Early growth and final yield of autumn sownVicia faba L cultivars given different forms of fertiliser N over winter

Summary Between 3 Nov. 1983 and 9 Apr. 1984, six applications of fertiliser N (ammonium, nitrate or urea) were given to four autumn sown (26 Oct. 1983)Vicia faba L cultivars, Banner Winter (BW) and Maris Beagle (MBg), cold tolerant cultivars normally sown in the autumn, and Herz Freya (HF) and Maris Bead (MBd), cold sensitive cultivars more commonly sown in the spring. The effects of additional N were determined by comparison with plants given zero-N (controls). Application of N, regardless of form, had no effect on % emergence at the first sampling (15 Dec. 1983); >90% for BW, MBg and HF, but only 40–60% for MBd. At this time the dry weight, carbon content and nitrogen content of all cultivars was approximately 20% less than that of the seed on planting. No more plants emerged after 15 Dec. 1983. Between 15 Dec. 1983 and 20 Feb. 1984, all cultivars, regardless of N treatment, showed little change in dry weight, carbon content and nitrogen content but the proportion of total plant dry weight, carbon content and nitrogen content in the cotyledons decreased while the proportions in root, stem and leaf tissue increased. On 20 Feb. 1984 there were no N effects. All cultivars but especially BW and MBg, showed progressive increases in dry weight, carbon content and nitrogen content during the period 20 Feb. 1984 to 8 May 1984. Pooled results for all four cultivars indicated that on 8 May 1984, plants given ammonium and urea had a greater dry weight, carbon content and nitrogen content than controls. At harvest (1–3 Sep. 1984), BW and MBg outyielded (g dw seed m⁻²) HF and MBd. Pooled results for all cultivars indicated that application of N regardless of form gave increased yield and an increased N concentration (mg N g⁻¹ dw) in the seed.     

Prediction of yield in the Rothamsted Park Grass Experiment by Ellenberg indicator values

Abstract. The Rothamsted Park Grass Experiment was established in 1856, with experimental plots subjected to annual applications of fertilizer and twice-yearly cutting of hay. There were two major responses to fertilizer, one reflecting high ammonium-nitrogen and increased acidity and the other reflecting high herbage yield without increased acidity. We calculated mean Ellenberg indicator values for N (nitrogen) and R (soil reaction) for the hay harvested between 1948 and 1975, using both unweighted and abundance-weighted means. Plot Ellenberg values were compared with herbage yield and with fertilizer application rates and published soil data. Annual yield of hay varied from 1.5 to 7.4 t/ha and was well predicted by the unweighted mean Ellenberg N-values (r = 0.91). Relatively large negative residuals from the relationship were found in plots whose soil combined low K and low pH. Soil pH was poorly predicted by the unweighted mean R-value, but showed a moderately good relation with weighted mean R (r = 0.73). The fact that Ellenberg N-values correlated better with yield than with applied nitrogen suggests that they might rather be called productivity values.     

Molecular cytogenetic characterization of Roegneria ciliaris chromosome additions in common wheat

The development of alien addition lines is important both for transferring useful genes from related species into common wheat and for studying the relationship between alien chromosomes and those of wheat. Roegneria ciliaris (2n=4x=28, S^cS^cY^cY^c) is reported to be a potential source of resistance to wheat scab, which may be useful in wheat improvement. The amphiploid common wheat-R. ciliaris and BC₁F₇ or BC₂F₆ derivatives were screened by C-banding, genomic in situ hybridization (GISH), fluorescent in situ hybridization (FISH) and restriction fragment length polymorphism (RFLP) for the presence of R. ciliaris chromatin introgressed into wheat. Six lines were identified as disomic chromosome additions (DA), one as a ditelosomic addition (Dt), two as double disomic additions (dDA) and one as a monosomic chromosome addition (MA). RFLP analysis using wheat homoeologous group-specific clones indicated that the R. ciliaris chromosomes involved in these lines belong to groups 1, 2, 3, 5 and 7. The genomic affinities of the added R. ciliaris chromosomes were determined by FISH analysis using the repetitive sequence pCbTaq4.14 as a probe. These data suggest that the R. ciliaris chromosomes in five lines belong to the S^c genome. Based on the molecular cytogenetic data, the lines are designated as DA2S^c#1, Dt2S^c#1L, DA3S^c#1, dDA1S^c#2+5Y^c#1, DA5Y^c#1, DA7S^c#1, DA7Y^c#1 and MA?Y^c#1. Based on the present and previous work, 8 of the 14 chromosomes of R. ciliaris have been transferred into wheat.     

