Search

The existence of confining pressure is an important factor that can't be ignored in rock cutting process. Rocks show high strength and strong plasticity under confining pressure condition (CPC), leading to the low rock-breaking efficiency of drilling bit, which is more prominent in deep formation drilling. However, the understanding of rock-breaking mechanism of Polycrystalline Diamond Compact (PDC) cutter under CPC is still unclear. Given that fact, in this paper, a series of rock cutting experiments on sandstone and granite under different confining pressures and atmospheric pressure conditions were carried out using a self-made true triaxial rock cutting device. The cutting force, mechanical specific energy (MSE) and cuttings mass fraction under confining pressure and atmospheric pressure conditions were studied, and the cutting grooves were analyzed. The results show that the existence of confining pressure greatly increases the difficulty of rock cutting, which is embodied by the increase of cutting force and MSE. In addition, the size of cuttings produced under CPC is smaller, and the proportion of powdery cuttings increases with increasing confining pressure. Meanwhile, the cutting grooves obtained under CPCs are smoother. Microscopically, the existence of confining pressure greatly enhances the contact stress between PDC cutter and rock, resulting in a larger area of dense core when PDC cutter contacts with rock. Confining pressure leads to the difficulty of cuttings discharge to a certain extent, which easily results in the secondary and repeated destruction of cuttings and increases the energy dissipation. In general, confining pressure leads to the lower damage degree of PDC cutter to the rock, which makes the rock difficult to be drilled. The research results can provide some special guidance for rock breaking in deep formation, and provide practical thoughts and enlightenment for rock breaking, bits arrangement and optimization under CPC. Highlights: The cutting experiments under confining pressure condition are carried out by using the self-made rock cutting device that exerts three-dimensional stress on rock, which truly simulates the rock breaking process at the bottom of the well. The rock-breaking performances under atmospheric pressure condition and confining pressure conditions are comprehensively analyzed from the aspects of cuttings mass fraction, cuttings size, cutting groove and coarseness index. The rock-breaking mechanism of PDC cutter under confining pressure condition is investigated and the rock-breaking behavior of PDC cutter under confining pressure condition is studied. Three kinds of changing trends of mechanical specific energy with confining pressure are put forward, and the concept of confining pressure threshold is also proposed. [ABSTRACT FROM AUTHOR]

The relevance of this study is related to the need to form clear ideas about the factors involved in successful drilling operations and make a number of generalizations to existing methods for predicting the transport and cleaning of wells with a horizontal section, taking into account the features and patterns of the flow of drilling fluids in real drilling modes. The aim of this paper is to study the features of the spatial flow of a mixture of drilling fluid with solid particles in the coaxial and eccentric areas of the well; establish the patterns of the developing steady flow of the mixture through the well; and issue recommendations for applied calculations to improve the process of cleaning wells by using hydraulic methods. A well with a 12-meter horizontal eccentric section is chosen as the object of study, in which the flow is carried out in conditions that are as close as possible to actual drilling parameters. The methods of the mechanics of inhomogeneous continuums for viscous homogeneous and heterogeneous mixtures and computational fluid dynamics (CFD) combined with the ideas of a complex physical, mathematical, and numerical study of the internal flows of rheologically complex viscous media are the universal key to understanding the features and identifying the patterns of the processes considered in this study. It is established that particles can significantly affect the structure of the averaged and pulsating flow of a liquid droplet and their settling leads to the formation of an inhomogeneous anisotropic flow structure, the calculation of which requires modern two parameter turbulence models for Reynolds stresses. It is shown that in the bottom region of the annular space there is a zone with equivalent phase velocities, where the effects of a decrease in the intensity of molar transfer are manifested with an increase in the size of the sediment layer. The real drilling conditions are characterized by processes that accompany laminarization and stabilization of the mixture flow along the entire length of the well, and near the boundary of the fixed layer of settled particles, a narrow layer of their suspended state is formed. Moreover, the flow of particles of cuttings from the reservoir surface and their transition to a suspended state are mainly determined by convection-diffusion mechanisms, the intensity of the pulsating small-scale movement of vortices with an anisotropic structure, and the presence of local areas with moderately high flow velocities in contact with a curvilinear surface unstable to small disturbances of the section. The conditions for the formation of a stagnant zone in which sedimentation and growth in the size of deposits are intense are noted. In practice, a technology and algorithm for modeling the process of the interaction of two-phase flows with the walls of an eccentric pipe, based on demonstrations of CFD capabilities, is recommended. In addition, conclusions are made on improving the criterion relationships for determining the minimum flow rates of the drilling fluid, taking into account the correction of parameters characterizing the rheological features of the mixture, the intensity of turbulence, and the geometry of the annular space and connecting nodes. [ABSTRACT FROM AUTHOR]

Poplars establish on alluvial bars within sand and gravel-bed rivers. Alluvial bars also provide particularly suitable habitats for the proliferation of ants. We hypothesized that ants, by modifying substrate structure and resource availability in fluvial habitats, positively influence poplar growth during its establishment stage. We conducted a preliminary nine-month ex situ greenhouse experiment with one ant species (Lasius niger L.) and six different genotypes of poplar cuttings (Populus nigra L.), both collected on the Garonne River, SW France. Three main treatments: 'P. nigra alone', 'P. nigra without ants and with ant food' and 'P. nigra with ants and ant food' were applied. After one growing season, we tested differences in branching length and biomass of stems, roots and leaves. Certain genotypes showed significant differences in growth, but there were no significant differences in stem length, dry mass of stems and roots between the three treatments. The total biomass of poplars after the first growing season was positively affected by the initial size of the cuttings and was modulated by the genotype independently from the treatments. However, an increased poplar growth for the treatment without ants and with ant food was observed according to significant differences in dry weight of leaves and total biomass (i.e. dry mass of stems, roots and leaves) for the pooled genotypes across treatments. We discuss our results with the aim of serving as a reference for future in situ and ex situ experiments and field measurements exploring interactions between ants and poplars, specifically in riparian ecosystems. [ABSTRACT FROM AUTHOR]

