Role of Acacia Spp. In Nutrient Balance and Cycling in Regenerating Eucalyptus regnans F. Muell. Forests. II. Field Studies of Acetylene Reduction

1984 ◽  
Vol 32 (2) ◽  
pp. 217 ◽  
Author(s):  
MA Adams ◽  
PM Attiwill
Keyword(s):  
N2 Fixation ◽  
Nutrient Balance ◽  
Sampling Period ◽  
Climatic Conditions ◽  
Severe Drought ◽  
Fresh Weight ◽  
Eucalyptus Regnans ◽  
Acacia Dealbata ◽  
C2h2 Reduction

Rates of C2H2 reduction by nodules of Acacia dealbata growing in 2-year-old Eucalyptus regnans regeneration were determined at monthly intervals for 1 year under field conditions. Intact soil cores containing roots and nodules showed maximum values of 7.1 μmol h-1 g-1 fresh weight of nodules with a mean value of 4.4 μmol h-1 g-1 fresh weight. Nodule mass was clearly related to climatic conditions, being greatest when both temperature and moisture levels were favourable, and was probably depressed during the sampling period by the prevailing severe drought. From the measured rates of C2H2 reduction, estimated N2 fixation was 12-32 kg ha-1 year-1. Rates of N2 fixation as high as this confirm the role of acacias as fast-growing pioneer species important in maintaining the nitrogen pool of the forest ecosystem.

Role of Acacia Spp. In Nutrient Balance and Cycling in Regenerating Eucalyptus regnans F. Muell. Forests. I. Temporal Changes in Biomass and Nutrient Content

1984 ◽  
Vol 32 (2) ◽  
pp. 205 ◽  
Author(s):  
MA Adams ◽  
PM Attiwill
Keyword(s):  
Nutrient Balance ◽  
Nutrient Content ◽  
N Fixation ◽  
Eucalyptus Regnans ◽  
Acacia Species ◽  
Large Numbers ◽  
Calcium Magnesium ◽  
Slash Burning ◽  
Nutrient Conservation

Following severe fire in high-rainfall Eucalyptus regnans forests, several Acacia species may germinate in large numbers. Large amounts of nitrogen, calcium, magnesium and potassium are immobilized in the Acacia biomass, much of which is returned to the soil after canopy closure. Within 3 years of a regeneration burn, 280 kg N ha-1 was in the above-ground Acacia biomass and litter layer. The relative abundance of nitrogen in Acacia spp. is a result of N fixation. The probable rate of N fixation appears significant in relation to losses of nitrogen associated with slash-burning. It is concluded that the Acacia spp. may be important in the secondary succession through nutrient conservation, replacement and redistribution.

scholarly journals Photoprotective Role of Photosynthetic and Non-Photosynthetic Pigments in Phillyrea latifolia: Is Their “Antioxidant” Function Prominent in Leaves Exposed to Severe Summer Drought?

2021 ◽  
Vol 22 (15) ◽  
pp. 8303
Author(s):  
Antonella Gori ◽  
Cecilia Brunetti ◽  
Luana Beatriz dos Santos Nascimento ◽  
Giovanni Marino ◽  
Lucia Guidi ◽  
...  
Keyword(s):  
Photosynthetic Pigments ◽  
Light Stress ◽  
Climatic Conditions ◽  
Photochemical Quenching ◽  
Severe Drought ◽  
Summer Drought ◽  
Photooxidative Stress ◽  
Phillyrea Latifolia ◽  
Antioxidant Function

Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate.

scholarly journals Characteristics of Phomopsis juglandina (Sacc.) Hohn. Associated with Dieback of Walnut in the Climatic Conditions of Southern Romania

Agronomy ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Cristina Mihaescu ◽  
Daniel Dunea ◽  
Adrian Gheorghe Bășa ◽  
Loredana Neagu Frasin
Keyword(s):  
Growth Temperature ◽  
Potential Evapotranspiration ◽  
Optimal Growth ◽  
Climatic Conditions ◽  
Cultural Characteristics ◽  
Optimal Growth Temperature ◽  
Conidial State ◽  
Optimal Ph

Phomopsis juglandina (Sacc.) Höhn., which is the conidial state of Diaporthe juglandina (Fuckel) Nitschke, and the main pathogen causing the dieback of branches and twigs of walnut was recently detected in many orchards from Romania. The symptomatological, morphological, ultrastructural, and cultural characteristics, as well as the pathogenicity of an isolate of this lignicolous fungus, were described and illustrated. The optimum periods for infection, under the conditions prevailing in Southern Romania, mainly occur in the spring (April) and autumn months (late September-beginning of October). Strong inverse correlations (p < 0.001) were found between potential evapotranspiration and lesion lengths on walnut branches in 2019. The pathogen forms two types of phialospores: alpha and beta; the role of beta phialospores is not well known in pathogenesis. In Vitro, the optimal growth temperature of mycelial hyphae was in the range of 22–26 °C, and the optimal pH is 4.4–7. This pathogen should be monitored continuously due to its potential for damaging infestations of intensive plantations.

