Modeling infection and spread of Heterobasidion annosum in even-aged Fennoscandian conifer stands

2005 ◽  
Vol 35 (1) ◽  
pp. 74-84 ◽  
Author(s):  
Timo Pukkala ◽  
Timo Möykkynen ◽  
Magnus Thor ◽  
Jonas Rönnberg ◽  
Jan Stenlid
Keyword(s):  
Heterobasidion Annosum ◽  
Growth And Yield ◽  
Disease Dynamics ◽  
Severe Damage ◽  
Tree Roots ◽  
Growth And Survival ◽  
Coarse Root ◽  
Model Predictions ◽  
Disease Effect ◽  
The Impact

Heterobasidion annosum (Fr.) Bref. s. lato causes severe damage to forests. This study describes a model for simulating the infection and spread of Heterobasidion spp. in stands of Picea abies (L.) Karst. and Pinus sylvestris L. The model includes submodels for stand dynamics (plot simulation, growth and yield, and cross-cutting of trees) and disease dynamics: (i) spore infection, (ii) stump colonization, (iii) colonization of stump roots, (iv) vegetative transfer to tree roots, (v) spread of disease in tree roots, (vi) spread of decay in stems, and (vii) disease effect on tree growth and survival. To illustrate the model, a simulation was carried out on a Swedish Norway spruce stand where logging occurred during the high-risk season for spore infection. The model provides a means of incorporating the impact of root disease into forest planning. A change of parameters indicated that model predictions were sensitive to the spread rate and presence of initial disease centers. Further research is called for in areas related to the development of coarse root systems of various tree species and the probability and rate of transfer of disease from various sources of inoculum to healthy trees.

INFLUENCE OF GREENHOUSE SHADING AND DIFFERENT NUTRIENT MANAGEMENT PRACTICES ON ALLEVIATING HEAT STRESS, IMPROVING PLANT NUTRIENTS STATUS, FLOWERING GROWTH AND YIELD OF TOMATO

2020 ◽  
Vol 51 (4) ◽  
pp. 1001-1014
Author(s):  
Sulaiman & Sadiq
Keyword(s):  
Heat Stress ◽  
Management Practices ◽  
Nutrient Management ◽  
Block Design ◽  
Nutrient Status ◽  
Growth And Yield ◽  
Reproductive Growth ◽  
Positive Effects ◽  
Nutrition Programs ◽  
The Impact

The experiment was conducted in a greenhouse during 2017 and 2018 growing seasons to evaluate the impact of the shading and various nutrition programs on mitigating heat stress, reducing the use of chemical minerals, improving the reproductive growth and yield of tomato plant. Split-plot within Randomized Complete Block Design (RCBD) with three replications was conducted in this study. Shading factor was allocated in the main plots and the nutrition programs distributed randomly in the subplots. Results indicate that shading resulted in the decrease of daytime temperature by 5.7˚C as an average for both seasons; thus a significant increasing was found in leaf contents of macro nutrients (Nitrogen, Phosphorous, and Potassium), and micro nutrients (Iron, Zinc and Boron), except the Iron content in 2018 growing season. Furthermore, shading improved significantly the reproductive growth and tomato yield. Among the plant nutrition programs, the integrated nutrient management (INM) including the application of organic substances, bio inoculum of AMF and 50% of the recommended dose of chemical fertilizers; lead to the enhancement of nutrients content, reproductive characteristics and plant yield. Generally, combination of both shading and INM showed positive effects on plants nutrient status and persisting balance on tomato flowering growth and fruits yield.

scholarly journals The impact of multifactorial stress combination on plant growth and survival

2021 ◽  
Author(s):  
Sara I. Zandalinas ◽  
Soham Sengupta ◽  
Felix B. Fritschi ◽  
Rajeev K. Azad ◽  
Rachel Nechushtai ◽  
...  
Keyword(s):  
Plant Growth ◽  
Growth And Survival ◽  
The Impact

Deriving Tree Diameter Growth and Probability of Survival Equations from Successive Diameter Distributions

2008 ◽  
Vol 54 (1) ◽  
pp. 31-35
Author(s):  
Thomas G. Matney ◽  
Emily B. Schultz
Keyword(s):  
General Procedure ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Diameter Growth ◽  
Individual Tree ◽  
Statistical Probability ◽  
Growth And Survival ◽  
Tree Diameter ◽  
Growth And Yield Models ◽  
Diameter Distributions

Abstract Many growth and yield models have used statistical probability distributions to estimate the diameter distribution of a stand at any age. Equations for approximating individual tree diameter growth and survival probabilities from dbh can be derived from these models. A general procedure for determining the functions is discussed and illustrated using a loblolly pine spacing study. The results from the spacing study show that it is possible to define tree diameter growth and survival probability functions from diameter distributions with an accuracy sufficient to obtain a link between the individual tree and diameter growth and yield models.

