     

C. R. Rahn    G. D. Bending    R. D. Lillywhite  & M. K. Turner 《Soil Use and Management》2009,25(2):113-123

Return of high nitrogen (N) content crop residues to soil, particularly in autumn, can result in environmental pollution resulting from gaseous and leaching losses of N. The EU Landfill Directive will require significant reductions in the amounts of biodegradable materials going to landfill. A field experiment was set up to examine the potential of using biodegradable waste materials to manipulate losses of N from high N crop residues in the soil. Leafy residues of sugar beet were co‐incorporated into soil with materials of varying C:N ratios, including molasses, compactor waste, paper waste, green waste compost and cereal straw. The amendment materials were each incorporated to provide approximately 3.7 t C per hectare. The most effective material for reducing nitrous oxide (N₂O) production and leaching loss of NO₃^? was compactor waste, which is the final product from the recycling of cardboard. Adding molasses increased N₂O and NO₃^? leaching losses. Six months following incorporation of residues, the double rate application of compactor waste decreased soil mineral N by 36 kg N per hectare, and the molasses increased soil mineral N by 47 kg N per hectare. Compactor waste reduced spring barley grain yield by 73% in the first of years following incorporation, with smaller losses at the second harvest. At the first harvest, molasses and paper waste increased yields of spring barley by 20 and 10% compared with sugar beet residues alone, and the enhanced yield persisted to the second harvest. The amounts of soil mineral N in the spring and subsequent yields of a first cereal crop were significantly correlated to the lignin and cellulose contents of the amendment materials. Yield was reduced by 0.3–0.4 t/ha for every 100 mg/g increase in cellulose or lignin content. In a second year, cereal yield was still reduced and related to the cellulose content of the amendment materials but with one quarter of the effect. Additional fertilizer applied to this second crop did not relieve this effect. Although amendment materials were promising as tools to reduce N losses, further work is needed to reduce the negative effects on subsequent crops which was not removed by applying 60 kg/ha of fertilizer N.  相似文献   

Mechanical transmission of maize rayado fino marafivirus (MRFV) to maize and barley by means of the vascular puncture technique     

K. Madriz-Ordeñana  R. Rojas-Montero  T. Lundsgaard  P. Ramírez  H. Thordal-Christensen  & D.B. Collinge 《Plant pathology》2000,49(2):302-307

Maize rayado fino marafivirus (MRFV) was mechanically transmitted to kernels of three Costa Rican maize cultivars by the vascular puncture technique. A transmission rate of up to 43.2% was obtained for cultivar HC-57. The rate of MRFV transmission to maize was possibly affected by the morphology of the kernel, which may influence physical access to the vascular tissue after water imbibition. Transmission to maize was confirmed by western blot and immunosorbent electron microscopy. By slight modifications of the procedure, MRFV was also transmitted to barley. This is the first report of MRFV infecting a species outside the supertribe Andropogonodae. Virus infection and replication in barley were confirmed by RT-PCR detection of MRFV RNA and by detection of the virus by ELISA.  相似文献   

Metabolic differentiation of bloodstream forms of Trypanosoma brucei brucei into procyclic forms. Effect of hydroxyurea, arabinosyl adenine, and serum omission   总被引：1，自引：0，他引：1  

A Markos  A Blah?sková  M Kalous  E Bysková  K Byska  E Nohynková 《Folia parasitologica》1989,36(3):225-238

Bloodforms of Trypanosoma brucei brucei STIB 247 taken from rats and containing more than 80 per cent short stumpy forms, differentiated in vitro to procyclic forms in medium SDM 79 (Brun and Sch?nenberger 1979), enriched with 3 mmol.dm-3 cis-aconitate. Cell division was abolished by the addition of hydroxyurea (200 micrograms.ml-1) or arabinosyl adenine (20 micrograms.ml-1 to the cultivation medium, or by the omission of serum from the medium. The ultrastructure of exponentially growing controls was rearranged within 24 h. The endogenous respiration and the respiration stimulated by proline, succinate, and 2-oxoglutarate were detectable within 12 h; after 48 h the respiration rates were comparable to those found in the established procyclic forms. After 12 h the respiration was inhibited by 200 mumol.dm-3 KCN, and by 20 mumol.dm-3 antimycin to the extent found in procyclic forms. Hydroxyurea did not significantly affect respiration. Activities of procyclic-stage enzyme markers malate dehydrogenase, threonine dehydrogenase, succinate: cytochrome c reductase, and NADH: cytochrome c reductase rose within 48 h of differentiation to values which were close to those found in established procyclic forms. The activity of glutamate dehydrogenase (NAD-specific), however, was only 1/3 of that in the procyclics, and no citrate synthase was detected in differentiating culture. Glycosomal malate dehydrogenase was detected after 6 h. In the presence of hydroxyurea or arabinosyl adenine, or in the absence of serum, respiration rates, marker enzyme activities, and glycosomal malate dehydrogenase developed to the extent comparable to the untreated controls. The results suggest that it is possible to separate the process of differentiation from cell proliferation. Cell division is not a necessary prerequisite of differentiation.  相似文献   

Isolation and characterization of a potyvirus associated with bushy dwarf symptom in chickpea, Cicer arietinum, in India     

V. ANJAIAH  D. V. R. REDDY  S. K. MANOHAR  R. A. NAIDU  Y. L. NENE  A. S. RATNA 《Plant pathology》1989,38(4):520-526

A potyvirus that induced stunting and a characteristic bushy appearance at the apical region, due to proliferation of terminal branches with narrowed, reduced and deformed leaflets, was isolated from chickpea in India. The virus was sap-transmissible to 14 species of Chenopodiaceae, Leguminosae, Solanaceae and Malvaceae; Chenopodium amaranticolor was a good local lesion host. Virus particles, trapped by immunosorbent electron microscopy and stained with uranyl acetate, were 710 ×10 nm long. Purified virus preparations contained a single polypeptide species of 32,500 Da and one nucleic acid species of 3.1 · 10⁶ Da. The virus was serologically related to soybean mosaic, azuki bean mosaic and peanut mottle viruses but not to clover yellow vein, pea seed-borne mosaic and bean yellow mosaic viruses.
On the basis of these properties, the virus was identified as a previously undescribed potyvirus in chickpea, for which the name chickpea bushy dwarf virus is proposed.  相似文献