scholarly journals Intra-Colonial Viral Infections in Western Honey Bees (Apis mellifera)

2021 ◽  
Vol 9 (5) ◽  
pp. 1087
Author(s):  
Loreley Castelli ◽  
María Laura Genchi García ◽  
Anne Dalmon ◽  
Daniela Arredondo ◽  
Karina Antúnez ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Honey Bee ◽  
Viral Infections ◽  
Sampling Period ◽  
Virus Genome ◽  
The Individual ◽  
Bee Virus ◽  
Insight Into ◽  
Bee Viruses

RNA viruses play a significant role in the current high losses of pollinators. Although many studies have focused on the epidemiology of western honey bee (Apis mellifera) viruses at the colony level, the dynamics of virus infection within colonies remains poorly explored. In this study, the two main variants of the ubiquitous honey bee virus DWV as well as three major honey bee viruses (SBV, ABPV and BQCV) were analyzed from Varroa-destructor-parasitized pupae. More precisely, RT-qPCR was used to quantify and compare virus genome copies across honey bee pupae at the individual and subfamily levels (i.e., patrilines, sharing the same mother queen but with different drones as fathers). Additionally, virus genome copies were compared in cells parasitized by reproducing and non-reproducing mite foundresses to assess the role of this vector. Only DWV was detected in the samples, and the two variants of this virus significantly differed when comparing the sampling period, colonies and patrilines. Moreover, DWV-A and DWV-B exhibited different infection patterns, reflecting contrasting dynamics. Altogether, these results provide new insight into honey bee diseases and stress the need for more studies about the mechanisms of intra-colonial disease variation in social insects.

scholarly journals Correction to: The role of plants in the formation of the topsoil chemical composition in different climatic conditions of steppe landscape

2021 ◽  
Author(s):  
Irina Yu. Kudrevatykh ◽  
Pavel I. Kalinin ◽  
Gennady V. Mitenko ◽  
Andrey O. Alekseev
Keyword(s):  
Chemical Composition ◽  
Climatic Conditions

scholarly journals Calibrating the CreditRisk+ Model at Different Time Scales and in Presence of Temporal Autocorrelation †

Mathematics ◽  
2021 ◽  
Vol 9 (14) ◽  
pp. 1679
Author(s):  
Jacopo Giacomelli ◽  
Luca Passalacqua
Keyword(s):  
Time Series ◽  
Default Risk ◽  
Real Life ◽  
Statistical Error ◽  
Real Data ◽  
Sampling Period ◽  
Calibration Procedure ◽  
Industry Standards ◽  
Default Rate

The CreditRisk+ model is one of the industry standards for the valuation of default risk in credit loans portfolios. The calibration of CreditRisk+ requires, inter alia, the specification of the parameters describing the structure of dependence among default events. This work addresses the calibration of these parameters. In particular, we study the dependence of the calibration procedure on the sampling period of the default rate time series, that might be different from the time horizon onto which the model is used for forecasting, as it is often the case in real life applications. The case of autocorrelated time series and the role of the statistical error as a function of the time series period are also discussed. The findings of the proposed calibration technique are illustrated with the support of an application to real data.

scholarly journals Spermine: Its Emerging Role in Regulating Drought Stress Responses in Plants

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 261
Author(s):  
Md. Mahadi Hasan ◽  
Milan Skalicky ◽  
Mohammad Shah Jahan ◽  
Md. Nazmul Hossain ◽  
Zunaira Anwar ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Stress Responses ◽  
Abiotic Stresses ◽  
Defense Mechanisms ◽  
Antioxidant Defense ◽  
Severe Drought ◽  
New Information ◽  
Effects Of Drought

In recent years, research on spermine (Spm) has turned up a lot of new information about this essential polyamine, especially as it is able to counteract damage from abiotic stresses. Spm has been shown to protect plants from a variety of environmental insults, but whether it can prevent the adverse effects of drought has not yet been reported. Drought stress increases endogenous Spm in plants and exogenous application of Spm improves the plants’ ability to tolerate drought stress. Spm’s role in enhancing antioxidant defense mechanisms, glyoxalase systems, methylglyoxal (MG) detoxification, and creating tolerance for drought-induced oxidative stress is well documented in plants. However, the influences of enzyme activity and osmoregulation on Spm biosynthesis and metabolism are variable. Spm interacts with other molecules like nitric oxide (NO) and phytohormones such as abscisic acid, salicylic acid, brassinosteroids, and ethylene, to coordinate the reactions necessary for developing drought tolerance. This review focuses on the role of Spm in plants under severe drought stress. We have proposed models to explain how Spm interacts with existing defense mechanisms in plants to improve drought tolerance.

HAS PSYCHOLOGIC MALNUTRITION TAKEN THE PLACE OF RICKETS AND SCURVY IN CONTEMPORARY PEDIATRIC PRACTICE?