The role of plant-parasitic nematodes in reducing yield of sugarcane in fine-textured soils in Queensland, Australia

2007 ◽  
Vol 47 (5) ◽  
pp. 620 ◽  
Author(s):  
B. L. Blair ◽  
G. R. Stirling
Keyword(s):  
Growth And Yield ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Lesion Nematode ◽  
Yield Responses ◽  
The Impact ◽  
Stalk Length ◽  
Plant Parasitic

Damage to sugarcane caused by root-knot nematode (Meloidogyne spp.) is well documented in infertile coarse-textured soils, but crop losses have never been assessed in the fine-textured soils on which more than 95% of Australia’s sugarcane is grown. The impact of nematodes in these more fertile soils was assessed by repeatedly applying nematicides (aldicarb and fenamiphos) to plant and ratoon crops in 16 fields, and measuring their effects on nematode populations, sugarcane growth and yield. In untreated plant crops, mid-season population densities of lesion nematode (Pratylenchus zeae), root-knot nematode (M. javanica), stunt nematode (Tylenchorhynchus annulatus), spiral nematode (Helicotylenchus dihystera) and stubby-root nematode (Paratrichodorus minor) averaged 1065, 214, 535, 217 and 103 nematodes/200 mL soil, respectively. Lower mean nematode population densities were recorded in the first ratoon, particularly for root-knot nematode. Nematicides reduced populations of lesion nematode by 66–99% in both plant and ratoon crops, but control of root-knot nematode was inconsistent, particularly in ratoons. Nematicide treatment had a greater impact on shoot and stalk length than on shoot and stalk number. The entire community of pest nematodes appeared to be contributing to lost productivity, but stalk length and final yield responses correlated most consistently with the number of lesion nematodes controlled. Fine roots in nematicide-treated plots were healthier and more numerous than in untreated plots, and this was indicative of the reduced impact of lesion nematode. Yield responses averaged 15.3% in plant crops and 11.6% in ratoons, indicating that nematodes are subtle but significant pests of sugarcane in fine-textured soils. On the basis of these results, plant-parasitic nematodes are conservatively estimated to cost the Australian sugar industry about AU$82 million/annum.

scholarly journals A fractional order mathematical model for COVID-19 dynamics with quarantine, isolation, and environmental viral load

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Mohammed A. Aba Oud ◽  
Aatif Ali ◽  
Hussam Alrabaiah ◽  
Saif Ullah ◽  
Muhammad Altaf Khan ◽  
...  
Keyword(s):  
Epidemic Model ◽  
Reproduction Number ◽  
Model Parameters ◽  
Disease Dynamics ◽  
Threshold Parameter ◽  
Fractional Model ◽  
Infected People ◽  
Fractional Models ◽  
Disease Epidemics ◽  
The Impact

AbstractCOVID-19 or coronavirus is a newly emerged infectious disease that started in Wuhan, China, in December 2019 and spread worldwide very quickly. Although the recovery rate is greater than the death rate, the COVID-19 infection is becoming very harmful for the human community and causing financial loses to their economy. No proper vaccine for this infection has been introduced in the market in order to treat the infected people. Various approaches have been implemented recently to study the dynamics of this novel infection. Mathematical models are one of the effective tools in this regard to understand the transmission patterns of COVID-19. In the present paper, we formulate a fractional epidemic model in the Caputo sense with the consideration of quarantine, isolation, and environmental impacts to examine the dynamics of the COVID-19 outbreak. The fractional models are quite useful for understanding better the disease epidemics as well as capture the memory and nonlocality effects. First, we construct the model in ordinary differential equations and further consider the Caputo operator to formulate its fractional derivative. We present some of the necessary mathematical analysis for the fractional model. Furthermore, the model is fitted to the reported cases in Pakistan, one of the epicenters of COVID-19 in Asia. The estimated value of the important threshold parameter of the model, known as the basic reproduction number, is evaluated theoretically and numerically. Based on the real fitted parameters, we obtained $\mathcal{R}_{0} \approx 1.50$ R 0 ≈ 1.50 . Finally, an efficient numerical scheme of Adams–Moulton type is used in order to simulate the fractional model. The impact of some of the key model parameters on the disease dynamics and its elimination are shown graphically for various values of noninteger order of the Caputo derivative. We conclude that the use of fractional epidemic model provides a better understanding and biologically more insights about the disease dynamics.

