96 resultados para Soilless cultivation
Resumo:
When does Neolithic life begin in Britain? The author gathered up the current evidence for radiocarbon-dated first use of cereals, distinguishing between dates from charcoal in contexts with cereals, and dates from the charred grains themselves. The charred grains begin to appear around 4000 cal BC and become prominent in settlements between 3800 and 3000 cal BC This correlates well with the appearance of megalithic tombs (3800-3500 cal BC) and argues for a relatively rapid adoption of the Neolithic package during an experimental phase of two centuries, 4000-3800 cal BC. The early cereals reported in the pollen record (from 5000 BC) are attributed to wild species.
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This paper summarizes some of the geoarchaeological evidence for early arable agriculture in Britain and Europe, and introduces new evidence for small-scale but very intensive cultivation in the Neolithic, Bronze Age and Iron Age in Scotland. The Scottish examples demonstrate that, from the Neolithic to the Iron Age, midden heaps were sometimes ploughed in situ; this means that, rather than spreading midden material onto the fields, the early farmers simply ran an ard over their compost heaps and sowed the resulting plots. The practice appears to have been common in Scotland, and may also have occurred in England. Neolithic cultivation of a Mesolithic midden is suggested, based on thin-section analysis of the middens at Northton, Harris. The fertility of the Mesolithic middens may partly explain why Neolithic farmers re-settled Mesolithic sites in the Northern and Western Isles.
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Consumption of green leafy vegetables is associated with reduced risk of several types of cancer and cardiovascular disease. These beneficial effects are attributed to a range of phytochemicals including flavonoids and glucosinolates, both of which are found in high levels in Brassicaceous crops. Rocket is the general name attributed to cultivars of Eruca sativa and Diplotaxis tenufolia, known as salad rocket and wild rocket, respectively. We have shown that different light levels during the cultivation period of these crops have a significant impact on the levels of flavonoids present in the crop at harvest, with over 15-fold increase achieved in quercetin, isorhamnetin, and cyanidin in high light conditions. Postharvest storage further affects the levels of both flavonoids and glucosinolates, with cyanidin increasing during shelf life and some glucosinolates, such as glucoiberverin, being reduced over the same storage period. In vitro assays using human colon cell lines demonstrate that glucosinolate-rich extracts of Eruca sativa cv. Sky, but not Diplotaxis tenufolia cv. Voyager, confer significant resistance to oxidative stress on the cells, which is indicative of the chemoprotective properties of the leaves from this species. Our findings indicate that both pre and postharvest environment and genotypic selection, when developing new lines of Brassicaceous vegetables, are important considerations with the goal of improving human nutrition and health.
Resumo:
Runoff, sediment, total phosphorus and total dissolved phosphorus losses in overland flow were measured for two years on unbounded plots cropped with wheat and oats. Half of the field was cultivated with minimum tillage (shallow tillage with a tine cultivator) and half was conventionally ploughed. Within each cultivation treatment there were different treatment areas (TAs). In the first year of the experiment, one TA was cultivated up and down the slope, one TA was cultivated on the contour, with a beetle bank acting as a vegetative barrier partway up the slope, and one had a mixed direction cultivation treatment, with cultivation and drilling conducted up and down the slope and all subsequent operations conducted on the contour. In the second year, this mixed treatment was replaced with contour cultivation. Results showed no significant reduction in runoff, sediment losses or total phosphorus losses from minimum tillage when compared to the conventional plough treatment, but there were increased losses of total dissolved phosphorus with minimum tillage. The mixed direction cultivation treatment increased surface runoff and losses of sediment and phosphorus. Increasing surface roughness with contour cultivation reduced surface runoff compared to up and down slope cultivation in both the plough and minimum tillage treatment areas, but this trend was not significant. Sediment and phosphorus losses in the contour cultivation treatment followed a very similar pattern to runoff. Combining contour cultivation with a vegetative barrier in the form of a beetle bank to reduce slope length resulted in a non-significant reduction in surface runoff, sediment and total phosphorus when compared to up and down slope cultivation, but there was a clear trend towards reduced losses. However, the addition of a beetle bank did not provide a significant reduction in runoff, sediment losses or total phosphorus losses when compared to contour cultivation, suggesting only a marginal additional benefit. The economic implications for farmers of the different treatment options are investigated in order to assess their suitability for implementation at a field scale.