The Cerrado biodiversity has been threatened by uncontrolled anthropization, which makes essential the propagation of native species for conservation purposes. This study aims to propagate Justicia lanstyakii, a Ni-accumulating subshrub, by cuttings, micropropagation, and plantlet formation. Hence, J. lanstyakii plants were collected in September (dry season) and December (rainy season). For cuttings, stem segments treated with IBA were inoculated in either sand or vermiculite. For in vitro propagation, the explants from mature plants were decontaminated with Carbendazim, ethanol, and either Na- or Ca-hypochlorite. Explant multiplication was accomplished in two consecutive subcultures in MS medium with BAP (0.0, 0.01 and 0.1 mg.L−1). Rooting was done with explants treated with IBA (0.0 and 0.01 mg.L−1) in MS. For J. lanstyakii plantlet formation, stem segments from seven distinct matrices were inoculated in ¼MS with BAP (1 and 2 mg.L−1). The results showed that the cuttings collected in December responded significantly better than those from September. Rooting and sprouting rates of December cuttings were 98.6% and produced 5.8 and 2.5 roots/shoots per explant, respectively. Furthermore, phytoregulators and substrates had no effects on cuttings. For in vitro propagation, Ca-hypochlorite showed higher explant decontamination and survival rates. Also, phytoregulators had no significant effects on multiplication and rooting. Nonetheless, the subcultures positively affected multiplication and rooting. However, plantlet development was highly influenced by the plant matrix and BAP (1 and 2 mg.L−1). Thus, all three techniques are suitable to propagate J. lanstyakii, which will facilitate its use in bioremediation programs of Ni-contaminated areas. [ABSTRACT FROM AUTHOR]

The paper presents research focused on behaviour of cement-bonded particleboards with modified composition during sudden changes of temperature and humidity. Four types of boards were made—one control and three modified ones. Finely ground limestone was used as a modifying component in binder. Secondary wood particles made from crushing cuttings of cement-bonded particleboards were used as chips substituent. Two sets of test specimens (1 set = 6 test specimens) were manufactured. The first set was stored in laboratory conditions. The second set was subjected to 10 cycles of sudden changes of temperature (− 20 °C to + 70 °C) and humidity in accordance with EN 321 (further in the paper referred to as "wet–frost–dry cycle".) After each cycle, dimensions and mass of the test specimens as well as ultrasonic pulse velocity were determined. A detailed analysis of structural changes in boards during cycling was carried out by an optical microscope. After 10 wet–frost–dry cycles were completed, bending strength and modulus of elasticity in bending were determined. The analysis of test results implies a very good relation between change of ultrasonic pulse velocity and width of cracks in the area of interfacial zone between cement matrix and wood particles. This finding also corresponds with dimensional and volumetric changes of the boards. Dependence of bending strength and modulus of elasticity in bending on composition of boards is apparent. Positive influence of secondary spruce chips on dimensional changes of cement-bonded particleboards caused by sudden changes of temperature and humidity was proved. Finely ground limestone contributes to more resistant structure of boards which leads to improved bending properties. Adverse conditions had more considerable influence on bending strength (decrease by 21% to 26%) than on modulus of elasticity in bending (decrease by 12% to 19%). [ABSTRACT FROM AUTHOR]

Sceletium tortuosum is a South African protected species with tremendous value in traditional and modern medicine. The plants' mesembrine-type alkaloids are potential therapeutics for a plethora of psychological, neurological and inflammatory disorders. In our in vitro and ex vivo studies, vegetative propagation and growth of this species were investigated. Cytokinin (CK) profiles were also explored. Shoot multiplication was induced on Murashige and Skoog (MS) medium supplemented with 2.5 µM indole-3-butyric acid (IBA). In vitro-generated shoots were inoculated on MS medium supplemented with 0, 2.5, 5.0 and 10.0 µM IBA or indole-3-acetic acid (IAA). Optimal rooting (55%), mean number of roots (3.80 ± 0.83) and new leaf pairs (4.65 ± 0.67) were achieved by 10.0 µM IBA. After greenhouse acclimatization, 45–90% of plantlets survived. All ex vivo shoot cuttings rooted well (90–100%). The highest mean number of roots (11.20 ± 1.37) and root length (57.18 ± 3.85 mm) were obtained by 5.0 µM IBA. Although spontaneous rooting was observed in both experiments, auxins enhanced multiple growth parameters. Cytokinin analyses of tissue-cultured (auxin-treated) and greenhouse (untreated) plants revealed higher cytokinin levels in vitro. These investigations provide rapid and efficient propagation techniques for Sceletium tortuosum which will be valuable to conservationists and pharmaceutical companies. Key message: Plant tissue culture and cuttings enabled rapid propagation of Sceletium tortuosum. Exogenous plant growth regulators were not essential for shoot multiplication, flowering and rooting. Auxins effectively improved growth parameters. [ABSTRACT FROM AUTHOR]

The effects of an inhibitor (Abz-E3M) of abscisic acid (ABA) 8′-hydroxylase, which is a primary enzyme of ABA catabolism, on dehydration tolerance and root formation in grape cuttings under drought conditions were investigated. Cuttings of 'Kyoho' grape (Vitis labrusca L. × Vitis vinifera L.) were sprayed with 100 μM of Abz-E3M and subjected to water deficit conditions at the stage when their first leaves fully expanded. The physiological and morphological changes in the leaves and basal portions of the cuttings were determined. In Abz-E3M-treated leaves, lower ABA metabolite and higher ABA and indole-3-acetic acid (IAA) concentrations were observed. Compared to the untreated control leaves, higher water potential was significantly maintained in Abz-E3M-treated leaves. Abz-E3M applications resulted in lower proline accumulation and 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity in the leaves and led to enhanced dehydration tolerance. In addition, the percentage of rooted cuttings was significantly increased by Abz-E3M application. In the basal portion of Abz-E3M-treated cuttings, endogenous IAA concentrations and the gene expressions of VvARF6 and VvARF8, which are positive regulators of adventitious root formation, were significantly increased. Moreover, the expression levels of the negative regulator, VvARF17, were significantly lower. These results suggested that the inhibition of ABA 8′-hydroxylase enhanced dehydration tolerance and adventitious rooting and may be an effective strategy for achieving drought stress tolerance in grape cuttings. [ABSTRACT FROM AUTHOR]