Impact of random soil properties on stress–strain response

2004 ◽  
Vol 41 (2) ◽  
pp. 351-355 ◽  
Author(s):  
Dieter Stolle ◽  
Peijun Guo ◽  
Gabriel Sedran
Keyword(s):  
Soil Properties ◽  
Constitutive Modelling ◽  
Soil Parameters ◽  
Strain Response ◽  
Constitutive Behaviour ◽  
Stress Strain ◽  
Deterministic Analysis ◽  
Model Predictions ◽  
Random Variability ◽  
The Impact

This paper analyzes the impact of natural random variation of soil properties on the constitutive modelling of geomaterial behaviour. A theoretical framework for accommodating variation in soil properties is presented. The framework is then used to examine the consequence of parameter variability on stress–strain relations. An important observation is that average soil parameters from a series of tests on small specimens, in which density of the specimens varies randomly, do not necessarily reflect the average constitutive behaviour of soil. Model predictions are shown to be consistent with the experimental data.Key words: random variability, deterministic analysis, soil parameters, constitutive model.

scholarly journals Effect of fungus Heterobasidion Annosum (FR) bref. on fir and spruce dying in the region of the NP "Durmitor" and "Biogradska gora"

2002 ◽  
pp. 49-58 ◽  
Author(s):  
Milosav Andjelic
Keyword(s):  
Infection Intensity ◽  
Heterobasidion Annosum ◽  
Parasitic Fungus ◽  
Anthropogenic Factors ◽  
Abiotic Factor ◽  
Forest Reserve ◽  
Virgin Forest ◽  
Long Period ◽  
The Past ◽  
The Impact

Several adverse factors of abiotic and biotic nature affect the vitality and decline of spruce and fir in the region of NP "Durmitor" and NP "Biogradska Gora". The most significant adverse abiotic factor is air pollution. Among the adverse biotic factors, the most significant is by all means the parasitic fungus Heterobasidion annosum. The damage caused by this fungus is especially severe in spruce and fir stands in the region of the NP "Durmitor". The infection intensity is approximately the same in both species. The damage caused by H. annosum is greater in the forests of NP "Durmitor", than in the forests of NP "Biogradska Gora". This can be explained by the fact that spruce and fir stands on Durmitor were felled without maintaining the forest order. In the virgin forest reserve NP "Biogradska Gora" in the past there were no fellings, i.e. the impact of anthropogenic factors was excluded. Fungus H. annosum cannot be eliminated form spruce and fir stands on Durmitor, but the treatment of stumps (immediately after the sanitation felling) with "Penofil" or "Borax" can check the velocity of its spread. In this way, the forest is given an opportunity to form more resistant populations through a long period by natural selection .

scholarly journals Pengaruh Magnesium, Boron, dan Pupuk Hayati terhadap Produktivitas Cabai serta Serangan Hama dan Penyakit (Effect of Magnesium, Boron, and Biofertilizers on Chili Pepper Productivity and Impact of Pests and Diseases)

2020 ◽  
Vol 30 (1) ◽  
pp. 65
Author(s):  
Wiwin Setiawati ◽  
Ahsol Hasyim ◽  
Bagus Kukuh Udiarto ◽  
Abdi Hudayya
Keyword(s):  
Yield Components ◽  
Growth Parameters ◽  
Block Design ◽  
Fruit Weight ◽  
Chili Pepper ◽  
Growth And Yield ◽  
Vegetable Crops ◽  
Positive Interaction ◽  
Pests And Diseases ◽  
The Impact