PEDIATRICS ◽  
1963 ◽  
Vol 31 (6) ◽  
pp. 909-918
Author(s):  
Nathan B. Talbot
Keyword(s):  
Sixteenth Century ◽  
Lemon Juice ◽  
Climatic Conditions ◽  
Northern Europe ◽  
Scientific Medicine ◽  
Pediatric Practice ◽  
Therapeutic Value ◽  
High Prevalence ◽  
The Baltic

WHILE MEDICAL HISTORIANS cannot provide us with accurate statistics concerning the incidence of rickets and scurvy in centuries past, they leave little room for doubt about the high prevalence of these disorders prior to the advent of modern scientific medicine. Thus, Castiglione has written that in the sixteenth century scurvy raged throughout northern Europe, in Scandinavia, on the shores of the Baltic, and in the interior of Germany. It is interesting to note, however, that Jacques Cartier, whose sailors had been ravaged by scurvy, learned in 1536 from the Indians that the malady could be cured by juices of the almeda tree. This was 200 years before James Lind demonstrated the curative effects of lemon juice in his treatise on scurvy published in 1753 and almost 400 years before ascorbic acid, which was isolated by Szent-Gyorgi in 1928, was recognized to be vitamin C by Waugh and King in 1932. Rickets, likewise, was occurring in a large portion of children prior to the discovery of the existence of vitamin D by Hess, Steinbock, and Windaus in 1918, of its therapeutic value by Mellanby in 1919, of the equivalent role of sunlight by Hess in 1921, and of the chemical composition of the vitamins by Windaus in 1922. But 200 years earlier Friedrick Hoffman had the answer to the control of this disease almost in hand. He attached much importance to climatic conditions as a factor in rickets, noting that if anything is specially powerful in producing this affliction, it is a surrounding atmosphere of cold foggy air. He cited as striking evidence of this the famous emporium of England, London, which he found to be specially apt to produce and foster this disease.

On Approaches to Taking into Account the Risks of Changing Climatic Conditions when Planning and Implementing Oil and Gas Projects

2021 ◽  
Vol 18 (1) ◽  
pp. 52-65
Author(s):  
P. N. Mikheev
Keyword(s):  
Climate Change ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Climatic Conditions ◽  
Qualitative Assessment ◽  
Physical Factors ◽  
Gas Industry ◽  
Climate Risks ◽  
The Impact

The article discusses issues related to the impact of climate change on the objects of the oil and gas industry. The main trends in climate change on a global and regional (on the territory of Russian Federation) scale are outlined. Possible approaches to the identification and assessment of climate risks are discussed. The role of climatic risks as physical factors at various stages of development and implementation of oil and gas projects is shown. Based on the example of oil and gas facilities in the Tomsk region, a qualitative assessment of the level of potential risk from a weather and climatic perspective is given. Approaches to creating a risk management and adaptation system to climate change are presented.

scholarly journals Productivity of sorghum crops depending on agrotechnical methods of cultivation in the regions of the Russian Federation (review)

2021 ◽  
Vol 22 (2) ◽  
pp. 155-166
Author(s):  
O. P. Kibalnik ◽  
I. G. Efremova ◽  
Yu. V. Bochkareva ◽  
A. V. Prakhov ◽  
D. S. Semin
Keyword(s):  
Russian Federation ◽  
Plant Density ◽  
Climatic Conditions ◽  
Row Spacing ◽  
Early Maturing ◽  
Cultivation Technology ◽  
The Russian Federation ◽  
Area Unit ◽  
Growing Conditions

The review considers the unique diversity and versatility of the use of sorghum crops. The dependence of the yield of biomass and grain of varieties and hybrids of sorghum crops on the applied elements of the crop cultivation technology is analyzed: width of row spacing, density of standing plants in different zones of sorghum sowing in the Russian Federation. A variety of soil and climatic conditions of sorghum cultivation regions differ in the temperature regime, the reserves of soil moisture before sowing, the level of soil fertility, which determines the need to select the optimal elements of technology that ensure the achievement of the highest yield of varieties per unit area with the lowest material and technological costs. The analysis of the ways of placing plants on the own area also indicates the significant role of varietal biological features in increasing the sorghum yield, the purpose of sowing, and the level of field contamination. With limited resources of productive moisture for high-yielding sorghum varieties with a powerful habitus, wide-row sowing with row spacing of 70 cm and the density of standing plants 80-350 thousand per 1 ha, depending on the variety. Low-growing early-maturing thin-stemmed forms of grain sorghum should be sown in the usual ordinary row way with a row spacing of 15 or 30 cm with plant density of 500-600 thousand/ha. Sudan grass varieties that can withstand high density of standing plants (depending on agroclimatic conditions – up to 1.0-3.0 million per 1 ha) are cultivated using the technology of spiked cereals. As the result of the literature data analysis, the following trend has been revealed: the drier the growing conditions, the greater the requirements for choosing the optimal parameters of agrotechnical methods of cultivating sorghum crops aimed at the reducing the number of plants per area unit considering the specific character of the region of sorghum sowing.

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