Willows plantations development could be an alternative for hydro-halomorphic soils but it is limited by combined stress salinity + hypoxia (main stressor under waterlogging conditions). We studied the effects of saline stress, alone or interacting with hypoxia, on growth, morphology and rooting process of six willows clones, assessing also whether rooting hormone (H, Indol Butyric Acid) contributes enhancing rooting under combined stress. Three hybrids of Salix matsudana × Salix alba (Sm×Sa), two of Salix babylonica × Salix alba (Sb×Sa) and a Salix nigra (Sn4) clone were evaluated in hydroponics. Ten treatments were generated combining salinity [moderate (MS): 5 dS/m, and high (HS): 10 dS/m]; hypoxia (with or without artificial aeration, HypO), and presence or absence of H. After 120 days, shoot and root biomass, root number and length, and hypertrophied lenticel number were evaluated. Contrary to what was expected, Sm×Sa and Sb×Sa hybrids showed no adverse additive effects of combined stress compared with saline stress; whereas in Sn4, S + HypO favored root biomass production increasing number and elongation of roots. Salinity was the main limiting factor for root production, being only MS conditions compatible with rooting, although limited. There was no common response in relation to H addition. In Sn4, H potentiated the effects of MS + HypO on root biomass, increasing number of roots. However, it had no positive effect on biomass production in the remaining hybrids, producing a higher root number but shorter in length. More effort is needed to understand the physiological mechanisms behind the response to combined stress in willows. [ABSTRACT FROM AUTHOR]

A transient mathematical model for modeling the transport of cuttings in the drilling mudflow during drilling horizontal and directional wells is presented. The model is based on a two-layer model that takes into account the cuttings in the fluid flow and the motionless cutting substrate. The relationships for calculating the mass exchange between the substrate and the cuttings in the flow, the friction and heat transfer between the cuttings and the fluid flow, as well as the heat transfer between the fluid and the substrate with the annulus. Options for simulating Newtonian and non-Newtonian fluid motion are implemented. It is assumed that the fluid moves in the annular channel formed by the well wall and the drill string. The presence of eccentricity in the channel is taken into account. To simulate the motion and heat transfer, a system of mass, momentum, and energy equations is solved for each component separately. The numerical implementation is based on the finite volume method, the convective terms are written in the counterflow form. The results of the test calculations demonstrating the efficiency of the model proposed are presented. The problem on the displacement of cuttings from an arbitrarily oriented well is considered. [ABSTRACT FROM AUTHOR]

The purpose of this research was to determine and evaluate the chemical properties of drilling waste from five well sites in Central and Eastern Poland. It was found that spent drilling fluids can contain high values of nickel and mercury (270 and 8.77 mg kg−1, respectively) and can exceed the maximum permissible limits recommended by the EC regulations for safety of soils (75 mg kg−1 for nickel and 1.5 mg kg−1 for mercury). The heavy metal concentrations in the studied drill cuttings did not exceed the maximum permissible limits recommended by the EC regulation. Drilling wastes contain macroelements (e.g., calcium, magnesium, and potassium) as well as trace elements (e.g., copper, iron, zinc, and manganese) that are essential for the plant growth. It was stated that water extracts of drilling fluids and drill cuttings, according to anions presence, had not any specific constituents of concern based on FAO irrigation guidelines, the USEPA WQC, and toxicity values. X-ray diffraction analysis was used to understand the structure and texture of waste drilling fluid solids and drill cuttings. Analysis of the mineralogical character of drilling fluid solids revealed that they contained calcite, quartz, muscovite, sylvite, barite, dolomite, and orthoclase. Drill cuttings contained calcite quartz, muscovite, barite, dolomite, and barium chloride. [ABSTRACT FROM AUTHOR]

Biomass from forestry is one of the largest components of Sweden’s renewable resources. Poplars are currently the highest producing tree species available and are therefore natural choices for biomass-oriented production. Growing poplars has been of most interest on agricultural land, but the knowledge and experience about their cultivation is still limited. Factors that have a large impact on the regeneration results are plant material, competing vegetation, browsing and damage caused by voles or climatic factors. Due to large establishment costs, there is a need to find methods to secure the establishment both biologically and economically. In this study the effect of plastic mulch in combination with three different plant types (short cuttings, long cuttings and rooted plants) were tested at three different sites. Five years after planting, the overall effect of mulch was an improved plant survival and growth. In most cases, long cuttings outperformed short cuttings and rooted plants. Clonal differences were present, indicating the importance of using plant material adapted to site conditions. All sites were heavily affected by browsing and during the experimental period 100% of the plants were damaged at some point. Planting poplars without fencing is therefore doubtful. Results from this study conclude that poplars can be established with success on agricultural land if proper measures are used depending on the site to be planted. [ABSTRACT FROM AUTHOR]

