Effects of alternative tillage systems on soil quality and yield of spring cereals on silty clay loam and sandy loam soils in the cool, wet climate of central Norway

Tillage trials were established on a poorly drained silty loam overlying silty clay loam and on a freely drained sandy loam overlying medium sand, in 1988 and 1989, respectively. Autumn and spring ploughing and two ploughless systems were compared for 12–13 years, with three replications at each site. The ploughless treatments comprised deep versus shallow spring harrowing until 1999, and thereafter autumn plus spring harrowing versus spring harrowing only. In 6 years, treatments with and without fungal spraying of the cereal crops were included. In other years, fungicides were not used. Perennial weeds were controlled by herbicides as necessary, on nine occasions up until 2001. Average spring barley (Hordeum vulgare L.) and spring oat (Avena sativa L.) yields were similar with spring ploughing as with autumn ploughing at both sites. In treatments without ploughing, average yields on the silty loam over clay were 93% of those obtained with ploughing, and on the sandy loam over sand they were 81%. Smaller and non-significant yield differences were found between spring harrowing versus deep spring harrowing, and between autumn plus spring harrowing versus spring harrowing only. Fungal spraying increased yields markedly at both sites (25%), but there was no significant interaction between this treatment and tillage system. Oat was compared with barley in 2 years, with oat performing better under ploughless tillage. At both sites increases in penetrometer resistance occurred in the topsoil of unploughed treatments. These were considered particularly limiting on the sandy loam. On the silty loam there was an increase in surface horizon porosity in the absence of ploughing, which was associated with an increase in topsoil organic matter content. On this soil there was also a tendency toward lower penetrometer resistance at >30 cm depth on autumn plus spring harrowed soil than on ploughed soil, indicating that the plough pan may have diminished. This was supported by observations of greater earthworm activity on unploughed soil. Soil chemical analyses revealed that mineral N and plant-available P and K accumulated in the upper horizon under ploughless tillage. The percentage yields obtained in individual years with autumn as opposed to spring ploughing, were positively correlated with air temperature during 0–4 weeks after planting on the silty loam, and with precipitation during 0–12 weeks after planting on the sandy loam. In the case of yields obtained with spring harrowing only, relative to spring ploughing, positive correlations were found with 0–4 week temperature on both soil types, suggesting that low early season temperatures may limit yields under ploughless tillage.     

Crop responses to applied soil compaction and to compaction repair treatments

Crop responses to annual compaction treatments (applied to whole plots) and management treatments to ameliorate compacted soil were determined in a field experiment on a Vertisol. Initially, all treatments except a control were compacted with a 10 Mg axle load on wet soil (26% gravimetric water content compared with a plastic limit of 22%). Annually applied axle loads of 10 and 6 Mg on wet soil (25–32% soil water) tended to reduce seedling emergence, grain yield (wheat, sorghum and maize), soil water storage and crop water use efficiency (WUE). Annual applications of an axle load of 6 Mg on dry soil (<22% soil water) had little effect on crop performance. Mean reductions in the yield of five crops (three wheat, one sorghum and one maize) in comparison with the uncompacted control were 23% or 0.79 Mg ha⁻¹ (10 Mg on wet soil), 13% or 0.44 Mg ha⁻¹ (6 Mg on wet soil) and 1% or 0.03 Mg ha⁻¹ (6 Mg on dry soil). Maize grown in the fifth year of treatment application was most affected by compaction of wet soil, its WUE being reduced from 14.3 to 9.7 kg ha⁻¹ mm⁻¹ in response to an axle load of 10 Mg. Reduced WUE was associated with delayed soil water extraction at depth. A 3-year pasture ley was the most successful amelioration treatment. A wheat and a maize crop grown after the ley outyielded the control by 0.33 and 0.90 Mg ha⁻¹, respectively. So the pasture not only ameliorated the initial compaction damage, with respect to crop performance, but resulted in improvements in two subsequent crops.     