Resumo:
Red leaf lettuce (Lollo Rosso) was grown under three types of plastic films that varied in transparency to UV radiation (designated as UV block, UV low, and UV window). Flavonoid composition was determined by high-performance liquid chromatography (HPLC), total phenolics by the Folin-Ciocalteu assay, and antioxiclant capacity by the oxygen radical absorbance capacity (ORAC) assay. Exposure to increased levels of UV radiation during cultivation caused the leaves to redden and increased concentrations of total phenols and the main flavonoids, quercetin and cyanidin glycosides, as well as luteolin conjugates and phenolic acids. The total phenol content increased from 1.6 mg of gallic acid equivalents (GAE)/g of fresh weight (FW) for lettuce grown under UV block film to 2.9 and 3.5 mg of GAE/g of FW for lettuce grown under the UV low and UV window films. The antioxiclant activity was also higher in lettuce exposed to higher levels of UV radiation with ORAC values of 25.4 and 55.1 mu mol of Trolox equivalents/g of FW for lettuce grown under the UV block and UV window films, respectively. The content of phenolic acids, quantified as caffeic acid, was also different, ranging from 6.2 to 11.1 mu mol/g of FW for lettuce cultivated under the lowest and highest UV exposure plastic films, respectively. Higher concentrations of the flavonoid glycosides were observed with increased exposure to UV radiation, as demonstrated by the concentrations of aglycones after hydrolysis, which were cyanidin (ranging from 165 to 793 mu g/g), quercetin (ranging from 196 to 880,mu g/g), and luteolin (ranging from 19 to 152 mu g/g). The results demonstrate the potential of the use of UV-transparent plastic as a means of increasing beneficial flavonoid content of red leaf lettuce when the crop is grown in polytunnels.
Resumo:
Red leaf lettuce (Lollo Rosso) was grown under three types of plastic films that varied in transparency to UV radiation (designated as UV block, UV low, and UV window). Flavonoid composition was determined by high-performance liquid chromatography (HPLC), total phenolics by the Folin-Ciocalteu assay, and antioxiclant capacity by the oxygen radical absorbance capacity (ORAC) assay. Exposure to increased levels of UV radiation during cultivation caused the leaves to redden and increased concentrations of total phenols and the main flavonoids, quercetin and cyanidin glycosides, as well as luteolin conjugates and phenolic acids. The total phenol content increased from 1.6 mg of gallic acid equivalents (GAE)/g of fresh weight (FW) for lettuce grown under UV block film to 2.9 and 3.5 mg of GAE/g of FW for lettuce grown under the UV low and UV window films. The antioxiclant activity was also higher in lettuce exposed to higher levels of UV radiation with ORAC values of 25.4 and 55.1 mu mol of Trolox equivalents/g of FW for lettuce grown under the UV block and UV window films, respectively. The content of phenolic acids, quantified as caffeic acid, was also different, ranging from 6.2 to 11.1 mu mol/g of FW for lettuce cultivated under the lowest and highest UV exposure plastic films, respectively. Higher concentrations of the flavonoid glycosides were observed with increased exposure to UV radiation, as demonstrated by the concentrations of aglycones after hydrolysis, which were cyanidin (ranging from 165 to 793 mu g/g), quercetin (ranging from 196 to 880,mu g/g), and luteolin (ranging from 19 to 152 mu g/g). The results demonstrate the potential of the use of UV-transparent plastic as a means of increasing beneficial flavonoid content of red leaf lettuce when the crop is grown in polytunnels.