Developing methods for routine clonal propagation of sandalwood (Santalum austrocaledonicum) is important for its domestication and development as a commercial agroforestry species. The amenability of this species to propagation by leafy stem cuttings in low-cost non-mist propagators was assessed in four separate experiments. These experiments evaluated the effects of (1) genotype (15 genotypes from two island provenances), (2) cutting position on the stock plant (apical, medial and basal), (3) cutting size (1-node/400 mm2 and 2-node/800 mm2 leaf area), (4) three propagation media [scoria (5 mm, air-filled porosity (AFP)—29%), vermiculite and perlite (1:1 v/v, AFP—46%) and vermiculite, perlite and peat (2:2:1 v/v/v, AFP—42%)], (5) indole-3-butyric (IBA) (3000, 4000 and 8000 ppm) and (6) irradiance in the propagator [daily light integral (DLI) 5.3, 3.9, 2.6, 2.2 mol m−2 day−1]. IBA, propagation media and cutting size had no significant effect on rooting percentage, root number or root growth. Evidence of provenance-based variation in rooting capacity was recorded with greater rooting success for genotypes from the island of Erromango compared with Tanna. Variation in adventitious root induction was also recorded between individual genotypes from Erromango across all four experiments. Cuttings collected from the apical and medial parts of the shoot on the stock plant had higher rooting percentage than those collected from the base. Differences in rooting capacity between apical and medial shoots were variable between experiments and may be attributed to different levels of hardening. The use of artificial shade (~ 70%) to achieve a mean DLI of between 2.6 and 3.9 mol m−2 day−1 increased rooting percentage compared to both lower (2.2 mol m−2 day−1 or ~ 90% shade) and higher (5.3 mol m−2 day−1 or ~ 50% shade) irradiance treatments. Leaf retention of cuttings in the propagator was positively associated with the percentage of cuttings with adventitious roots, with highest percentage in cuttings with full leaf retention, regardless of original cutting size. This study demonstrated S. austrocaledonicum seedlings can be successfully propagated by cuttings provided the propagation conditions are optimized for each genotype. [ABSTRACT FROM AUTHOR]

The performance of gas-drilling (drilling oil and gas wells with air, nitrogen, or natural gas) is very unpredictable in many areas due to lack of proper design of drilling parameters because of limited understanding of gas-rock interaction which requires knowledge of heat transfer in the well system. Complete analysis of rock failure requires an accurate mathematical model to predict gas temperature at the bottom hole. The currently available mathematical models are unsuitable for use for the purpose because they do not consider the effects of formation fluid influx, Joule-Thomson cooling, and entrained drill cuttings. A new analytical solution for predicting gas temperature profiles inside the drill string and in the annulus was derived in this study for gas-drilling, considering all these three effects. Results of sensitivity analyses show that formation fluid influx can significantly increase the temperature profiles in both the drill string and the annulus. The Joule-Thomson cooling effect lowers the temperature in the annulus only in a short interval near the bottom hole. The drill cuttings entrained at the bottom hole can slightly increase the temperature profile in the annulus. [ABSTRACT FROM AUTHOR]

High-quality black walnut ( Juglans nigra L.) logs are of great economic value and are used in the manufacture of high-end products. Indigenous to the central hardwood region, black walnut has been commercially cultivated for many years, and genetic improvement and selections have resulted in superior timber genotypes. The recalcitrance of black walnut cuttings to form adventitious roots is the greatest hurdle for mass propagation of improved material. The goal of this research was to improve the frequency of adventitious root formation in black walnut cuttings, and investigate anatomical changes during root development. Softwood cuttings (15-20 cm) were collected from juvenile and mature sources of elite genotypes, dipped for 60 s in 31.1, 62.2, or 93.2 mM indole-3-butyric acid-potassium salt (K-IBA), or 36.9, 73.8, or 110.7 mM indole-3-butyric acid (IBA), and then inserted into a moist medium consisting of 3 perlite: 1 coarse vermiculite (v/v). Cuttings were placed in bench-top fog chambers or a mist bench for 5 weeks. To visualize anatomical changes during root formation, stems were fixed in formaldehyde, embedded in paraffin, serially sectioned, and stained on sequential days throughout root development. Rooting was greatest (72%) for cuttings exposed to 93.2 mM K-IBA and placed in the fog chamber, while cuttings treated with IBA rooted at lower frequencies (16-22.2%). Cuttings in the mist bench often deteriorated and rooted at lower frequencies independent of the auxin type. Anatomical analysis revealed adventitious root initials by day 16 and root primordia formation by day 18. Rooted cuttings survived acclimatization to the greenhouse. [ABSTRACT FROM AUTHOR]

Southern pine genetic improvement programs have selected for faster early growth which has often increased yields over unimproved material, and some of this improvement is likely attributable to variation in growth phenology among genotypes. However, the genetics of shoot growth phenology traits are not well characterized. Loblolly pine cuttings and seedlings from parents originating in the Atlantic coastal plain (ACP) and Florida and grown on sites established in Palatka, FL and Cuthbert, GA were assessed for shoot phenology and growth traits during the second year and for growth in year 6. Individual-tree clonal repeatability in different growth and shoot phenology traits varied from 0.09 to 0.79 in cuttings, and was lower in Palatka than Cuthbert. Non-additive components of heritability were lower, with a few exceptions, than additive effects. Additive and genotypic correlations across sites were high (>0.6) for all traits measured in cuttings and for most seedling traits, suggesting low genotype × environment interactions between these two sites. Compared with progeny from crosses between ACP parents, progeny of Florida parents started growth earlier in the season and ended later. Strong genetic correlations were observed between second-year phenology traits and sixth-year height and diameter. This suggests some two-year traits could be useful for early selection of high-performing genotypes. [ABSTRACT FROM AUTHOR]

Jatropha curcas microshoots excised from well-established multiple shoot cultures of CSMCRI-1 were used as microscions. Different age microscion (6 to18-month-old shoots) and rootstock (15 to 90-day-old) were used for grafting. Among all the different combinations, 18-month-old scions and 60-day-old rootstocks developed grafts with 58.4 % success rate. The grafting efficiency was further increased by treating scion and rootstock with 0.05 mg/L BAP (6-benzylaminopurine) and 0.05 mg/L ZN (zeatin). BAP treated scion grafted on 60 days old seedlings established early union. Graft union was dressed with tissue paper wetted with 0.1 % Carbemedozo and Macrinite (CM-75) and 400 mg/L amoxicillin-clavulanic acid for infection free graft. Dressing significantly increased the rate of survival (97 %) of the grafted plants. 97 % microshoots were successfully rooted via grafting. Grafting altered the plant architecture and made them dwarf. The net photosynthetic rate of grafted plants was higher than non-grafted plants. The seed yield of grafted plants was significantly higher than cuttings and seedling. [ABSTRACT FROM AUTHOR]

To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora ( Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha. Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed. [ABSTRACT FROM AUTHOR]