Novel fatty acid esters of p-coumaryl alcohol in epicuticular wax of apple fruit

Hexane extracts of epicuticular wax from cv. Gala apples were noted to have an unusual, broad absorbance maximum at approximately 258 nm, which led us to isolate and identify the primary UV-absorbing compounds. Column and thin-layer chromatography yielded a fraction that gave a series of paired, 260-nm-absorbing peaks on C(18) HPLC. These were shown to be a family of phenolic fatty acid esters, for which retention times increased with increasing fatty acid chain length, and paired peaks were esters of two related phenolics with the same fatty acid moiety. Alkaline hydrolysis of the esters released two water-soluble phenolics separable by C(18) HPLC. Electrospray ionization mass spectrometry gave a molecular mass of 150 for both, and (1)H NMR plus UV absorbance spectra identified them as E and Z isomers of p-coumaryl alcohol. Alkaline cleavage of the fatty acid esters in the presence of methanol or ethanol resulted in partial derivatization of E-p-coumaryl alcohol to the corresponding gamma-O-methyl or O-ethyl ether. Gradient HMQC NMR of the HPLC-purified stearate ester of E-p-coumaryl alcohol indicated that fatty acid esterification occurs at the gamma-OH rather than at the 4-OH on the phenyl ring. This is the first report of fatty acid esters of monolignols as a natural plant product.     

Cytochrome oxidase as an indicator of ice storage and frozen storage

The potential of cytochrome oxidase as an indicator of ice storage and frozen storage of fish was investigated. Optimal assay conditions for cytochrome oxidase in a crude homogenate from cod muscle were studied. Maximal cytochrome oxidase activity was found at pH 6.5-7.5 and an assay temperature of 30 degrees C. Maximal activation by Triton X-100 was obtained in a range of 0.62-1.25 mM Triton X-100. The specificity of the assay was high, as cytochrome oxidase was inhibited 98% by 33 microM of the specific inhibitor sodium azide. The coefficient of variation of cytochrome oxidase activity in different cods was 21%, and the coefficient of variation of different analyses on the same homogenate was 5%. It was shown that ice storage of muscle samples before they were frozen and thawed resulted in a major freezing-induced activation of cytochrome oxidase activity. The enzyme may therefore be used as an indicator of frozen fish to determine if the fish has been stored on ice before freezing. Cytochrome oxidase activity showed also potential as an indicator of frozen storage, as it was possible to distinguish between the frozen storage temperatures -9, -20, and -40 degrees C.     

Bioindication of Different Stresses in Forest Decline Studies in Slovenia

Determination of the stresses operating on a forest ecosystem demands the use of several bioindication methods. Air quality indicators were assessed from an inventory of forest decline based on the assessment of tree crowns and epiphytic lichens. Photosynthetic pigments, ascorbic acid and major macronutrients were studied in Norway spruce needles as indicators of physiological and biochemical stress. Analyses were carried out on selected forest plots in polluted areas (Zasavje district, vicinity of thermal power plants) and predominantly unpolluted areas (Triglav National Park, Julian Alps, Slovenia). For some bioindication methods, there was good agreement with measured air quality and climatological parameters. The best agreement was found between total foliar sulphur in needles and epiphytic lichens, especially in more polluted areas. Agreement with forest decline inventories and analyses of some needle stress physiological/biochemical parameters was less convincing. The strength of agreement was further decreased by soil characteristics and climatic parameters, influenced also by biotic parameters and forest stand history and management. It was concluded that there is no simple bioindication method available to evaluate the vitality of a forest.     

Effect of postharvest storage and processing on the antioxidant constituents (flavonoids and vitamin C) of fresh-cut spinach

The effect of modified atmosphere packaging (MAP) and cooking on the flavonoids and vitamin C content (ascorbic + dehydroascorbic acid; AA + DHAA) of fresh-cut spinach was evaluated. The total flavonoid content (approximately 1000 mg kg(-)(1) f.w.) remained quite constant during storage in both air and MAP atmospheres, while vitamin C (750 mg kg(-)(1)f.w.) was better preserved in MAP-stored spinach. AA was transformed to DHAA during storage, and its concentration was higher in MAP-stored tissues. The free-radical scavenging activity of the isolated flavonoids was tested, and only those flavonoids with either a dihydroxyl grouping or acylated with ferulic acid showed significant activity. A decrease in the total antioxidant activity was observed during storage, particularly important in MAP-stored spinach. The higher content of DHAA and lower content of both AA and antioxidant flavonoids in the MAP-stored samples could explain this antioxidant activity decrease. Boiling extracted 50% of total flavonoids and 60% vitamin C in the cooking water. However, flavonoid glucuronides were extracted more in the cooking water than the other glycosides. The vitamin C content of the cooked tissue was higher in those samples stored in MAP.     