Resumo:
Lack of sulphur nutrition during potato cultivation has been shown to have profound effects on tuber composition, affecting in particular the concentrations of free asparagine, other amino acids and sugars. This is important because free asparagine and sugars react at high temperatures to form acrylamide, a suspect carcinogen. Free amino acids and sugars also form a variety of other compounds associated with colour and flavour. In this study the volatile aroma compounds formed in potato flour heated at 180 °C for 20 min were compared for three varieties of potato grown, with and without sulphur fertiliser. Approximately 50 compounds were quantified in the headspace extracts of the heated flour, of which over 40 were affected by sulphur fertilisation and/or variety. Many of the 41 compounds found at higher concentrations in the sulphur-deficient flour were Strecker aldehydes and compounds formed from their condensation, whereas only one compound, benzaldehyde, behaved in the same way as did acrylamide and was found at higher concentrations in the sulphur-sufficient flour. The reasons for these effects are discussed.
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Field experiments were conducted in northern Greece in 2003 and 2004 to evaluate effects of tillage regimes (moldboard plowing, chisel plowing, and rotary tilling), cropping sequences(continuous cotton, cotton-sugar beet rotation,and continuous tobacco) and herbicide treatments with inter-row hand hoeing on weed population densities. Total weed densities were not affected by tillage treatment except that of barnyardgrass (Echinochloa crus-galli), which increased only in moldboard plowing treated plots during 2003. Redroot pigweed (Amaranthus retroflexus)and black nightshade (Solanum nigrum) densities were reduced in continuous cotton, while purple nutsedge (Cyperus rotundus), E. crus-galli, S. nigrum, and johnsongras(Sorghum halepense) densities were reduced in tobacco. A. retroflexus and S. nigrum were effectively controlled by all herbicide treatments with inter-row hand hoeing,whereas E. crus-galli was effectively reduced by herbicides applied to cotton and tobacco. S. halepense density reduction was a result of herbicide applied to tobacco with inter-row hand hoeing. Yield of all crops was higher under moldboard plowing and herbicide treatments. Pre-sowing and pre-emergence herbicide treatments in cotton and pre-transplant in tobacco integrated with inter-row cultivation resulted in efficient control of annual weed species and good crop yields. These observations are of practical relevance to crop selection by farmers in order to maintain weed populations at economically acceptable densities through the integration of various planting dates, sustainable herbicide use and inter-row cultivation; tools of great importance in integrated weed management systems. Keywords: cropping sequence, herbicide, integrated weed management, inter-row cultivation,tillage.
Resumo:
This research aimed to investigate the implications of changing agricultural land use from food production towards increased cashew cultivation for food security and poverty alleviation in Jaman North District, Brong-Ahafo Region of Ghana. Based on qualitative, participatory research with a total of 60 participants, the research found that increased cashew production had led to improvements in living standards for many farmers and their children over recent years. Global demand for cashew is projected to continue to grow rapidly in the immediate future and cashew-growing areas of Ghana are well placed to respond to this demand. Cashew farmers however were subject to price fluctuations in the value of Raw Cashew Nuts (RCN) due to unequal power relations with intermediaries and export buyer companies and global markets, in addition to other vulnerabilities that constrained the quality and quantity of cashew and food crops they could produce. The expansion of cashew plantations was leading to pressure on the remaining family lands available for food crop production, which community members feared could potentially compromise the food security of rural communities and the land inheritance of future generations.
Resumo:
Whilst not true in all cases, the microbial communities that chronically infect the airways of patients with CF can vary little over a year despite antibiotic perturbation. The species present tended to vary more between than within subjects, suggesting that each CF airway infection is unique, with relatively stable and resilient bacterial communities. The inverse relationship between community richness and disease severity is similar to findings reported in other mucosal infections.