The interest for fast growing poplar species has increased, but the establishment on forest soils can be disappointing. One explanation could be low pH-levels. Thus, the main purpose of this study was to test the development of available poplar clones on soils with different soil acidity. The study was divided into two parts. In study A, poplar cuttings were planted in peat soil with pH-levels ranging from 3.4 to 5.7. In study B, the same plant material was planted in forest soils collected from different sites with different pH levels. Both studies were carried out in a greenhouse. Soil acidity had a significant effect on plant development. With increasing pH, height and biomass of the poplar clones increased. A difference in allocation between root and aboveground biomass was seen among treatments with more biomass directed above ground at higher pH. This pattern was more pronounced with increasing plant weight. Less Al and more Ca were found in leaves from plants grown in soils with higher pH, but P was low overall in the forest soil. Results from this study show that low pH-values can hamper the establishment of poplar. The availability of Ca, P and Al is also of importance, since they could counteract or increase the adverse effects of low pH-levels. [ABSTRACT FROM AUTHOR]

Low amenability of the eucalypt, Corymbia torelliana × C. citriodora, to vegetative propagation has limited its establishment in plantations. This study determined whether rooting capacity and cutting vigour varied along the central shoot of Corymbia seedlings, and whether these differences are related to stem development and hormone concentrations. Dual-node cuttings were harvested from five positions (nodes 1/2, 3/4, 5/6, 7/8 and 9/10) along the seedling shoot (S1), and cuttings were treated with one of four levels of indole-3-butyric acid (IBA). Root formation, root and shoot growth, stem anatomy, and the concentrations of indole-3-acetic (IAA) and abscisic acid (ABA) were assessed at each shoot position. The central node of the rooted cuttings was harvested for fresh cuttings to observe whether maturation emerged in ramets (S2) from the different ortet positions. Rooting and vigour were highest from the most-apical seedling nodes (7/8 and 9/10 in S1), which had less lignification and sclerenchyma development than more-basal nodes (1/2, 3/4 and 5/6). IAA and ABA concentrations differed little between the seedling nodes. In contrast, cuttings from the ramets (in S2) had similar rooting, vigour, lignification and sclerification to each other, but there were large differences in IAA and ABA concentrations depending on their previous point-of-origin in the seedling. High doses of IBA reduced rooting. Rooting and vigour were related to lignification and sclerenchyma development rather than IAA or ABA concentrations. Mass vegetative propagation of C. torelliana × C. citriodora is achievable because mean rooting percentages in S1 and S2 were 61 and 68 %, respectively, using cuttings from small seedling ortets and their ramets. [ABSTRACT FROM AUTHOR]

With global warming, an advance in spring leaf phenology has been reported worldwide. However, it is difficult to forecast phenology for a given species, due to a lack of knowledge about chilling requirements. We quantified chilling and heat requirements for leaf unfolding in two European tree species and investigated their relative contributions to phenological variations between and within populations. We used an extensive database containing information about the leaf phenology of 14 oak and 10 beech populations monitored over elevation gradients since 2005. In parallel, we studied the various bud dormancy phases, in controlled conditions, by regularly sampling low- and high-elevation populations during fall and winter. Oak was 2.3 times more sensitive to temperature for leaf unfolding over the elevation gradient and had a lower chilling requirement for dormancy release than beech. We found that chilling is currently insufficient for the full release of dormancy, for both species, at the lowest elevations in the area studied. Genetic variation in leaf unfolding timing between and within oak populations was probably due to differences in heat requirement rather than differences in chilling requirement. Our results demonstrate the importance of chilling for leaf unfolding in forest trees and indicate that the advance in leaf unfolding phenology with increasing temperature will probably be less pronounced than forecasted. This highlights the urgent need to determine experimentally the interactions between chilling and heat requirements in forest tree species, to improve our understanding and modeling of changes in phenological timing under global warming. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the role of endogenous polyamines (PAs) (the sum of free plus soluble conjugate plus insoluble bound) on rooting potential of leafy cuttings of an easy, that is,'Arbequina' and a difficult-to-root olive cultivar, that is, 'Kalamata'. Subsamples of cuttings were taken for PAs analysis before planting in the mist system and during the early phases of rhizogenesis (EPR). 'Arbequina' exhibited higher initial free and total PA content than 'Kalamata'. Spermidine (Spd) was the predominant PA observed in both cultivars. A low content of free putrescine (Put) and Spd was found in both cultivars, whereas spermine (Spm) was occasionally detected. 'Arbequina' as well as 'Kalamata' exhibited the highest free Put and free Spd in summer and Put was the predominant PA among the free PAs. 'Arbequina' exhibited the highest individual and total PAs in spring, followed by those in summer and autumn. In contrast, 'Kalamata' had the maximum PAs in summer and the lowest in autumn. Changes in the endogenous content of individual and total PAs during the EPR were also observed. Treatment of 'Kalamata' cuttings in autumn with both indole-3-butyric acid (IBA) and Put increased rooting compared to IBA alone. Among the PAs administered, Put was the most effective, whereas Spd and Spm failed to promote rooting. PAs, especially in their free form, seem to be involved in the rooting process of olive cuttings; Put application enhanced the rooting response of the difficult-to-root 'Kalamata' olive cultivar. [ABSTRACT FROM AUTHOR]

Several techniques have been developed for reinvigorating, rejuvenating or maintaining the juvenility of plants. None of these techniques is as effective as natural rejuvenation whereby the most mature plant parts, the reproductive organs, produce the most juvenile plant parts, the embryos, through gametogenesis and sexual reproduction. The most common criteria for identifying reinvigoration or rejuvenation are based on morphology, morphogenic capacity and the ability to produce cones or flowers. Doubts remain over whether true rejuvenation (reduced ontogenetic age) can be achieved by artificial methods such as serial vegetative propagation, or whether these methods merely provide reinvigoration (reduced physiological age) by temporarily removing environmental and physiological constraints to growth. Rejuvenation and reinvigoration are difficult to distinguish from each other but there is some evidence that artificial methods provide at least partial rejuvenation of plants. This review examines methods for delaying the maturation of juvenile plants and for reducing the ontogenetic or physiological age of more-mature plants. The review discusses theoretical and practical aspects of juvenility, rejuvenation and reinvigoration in clonal forestry, and identifies research areas in maturation that could lead to more-effective methods for establishing high-productivity plantations. [ABSTRACT FROM AUTHOR]