Color analysis of storage roots from the USDA,ARS sweetpotato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>) germplasm collection

The United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Plant Genetic Resources Conservation Unit in Griffin, GA maintains the United States germplasm collection for Ipomoea spp. (Convolvulaceae). During 2012–2014, 737 sweetpotato, Ipomoea batatas (L.) Lam., plant introductions (PI) were acquired as tissue-culture plantlets and then acclimated to greenhouse conditions at the USDA, ARS, U. S. Vegetable Laboratory (USVL), Charleston, SC. Single plants were transferred to plastic-covered plant beds to produce cuttings for replicated field trials. Storage roots were harvested from 690 PIs grown in the field and 695 PIs grown in pots. Color coordinates were obtained for each PI using a tristimulus colorimeter. Hue angle values (h*) ranged from 8.2° to 88.3° (\( \bar{x} \) = 54.9°) for the periderm (peel or skin) of field-grown storage roots (n = 690 PIs) and ? 9.4° (= 350.6°) to 96.2° (\( \bar{x} \) = 51.3°) for pot-grown roots (n = 695 PIs). The red–green coordinate (a*) ranged from 0.8 to 30.7 (\( \bar{x} \) = 12.8) for the periderm of field-grown roots and ? 2.0 to 44.9 (\( \bar{x} \) = 16.1) for pot-grown roots. The yellow–blue coordinate (b*) ranged from 2.8 to 33.1 (\( \bar{x} \) = 19.4) for the periderm of field-grown roots and ? 7.4 to 38.1 (\( \bar{x} \) = 19.3) for pot-grown roots. Color saturation (chroma, C*) ranged from 13.7 to 35.8 (\( \bar{x} \) = 24.9) for the periderm of field-grown roots and 14.9–45.5 (\( \bar{x} \) = 29.3) for pot-grown roots. Lightness (white–black, L*) ranged from 32.6 to 81.7 (\( \bar{x} \) = 54.6) for the periderm of field-grown roots and 32.1–88.2 (\( \bar{x} \) = 64.0) for pot-grown roots. Hue angles ranged from ? 13.1° (= 346.9°) to 100.9° (\( \bar{x} \) = 80.9°) for the stele (flesh) of field-grown storage roots (n = 672 PIs) and ? 29.9° to 103.5° (\( \bar{x} \) = 81.6°) for pot-grown roots (n = 676 PIs); a* ranged from ? 5.6 to 35.0 (\( \bar{x} \) = 8.0) for the stele of field-grown roots and ? 6.0 to 41.0 (\( \bar{x} \) = 7.6) for pot-grown roots; and b* ranged from ? 7.7 to 56.1 (\( \bar{x} \) = 34.6) for the stele of field-grown roots and ? 12.6 to 56.1 (\( \bar{x} \) = 31.8) for pot-grown roots. C* ranged from 12.7 to 65.8 (\( \bar{x} \) = 37.2) for the stele of field-grown roots and 8.9–65.7 (\( \bar{x} \) = 34.5) for pot-grown roots; and L* ranged from 27.8 to 91.1 (\( \bar{x} \) = 77.7) for the stele of field-grown roots and 28.2–91.9 (\( \bar{x} \) = 80.4) for pot-grown roots. There were significant relationships between stele color (h*) and percent dry matter, with orange stele having a significantly lower % dry matter (\( \bar{x} \) = 25.6%, n = 183) compared with roots with cream/white stele (\( \bar{x} \) = 30.8%, n = 373). There appears to be wide genetic diversity for root color characteristics for the United States sweetpotato germplasm collection.     