Synthesis of dual-action parthenolide prodrugs as potent anticancer agents

Cancer stem cells are responsible for the failure of a large number of cancer treatments and the re-emergence of cancer in patients. Parthenolide is a potent anticancer sesquiterpene lactone that is also able to kill cancer stem cells. The main problem with this compound is its poor solubility in water. To solve this problem, medicinal chemists have tried to prepare amino-derivatives of parthenolide, however, most amino-derivatives have less potency than that of parthenolide. In this paper, we proposed a new approach to synthesize parthenolide derivatives with better solubility and higher potency. We prepared novel parthenolide derivatives through the aza-Michael addition of nitrogen-containing anticancer drug molecules (cytarabine and melphalan) to the α-methylene-γ-lactone group of parthenolide. Different types of catalysts were used to catalyze the aza-Michael addition. Among all the used catalysts, 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) was found to have the highest catalytic activity. In addition, we examined the effects of parthenolide-anticancer drug hybrids on the growth and proliferation of three cancer cell lines (MCF-7, LNcaP, Hep G2) and CHO. The parthenolide prodrugs showed potent cytotoxic property with IC₅₀ values ranging from 0.2 to 5.2 μM, higher than those of parthenolide and anticancer drugs (cytarabine and melphalan).     

Leaching losses of nitrogen from a clay soil under grass and cereal crops in Finland

Summary A 16-plot experimental field was established in 1975 on a clay soil in Jokioinen, Finland. The water discharge through tile drains was measured and its ammonium and nitrate N contents determined for each plot separately. The surface runoff was also measured and analysed. The annual runoff and the N leached from the surface of moderately fertilized (100 kg/ha/y N) cereal plots varied during 1976–1982 from 21 to 301 mm and from 2 to 7 kg/ha, respectively. The discharge of water and leaching of N through subdrains varied from 65 to 225 mm and from 1 to 38 kg/ha, respectively. The highest leaching was probably caused by a previous fallow. The annual N uptake by the crop varied between 41 and 122 kg/ha.Of the fertilizer-N used for cereals, 20% of that applied in the autumn was lost, but only 1 to 4 per cent was lost when applied in the spring. There was much less N leaching from ley than from barley plots, although the former was given twice as much N. The rate of N fertilization had only a very slight effect on N leaching from both ley and barley plots.The results were compared with those obtained in lysimeters filled with clay, silt, sand and peat soils. No definite conclusions can be drawn because the lysimeter experimental data are only for the first year.     

Assessment of nitrogen flows into the Cuban landscape

The alteration of the nitrogen (N) cycle by human activities is widespread and has often resulted in increased flows of nitrogen to the marine environment. In this paper we have attempted to know the changes of N fluxes in Cuba by quantifying the N inputs to the landscape from (1) fertilizer applications, (2) atmospheric deposition, (3) biological nitrogen fixation and (4) net import of food and feeds. N-inputs to the country progressively increased until the end of the 20th century, reaching a peak during the 80s when low cost fertilizer imported from the former Soviet Union led to heavy rates of application. This rapid growth represented more than a 5-fold increase with respect to pristine values; higher than the two-fold global increase of anthropogenic N reported by Vitousek et al. (1997 Human alteration of the global nitrogen cycle: sources and consequences. Ecol. Appl. 7:737–750). Inorganic fertilizer was the largest single source of reactive N, followed by atmospheric deposition, biological fixation, and net imports of foods and feedstocks. Nitrogen inputs peaked in 1987 and data expressed on an area basis show that N flux to the Cuban landscape, in the 80s, was one of the highest reported in the literature. During the 90s, there was a dramatic drop in nitrogen inputs mainly associated to a decrease in the use of inorganic fertilizer. Other factors reducing nutrient inflows to Cuba, during the same period, were imports of foodstuff and livestock feeds, a decrease of nitrogen oxide emissions, and a decrease in the sugar cane crop area. Using an empirical relationship (Howarth et al. 1996 Regional nitrogen budgets and riverine N & O fluxes for the drainages to the North Atlantic Ocean: Natural and human influences. Biogeochemistry 35:75–139) we present a very preliminary estimate of N-inputs to coastal waters and discuss the consequences of these changes on the coastal zone.     

Effect of nutrient level on competition intensity in the field for three coexisting grass species

A field experiment encompassing both neighbour- and nutrient-manipulations was conducted in a nutrient-impoverished old-field habitat to investigate how the intensity of plant competition was affected by soil nutrient level. Three perennial grasses were used as target species: Agropyron repens, Poa pratensis and Phleum pratense. Neighbour manipulations involved the removal (through herbicide application) of all neighbouring vegetation within a 20 cm or 40 cm radius around target plants. Target performance was measured under five levels of added nutrients (N-P-K) in both the neighbour-removal plots and in non-removal (control) plots. Both neighbour and nutrient manipulations had a highly significant effect on both biomass and tiller production but the interaction between these treatments was generally insignificant. Below-ground/above-ground biomass quotient was affected only by neighbour manipulations and was greatest in the control plots (with no neighbours removed) for all three species. The suppressive effect of neighbours was not markedly affected by nutrient level. However, yield suppression showed a significant decreasing trend with increasing nutrient level for biomass production in Agropyron and an increasing trend for tiller production in Phleum. For Poa, there was no trend in the intensity of competition across nutrient level. The results suggest that the general intensity of competition within this community neither increases nor decreases with increasing nutrient level. Rather, coexisting species appear to respond individually in terms of the intensity of competition that they experience. These results conflict with predictions from the triangular C-S-R model of plant strategies. However, they are consistent with a recently modified ‘habitat templet’ model for vegetation.     