This paper discusses a new procedure for calculating the conductivity and volumetric heat capacity of drill cuttings from boreholes, an important factor when designing shallow geothermal systems. The experiment in question consists of placing 55-65 kg drill cutting samples inside a container, along with a heat source (point source assumed), and arranging temperature sensors, connected to a data logger, at known distances from the source. A mathematical method for determining the conductivity and volumetric heat capacity associated with this experiment is described. [ABSTRACT FROM AUTHOR]

Given a range space $(X,\mathcal{R})$, where $\mathcal{R}\subset2^{X}$, the hitting set problem is to find a smallest-cardinality subset H⊆ X that intersects each set in $\mathcal{R}$. We present near-linear-time approximation algorithms for the hitting set problem in the following geometric settings: (i) $\mathcal{R}$ is a set of planar regions with small union complexity. (ii) $\mathcal{R}$ is a set of axis-parallel d-dimensional boxes in ℝ. In both cases X is either the entire ℝ, or a finite set of points in ℝ. The approximation factors yielded by the algorithm are small; they are either the same as, or within very small factors off the best factors known to be computable in polynomial time. [ABSTRACT FROM AUTHOR]

In conifers, vegetative propagation of superior genotypes is the most direct means for making large genetic gains, because it allows a large proportion of genetic diversity to be captured in a single cycle of selection. There are two aims of vegetative propagation, namely large-scale multiplication of select genotypes and production of large numbers of plants from scarce and costly seed that originates from controlled seed orchard pollinations. This can be achieved, in some species, either through rooted cuttings or rooted microshoots, the latter regenerated through tissue culture in vitro. Thus far, both strategies have been used but often achieved limited success mainly because of difficult and inefficient rooting process. In this overview of technology, we focus on the progress in defining the physical and chemical factors that help the conifer cuttings and microshoots to develop adventitious roots. These factors include plant growth regulators, carbohydrates, light quality, temperature and rooting substrates/media as major variables for development of reliable adventitious rooting protocols for different conifer species. [ABSTRACT FROM AUTHOR]

Root morphology of 5-year-old trees of Dacryodes edulis (G. Don) H. J. Lam of seed and two vegetative (cutting and marcot) origins were assessed in Cameroon. Roots of D. edulis trees of seed and vegetative origins were totally excavated and their root morphology described and quantified. Trees of seed origin were characterized by a tap root, reaching depths of about 1.2 m. Contrarily trees of cutting origin showed three strong vertical roots ( d > 5 mm) with the longest reaching depths of 1.31 m. Trees of marcot origin were observed to have thick, relatively short prominent vertical roots, reaching depths of 1.15 m. At fixed lateral intra-row distances of 50 cm from tree bases, trees of seed and marcot origins recorded high root densities at soil depths of 0–20 cm; both differed significantly ( p = 0.032) from those of trees of cutting origin. At soil depth of 60–100 cm, trees of cutting origin recorded the highest root density which however differ significantly ( p = 0.016) from those of trees of both seed and marcot origins. D. edulis trees of seed origin had a tap root system, whereas trees of vegetative origin (cuttings and marcots) had developed prominent main adventitious roots growing vertically (sinker roots), into greater depths and a wider/deeper lateral root spread than seedlings. This could be a vital adaptation to the absence of a genetically determined tap roots in trees of vegetative origins so as not to compromise the acquisition of soil-based resources (water and dissolved ions) and anchorage. [ABSTRACT FROM AUTHOR]

Time to first root in cuttings varies under different environmental conditions and understanding these differences is critical for optimizing propagation of commercial forestry species. Temperature environment (15, 25, 30 or 35 ± 2°C) had no effect on the cellular stages in root formation of the Slash X Caribbean Pine hybrid over 16 weeks as determined by histology. Initially callus cells formed in the cortex, then tracheids developed and formed primordia leading to external roots. However, speed of development followed a growth curve with the fastest development occurring at 25°C and slowest at 15°C with rooting percentages at week 12 of 80 and 0% respectively. Cutting survival was good in the three cooler temperature regimes ([80%) but reduced to 59% at 35°C. Root formation appeared to be dependant on the initiation of tracheids because all un-rooted cuttings had callus tissue but no tracheids, irrespective of temperature treatment and clone. [ABSTRACT FROM AUTHOR]

We studied the effects of ethylene, (Z)-hexen-3-al, combinations of ethylene and (Z)-hexen-3-al, methyl jasmonate on the release of terpenoids and green leaf volatiles (GLVs) of Populus simonii × P. pyramidalis ‘Opera 8277’ by fumigation. The results show that exposure to ethylene alone did not induce volatiles. However, it was induced by exposure to combinations of (Z)-hexen-3-al and ethylene, a large amount of hexenal and hexen-3-ol as compared to sole (Z)-hexen-3-al exposure, which indicated that the release of wounding signals of P. simonii × P. pyramidalis ‘Opera 8277’ could be synergized by ethylene and (Z)-hexen-3-al. [ABSTRACT FROM AUTHOR]