<p>Penggunaan pupuk hayati dan unsur hara makro sekunder seperti magnesium (Mg) dan hara mikro boron (B) diketahui dapat meningkatkan pertumbuhan, kualitas hasil tanaman, meningkatkan unsur hara dalam tanah serta mampu meningkatkan ketahanan tanaman terhadap serangan hama dan penyakit. Selain itu penggunaan pupuk tersebut dapat mengurangi kebutuhan terhadap pupuk kimia sintetis. Tujuan penelitian adalah mengetahui pengaruh aplikasi Mg, B, dan kombinasinya dengan pupuk hayati terhadap pertumbuhan dan hasil panen serta penekanan serangan hama dan penyakit. Penelitian dilakukan di Kebun Percobaan Balai Penelitian Tanaman Sayuran, Lembang, Jawa Barat (1.250 m dpl.) dari bulan Juni 2018 sampai bulan Februari 2019. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok terdiri atas delapan perlakuan dan empat ulangan. Perlakuan yang diuji adalah aplikasi Mg, B, dan kombinasi dengan pupuk hayati serta teknologi konvensional sebagai pembanding. Pengamatan dilakukan terhadap pertumbuhan tanaman (tinggi tanaman dan luas kanopi), komponen hasil dan hasil serta serangan hama dan penyakit penting yang menyerang tanaman cabai. Hasil penelitian menunjukkan bahwa kombinasi Mg, B, dan pupuk hayati yang diaplikasikan sebanyak dua kali pada umur 30 HST dan 45 HST mampu meningkatkan produktivitas cabai sebesar 21,68 ton/ha atau meningkat sebesar 54,53% dibandingkan dengan kontrol. Peningkatan produktivitas cabai terjadi karena adanya perbaikan dalam komponen hasil seperti jumlah bunga, jumlah buah, panjang, dan bobot buah serta adanya penekanan terhadap serangan hama dan penyakit seperti trips, antraknosa, lalat buah, dan penggerek buah sebesar 18,10% sampai 23,93%.</p><p><strong>Keywords</strong></p><p><em>Capsicum annuum</em>; Unsur hara makro; Pupuk hayati; Produktivitas; Organisme pengganggu tumbuhan</p><p><strong>Abstract</strong></p><p>The use of biofertilizer and macro and micro nutrients enhanced the growth and development, yield quality of vegetable crops as well as nutrient status of soil to a greater extent and to increased on pests and diseases resistance. Organic sources of nutrients including biofertilizers also economize the use of chemical fertilizers. The objectives of this study were to determine the best combination of Mg, B, and biofertilizer that increase the growth and yield of chili pepper and the impact to pest and diseases on chili pepper. The field experiment was conducted at the experimental field of the Indonesian Vegetable Research Institute, Lembang, West Java from June 2018 to February 2019. The experiment was arranged in a Randomized Block Design with eight treatments and four replicated. The treatments were Mg, B, and their combinations with biofertilizer compared to the conventional technologies as a control. The observations were carried out on the growth parameters (plant height and leaf canopy), yield components, pest and diseases of chili pepper. The results showed that the combinations of Mg, B, and biofertilizer increased the yield of chili up to 21.68 ton/ha or positive interaction beside beneficial agent with Mg, B, and biofertilizer package on 54.53%. Increased productivity of chili occurs because of improvements in yield components such as the number of flowers, number of fruits, fruit length and fruit weight and reduction of pest and disease attacks such as thrips, anthracnose, fruit flies and, fruit borers by 18.10% to 23.93%.</p>

scholarly journals Exploring the associations between transcript levels and fluxes in constraint-based models of metabolism

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Neeraj Sinha ◽  
Evert M. van Schothorst ◽  
Guido J. E. J. Hooiveld ◽  
Jaap Keijer ◽  
Vitor A. P. Martins dos Santos ◽  
...  
Keyword(s):  
Metabolic Flux ◽  
Transcript Levels ◽  
Proportionality Constant ◽  
Model Predictions ◽  
Physiological Information ◽  
Highly Expressed Genes ◽  
Transcriptomics Data ◽  
Genome Scale ◽  
The Impact ◽  
Constraint Based Models

Abstract Background Several computational methods have been developed that integrate transcriptomics data with genome-scale metabolic reconstructions to increase accuracy of inferences of intracellular metabolic flux distributions. Even though existing methods use transcript abundances as a proxy for enzyme activity, each method uses a different hypothesis and assumptions. Most methods implicitly assume a proportionality between transcript levels and flux through the corresponding function, although these proportionality constant(s) are often not explicitly mentioned nor discussed in any of the published methods. E-Flux is one such method and, in this algorithm, flux bounds are related to expression data, so that reactions associated with highly expressed genes are allowed to carry higher flux values. Results Here, we extended E-Flux and systematically evaluated the impact of an assumed proportionality constant on model predictions. We used data from published experiments with Escherichia coli and Saccharomyces cerevisiae and we compared the predictions of the algorithm to measured extracellular and intracellular fluxes. Conclusion We showed that detailed modelling using a proportionality constant can greatly impact the outcome of the analysis. This increases accuracy and allows for extraction of better physiological information.

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