Patch dynamics in grazed subtropical native pastures in south‐east Queensland

Abstract Patch formation is common in grazed grasslands but the mechanisms involved in the formation and maintenance of patches are not clear. To increase our knowledge on this subject we examined possible reasons for patch formation and the influence of management on changes between patch states in three experiments in native pasture communities in the Crows Nest district, south‐east Queensland. In these communities, small‐scale patches (tall grassland (dominated by large and medium tussock grasses), short swards (dominated by short tussock grasses and sedges), and lawns (dominated by stoloniferous and/or rhizomatous grasses)) are readily apparent. We hypothesized that the formation of short sward and lawn patches in areas of tall grassland was due to combinations of grazing and soil fertility effects. This was tested in Experiment 1 by applying a factorial combination of defoliation, nutrient application and transplants of short tussock and stoloniferous species to a uniform area of tall grassland. Total species density declined during the experiment, was lower with high nutrient applications, but was not affected by defoliation. There were significant changes in abundance of species that provided support for our hypotheses. With light defoliation and low nutrients, the tall grassland remained dominated by large tussock grasses and contained considerable amounts of forbs. With heavy defoliation, the pastures were dominated by medium tussock grasses and there were significant decreases in forbs and increases in sedges (mainly with low nutrients) and stoloniferous grasses (mainly with high nutrients). Total germinable seed densities and those of most species groups were significantly lower in the heavy defoliation than the light defoliation plots. Total soil seed numbers were not affected by nutrient application but there were fewer seeds of the erect forbs and more sedge seeds in plots with high nutrients. The use of resting from grazing and fire to manage transitions between patches was tested. In Experiment 2 , changes in species density and abundance were measured for 5 years in the three patch types with and without grazing. Experiment 3 examined the effects of fire, grazing and resting on short sward patches over 4 years. In Experiment 2 , total species density was lower in lawn than short sward or tall grassland patches, and there were more species of erect forbs than other plant groups in all patch types. The lawn patches were originally dominated by Cynodon spp. This dominance continued with grazing but in ungrazed patches the abundance of Cynodon spp. declined and that of forbs increased. In the short sward patches, dominance of short tussock grasses continued with grazing but in ungrazed plots their abundance declined while that of large tussock grasses increased. The tall grassland patches remained dominated by large and medium tussock species. In Experiment 3 , fire had no effect on species abundance. On the grazed plots the short tussock grasses remained dominant but where the plots were rested from grazing the small tussock grasses declined and the large tussock grasses increased in abundance. The slow and relatively small changes in these experiments over 4 or 5 years showed how stable the composition of these pastures is, and that rapid changes between patch types are unlikely.     

Impact of Microzooplankton and Copepods on the Growth of Phytoplankton in the Yellow Sea and East China Sea

Dilution and copepod addition incubations were conducted in the Yellow Sea (June) and the East China Sea (September) in 2003. Microzooplankton grazing rates were in the range of 0.37–0.83 d⁻¹ in most of the experiments (except at Station A3). Correspondingly, 31–50% of the chlorophyll a (Chl a) stock and 81–179% of the Chl a production was grazed by microzooplankton. At the end of 24 h copepod addition incubations, Chl a concentrations were higher in the copepod-added bottles than in the control bottles. The Chl a growth rate in the bottles showed good linear relationship with added copepod abundance. The presence of copepods could enhance the Chl a growth at a rate (Z) of 0.03–0.25 (on average 0.0691) d⁻¹ ind⁻¹ l. This study, therefore parallels many others, which show that microzooplankton are the main grazers of primary production in the sea, whereas copepods appear to have little direct role in controlling phytoplankton.     

Studies on Chlorosis-Inducing Activities and Plant Growth Inhibition of Benzophenone Derivatives

Some benzophenones substituted with methyl, methoxy, hydroxy or halogen groups inhibited growth and induced chlorosis in various plants. The structure activity relationships about the chlorosis-inducing activity and the growth inhibitory activity of the 3-methyl-benzophenones were well expressed by use of hydrophobic contant π, and Hammett’s σ. The highest selectivity for phytotoxic activities against barnyardgrass and the rice plant was with 3,3′-dimethyl-4-methoxybenzophenone (Methoxyphenone).