Content and composition of essential oil and content of rosmarinic acid in lemon balm and balm genotypes (<Emphasis Type="Italic">Melissa officinalis</Emphasis>)

Lemon balm (Melissa officinalis L.) is used since ancient times because of its sedative, spasmolytic and antiviral effects. Its therapeutic impact is due to the content of essential oil and rosmarinic acid. A set of 68 M. officinalis genotypes was evaluated for content and composition of essential oil and the content of rosmarinic acid. For all genotypes the level of ploidy was determined. The 68 genotypes were clone plants grown and evaluated for two years at Quedlinburg. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil varied in this study in ranges from 0.03 to 0.33% for the second cut 2010 and 0.01–0.35% for the second cut 2011. The rosmarinic acid content ranged in the year 2010 from 3.67 to 7.55% and in the year 2011 from 4.92 to 8.07%. Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype β-caryophyllene oxide. Ploidy was determined for all genotypes and two cytotypes were found: diploid 2n = 2x = 32 (62 of 68 genotypes) and triploid 2n = 3x = 48 (6 of 68 genotypes).     

Inhibition on human liver cytochrome P450 3A4 by constituents of fennel (Foeniculum vulgare): identification and characterization of a mechanism-based inactivator

Fennel, a seed of Foeniculum vulgare, is used as a culinary spice and traditional medicine. The methanolic extract of fennel showed a characteristic of mechanism-based inactivation on erythromycin N-demethylation mediated by human liver microsomal cytochrome P450 3A4 (CYP3A4). The present study was conducted to identify the fennel constituent having the inhibition. Thirteen compounds have been isolated from a methanol extract of fennel and tested for their inhibition on CYP3A4. Among them, 5-methoxypsoralen (5-MOP) showed the strongest inhibition with an IC50 value of 18.3 microM and a mixed type of inhibition. In addition, with the preincubation time of 20 min only 5-MOP showed preincubation time dependency; the IC50 value decreased from 18.3 microM with a preincubation time of 0 min to 4.6 microM with a preincubation time of 20 min. Further investigation on 5-MOP showed the characteristics of time-dependent inhibition, requirement of NADPH, lack of protecting effect of nucleophiles, and recovery of CYP3A4 activity by the competitive inhibitor. This result suggests that the inhibitory activity of CYP3A4 by 5-MOP was a mechanism-based inactivation. The kinetic parameter for mechanism-based inactivation was characterized by a KI value of 15.0 microM and a kinact value of 0.098 min(-1).     

Sludge-derived organic carbon in an agricultural soil estimated by 13C abundance measurements

The objective of this study is to develop a method to follow the dynamics of sludge‐derived organic carbon, which will allow us to understand the behaviour of trace metals in the sludge‐treated soils. We studied, in a sandy agricultural soil of southwest France, cultivated with maize and amended with sewage‐sludge over 20 years, the dynamics of different sources of organic matter and compared this with a control, which had never received any treatment. For the first time, a method is proposed that will distinguish and quantify sludge‐derived organic carbon, maize‐derived organic carbon, and native organic carbon. This method is based on the mean differences in δ¹³C abundances between native (−26.5‰), maize (−12.5‰) and sludge (−25.4‰) organic carbon. Three hypotheses on the dynamics of soil organic matter sources are proposed: (i) isotopic differences observed between control and sludge‐treated soils are due only to the incorporation of sludge C, whereas in the others, the control was used to model the incorporation of (ii) maize C or (iii) native C in the sludge‐treated soils. The comparison of the stocks of each source (native C, maize C and sludge C) found in the bulk soil with the sum of corresponding stocks found in particle‐size fractions allowed us to reject the two first hypotheses and to validate the last one. Repeated applications of sewage‐sludge induced accumulation of sludge‐derived organic carbon in the topsoil, and simultaneously contributed to the preservation of maize‐derived organic carbon. When sludge applications ceased, the rapid decrease in soil organic matter stocks was mostly caused by the degradation of the sludge‐derived organic carbon sources. At the same time, the maize‐derived organic carbon shifted from the coarsest fraction (200–2000 μm) to the finest fraction (0–50 μm). Therefore, this study has shown that repeated applications of sewage‐sludge induced changes in soil organic matter dynamics over time.