The present study investigates optimal conditions for the vegetative propagation of Himalayan yew Taxus wallichiana Zucc., an important medicinal tree, during spring. Effect of four treatments: (a) sex of donor plant (male and female), (b) age/type of shoot (1, 2, 3 year old, long and dwarf shoots), (c) auxin treatment (IBA and NAA at 0, 0.5, 1.25, 5.0 & 50.0 mM) and (d) rooting environment (raised beds/polythene bags) on percentage rooting in stem cuttings was studied. Randomized complete block (RBD) designs were used for experimentation. Rooting ability of cuttings was significantly influenced by all these treatments. The overall rooting response was higher in long shoot cuttings taken from female tree. Age of shoot also influenced the rooting response and was highest in 1 year old long shoot cuttings of female tree. Exogenous application of auxin, α-naphthalene acetic acid (NAA) and indole-3 butyric acid (IBA), had significant positive effect on the percentage rooting. IBA significantly enhanced the rooting percentage in 1 year old long and dwarf shoots at lower doses and 2 and 3 year old long shoots from female tree at higher doses. Maximum percent rooting (90% ± 2.8) was obtained with interactive effect of 0.5 mM, NAA (22 h) × 1 year old long shoot from female tree; followed by the interactive effect of 50 mM IBA (5 s) × 3 year old long shoot from female tree (83% ± 4.1). Cuttings planted in soil: sand medium in polythene bags showed earlier rooting response (12 weeks) than cuttings planted in raised nursery beds (24 weeks). Overall, the findings of this study suggest that 0.5 mM IBA treatment is suitable for enhancing adventitious rooting in 1 year old long and dwarf shoots of male and female trees. IBA at higher doses is suitable for enhancing the rooting percentage of 2 and 3 year old long shoots from female tree. This study provides a significant lead towards the development of a simple and inexpensive technique for large scale propagation, a forestation of elite genotypes and raising of bush type plantation under ex-situ conditions. [ABSTRACT FROM AUTHOR]

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30–50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10–30 cm2 leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting. [ABSTRACT FROM AUTHOR]

A study was conducted on the twelve clones of shisham (Dalbergia sissoo Roxb.). These clones were obtained from India and Nepal. Single-node leafy cuttings were prepared from the vegetative multiplication garden to examine the clonal variation, effect of IBA treatment on rooting response and associated metabolic changes during adventitious root formation. A remarkable and significant variation was observed due to treatment of 2,000 ppm IBA in the rooting parameters. Clonal variations were also significant for root and shoot growth while length of root was insignificant. Among the twelve clones studied; C3 (Tulsipur, Gonda, Uttar Pradesh, India) and C4 (Laxmipur, Gonda, Uttar Pradesh, India) clone cuttings have given the highest rooting response. Interaction (clone × IBA) was significant only for production of number of roots per cutting. Periodic sampling for clone C3 was performed at 0, 7, 14, 21, 28 and 35 days to examine the contents of total soluble sugars, starch, protein and peroxidase (PER) activity in the rooting zone of cuttings (∼0.5 cm) during adventitious root primordium development. A significant increase in all the metabolic activities was noted due to IBA. Total soluble sugars and starch contents of cuttings decreased with the passage of time. Protein content and PERactivity started to increase in the early stage and reached the highest level on day 21, followed by a decline at the 35th day of sampling. These trends were common for both IBA treated and untreated cuttings. Protein content and PER-activity remained higher in the rooting zone of IBA treated cuttings. Overall these findings suggested that exogenous application of IBA may have activated carbohydrate metabolism for release of energy, while protein and PER-activity were necessary for cell division and differentiation during adventitious root primordium initiation and development in the rooting zone of cuttings. [ABSTRACT FROM AUTHOR]

The main objective of our clonal propagation program is the production of high quality timber and faster tree growth. Teak (Tectona grandis Linn. f.) is an important plantation species in the tropics but the demand of teak timber is increasing globally. Teak planting stock is still produced from seeds of unselected elite genotypes which may lead to poor stand establishment. The number of seeds per fruit and their germination ability are also variable and limited by several factors. Therefore an alternative method i.e., clonal propagation is required for mass multiplication of elite trees. It is an established fact that the clonal propagation or adventitious root formation in cuttings is markedly affected by several external and internal factors. Considering these, an experiment was conducted on leafy soft wood shoot cuttings of 3-year-old hedged teak stock plants grown in a hedge garden to study the effects of branch position and auxin treatment on adventitious root formation. A factorial completely randomized design was used for experimentation. Coppice shoots were collected from basal, middle and upper positions of the hedge garden; and mono-nodal leafy cuttings were prepared. These cuttings were treated with different concentrations of IBA and NAA; and were cultured in a mist chamber for rooting where the relative humidity was maintained at 85 ± 2% with maximum and minimum day-night temperature at 32 ± 1°C and 26 ± 1°C respectively. After 45 days the cuttings were removed from the rooting medium and observations were made. It was observed that the rooting parameters viz., percent rooting and percent sprouting, mean number of leaves, mean number of shoots and length, and mean number of roots and length per cutting were significantly influenced by the branch position and auxin treatment. Treatment with 4000 ppm IBA increased percent rooting and percent sprouting whereas NAA suppressed it. Treatment with 4000 ppm IBA also increased the mean number of leaves and shoots, and the length, and the mean number of roots per cutting. The highest mean number of roots and length were observed in cuttings taken from the branch emerging at the upper position followed by branches of middle and lower position. Cuttings of branches at a middle position showed the highest values of percent rooting, percent sprouting, mean number of leaves and shoots and mean shoot length per cutting. Furthermore, the interactive effect of branch position and auxin treatment on rooting and sprouting response was also found to be significant. Overall, the findings of this investigation suggest that middle branch position in hedge plants and 4000 ppm IBA can be made to induce maximum rooting and to produce high quality planting stock material for clonal forestry program of teak. [ABSTRACT FROM AUTHOR]

Aging of the donor tree decreased adventitious root formation in shoot cuttings of Tectona grandis Linn. f. (teak). Exogenous application of auxins, i.e., a-naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA) has a significant positive effect on the percentage of rooting. The maximum percent rooting was obtained with 4,000 ppm IBA as compared to other treatment. Significant increase in root number was recorded in shoot cuttings treated with 4,000 ppm NAA. The overall rooting response was better in the treatment with IBA rather than with NAA. Further periodic samples (0, 10, 20, and 30 days) were taken to assess the total soluble sugar, starch, protein, and peroxidase (PER) activity in the rooting zone of shoot cuttings of teak during adventitious root formation. Application NAA and IBA to shoot cuttings resulted in an increase in the level of total soluble sugar, starch, protein, and PER-activity in the rooting zone. The stored carbohydrates were utilized during adventitious root formation. Hence, total soluble sugar and starch contents of cuttings, irrespective of age of donor plants, decreased with the passage of time in cuttings planted for rooting. Significant fluctuations were observed in the protein content of cuttings during the time of root induction. There was an increase in the protein content with the passage of time from the day of planting up to its 20th day, followed by a sharp decline in the protein content of cuttings at the 30th day of planting, irrespective of the age of donor plants or the treatment of cuttings with auxins. Irrespective of donor plant age, PER-activity in the cuttings increased from the day of their planting for rooting up to the 20th day, and then declined at its 30th day of planting. It was interesting to note that PER-activity remained higher at all stages in the cuttings of 2-month-old seedlings which rooted profusely as compared to the cuttings of 15- and 30-year-old donor plants those rooted poorly. This study suggested that the exogenously applied NAA and IBA at different concentration seems to activate sugar metabolism for release of energy, protein and PER-activity which are necessary for cellular division and differentiation during adventitious root primordium initiation or development in the rooting zone of shoot cuttings. [ABSTRACT FROM AUTHOR]