Resumo:
Due to their broad differentiation potential and their persistence into adulthood, human neural crest-derived stem cells (NCSCs) harbour great potential for autologous cellular therapies, which include the treatment of neurodegenerative diseases and replacement of complex tissues containing various cell types, as in the case of musculoskeletal injuries. The use of serum-free approaches often results in insufficient proliferation of stem cells and foetal calf serum implicates the use of xenogenic medium components. Thus, there is much need for alternative cultivation strategies. In this study we describe for the first time a novel, human blood plasma based semi-solid medium for cultivation of human NCSCs. We cultivated human neural crest-derived inferior turbinate stem cells (ITSCs) within a blood plasma matrix, where they revealed higher proliferation rates compared to a standard serum-free approach. Three-dimensionality of the matrix was investigated using helium ion microscopy. ITSCs grew within the matrix as revealed by laser scanning microscopy. Genetic stability and maintenance of stemness characteristics were assured in 3D cultivated ITSCs, as demonstrated by unchanged expression profile and the capability for self-renewal. ITSCs pre-cultivated in the 3D matrix differentiated efficiently into ectodermal and mesodermal cell types, particularly including osteogenic cell types. Furthermore, ITSCs cultivated as described here could be easily infected with lentiviruses directly in substrate for potential tracing or gene therapeutic approaches. Taken together, the use of human blood plasma as an additive for a completely defined medium points towards a personalisable and autologous cultivation of human neural crest-derived stem cells under clinical grade conditions.
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The characterization of human stem cells for the usability in regenerative medicine is particularly based on investigations regarding their differentiation potential in vivo. In this regard, the chicken embryo model represents an ideal model organism. However, the access to the chicken embryo is only achievable by windowing the eggshell resulting in limited visibility and accessibility in subsequent experiments. On the contrary, ex ovo-culture systems avoid such negative side effects. Here, we present an improved ex ovo-cultivation method enabling the embryos to survive 13 days in vitro. Optimized cultivation of chicken embryos resulted in a normal development regarding their size and weight. Our ex ovo-approach closely resembles the development of chicken embryos in ovo, as demonstrated by properly developed nervous system, bones, and cartilage at expected time points. Finally, we investigated the usability of our method for trans-species transplantation of adult stem cells by injecting human neural crest-derived stem cells into late Hamburger and Hamilton stages (HH26-HH28/E5-E6) of ex ovo-incubated embryos. We demonstrated the integration of human cells allowing experimentally easy investigation of the differentiation potential in the proper developmental context. Taken together, this ex ovo-method supports the prolonged cultivation of properly developing chicken embryos enabling integration studies of xenografted mammalian stem cells at late developmental stages.
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Neural precursor cells (NPCs) are lineage-restricted neural stem cells with limited self-renewal, giving rise to a broad range of neural cell types such as neurons, astrocytes, and oligodendrocytes. Despite this developmental potential, the differentiation capacity of NPCs has been controversially discussed concerning the trespassing lineage boundaries, for instance resulting in hematopoietic competence. Assessing their in vitro plasticity, we isolated nestin+/Sox2+, NPCs from the adult murine hippocampus. In vitro-expanded adult NPCs were able to form neurospheres, self-renew, and differentiate into neuronal, astrocytic, and oligodendrocytic cells. Although NPCs cultivated in early passage efficiently gave rise to neuronal cells in a directed differentiation assay, extensively cultivated NPCs revealed reduced potential for ectodermal differentiation. We further observed successful differentiation of long-term cultured NPCs into osteogenic and adipogenic cell types, suggesting that NPCs underwent a fate switch during culture. NPCs cultivated for more than 12 passages were aneuploid (abnormal chromosome numbers such as 70 chromosomes). Furthermore, they showed growth factor-independent proliferation, a hallmark of tumorigenic transformation. In conclusion, our findings substantiate the lineage restriction of NPCs from adult mammalian hippocampus. Prolonged cultivation results, however, in enhanced differentiation potential, which may be attributed to transformation events leading to aneuploid cells.