Shoot anatomical features viz., number of vessel elements, width and length of vessel and fibre elements were studied in relation to juvenility/maturity of teak (Tectona grandis Linn. f.). The findings show significant differences in these features, which indicates that variation in shoot anatomy can be used as a reliable indicator of juvenility/maturity in teak. The effect of age of donor plants and application of auxins on adventitious root formation in single noded leafy stem cuttings of teak was also investigated. Aging of donor trees suppressed rooting and sprouting of cuttings, but increased callus formation at the base of cuttings. Per cent rooting and per cent sprouting in cuttings decreased as age of donor plants increased from 2-months to 15-years and up to 30-years. IBA treatment promoted per cent rooting as well as per cent sprouting, NAA promoted only rooting and it suppressed sprouting. The effect of auxin treatment on rooting and sprouting of teak stem cuttings varied with the age of donor plants. Auxin and its concentration, which suppressed rooting and sprouting in cuttings of younger donor plants, actually promoted rooting when cuttings were taken from more mature donor plants. It appears that the auxin requirement for causing and promoting rooting in teak cuttings increased with increasing age of donor plants. The higher auxin requirement for causing and promoting rooting in cuttings of older trees may be due to a decrease in the content on endogenous auxins or decreased sensitivity of aging tissues to rooting promoters and /or accumulation of inhibitory substances which inhibit rooting. [ABSTRACT FROM AUTHOR]

In order to improve vegetative propagation of a difficult to root Cotinus coggygria the stock plants were subjected to: etiolation, shading and spraying with IBA, combined with the application of two commercially available rooting powders. The IBA treatment was more suitable for rooting of C. coggygria cuttings than the NAA application and it enhanced rhizogenesis regardless of the form of auxin application (foliar application to a stock plant or a rooting powder used directly on cuttings) and the amount of light provided to stock plants. Etiolation did not improve rhizogenesis in stem cuttings, however, reduction of light intensity by 50% and 96% of the ambient prior to harvest of cuttings affected rooting positively. Positive effects of shading can be ascribed to changes in shoot anatomy, i.e. a weaker sclerenchyma development. Synergistic effect of shading and foliar auxin application can result from the increase in leaf blade area and/or thinner lower epiderm. Enhanced rooting in cuttings from shoots grown out under reduced light intensity was accompanied by decrease in the contents of total soluble sugars, soluble proteins and free ABA and by increase in total chlorophyll, free amino acids, polyphenolic acids and free IAA contents. [ABSTRACT FROM AUTHOR]

Increased levels of ethylene in plants are responsible for many deleterious effects such as early senescence, fruit deterioration and inhibition of root elongation. Several cyclopropene derivatives have previously been studied as inhibitors of ethylene action in plants. This study focuses on one such compound, 1-cyclopropenylmethyl butyl ether and its effect on the growth of roots and shoots of canola plants as well as rooting of mung bean seedlings. 1-cyclopropenylmethyl butyl ether increased root length in canola plants, but had no significant effect on shoot length. In rooting studies, mung bean seedlings treated with 1-cyclopropenylmethyl butyl ether prior to root excision had fewer numbers of roots than control plants that were not treated with the ethylene action inhibitor. The same rooting study, when repeated in the presence of 1-aminocyclopropane-l-carboxylic acid (ACC), demonstrated an overall increase in the number of roots of inhibitor-treated and non-treated plants, however, the inhibitor was still effective in decreasing the number of roots, compared to its non-treated counterpart. [ABSTRACT FROM AUTHOR]

Several plant baits were tested to quantify Rhizoctonia inoculum density in Eucalyptus clonal garden soils. Experiments carried out with five types of plant baits in soils infested with R. solani showed that eucalypt twig segments were more readily colonised and allowed detection of the fungus at lower inoculum densities, showing high detection sensitivity across the tested clonal garden soils. Other baits had high colonisation levels, but varied greatly in sensitivity according to the tested soil. These results indicate that eucalypt twig segments were the most effective bait to estimate Rhizocronia inoculum density in clonal garden soils. [ABSTRACT FROM AUTHOR]

Copyright of American Potato Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stem cuttings from potato plants are frequently used in multiplication programs for disease-free cultivars. The survival of these leafy cuttings is often very poor, and thus various techniques were investigated which were designed to increase rooting and cutting survival. Stock plants of cultivars 'Caribe,' 'Jemseg,' 'Keswick,' 'Russet Burbank,' 'Sable,' 'Sebago' and 'Shepody' were grown in the greenhouse under long days. Promoting growth of the axillary shoots was successfully achieved by shading the shoot apex with aluminum foil. Trimming the outer leaves of the cuttings was deleterious to both survival and rooting. A rooting hormone improved root initiation and development, and the use of shade cloth or intermittent mist increased survival by reducing wilting. A rooting substrate of vermiculite: perlite (1:1) provided sufficient aeration, support and drainage for the cuttings. Antitranspirants sprayed on the stock plants prior to the excision of cuttings and also on the excised cuttings did not improve rooting or survival. The addition of activated charcoal (1% w:w) increased rooting of the cuttings and improved vigor of potted plants obtained from the cuttings. [ABSTRACT FROM AUTHOR]

Cassava plants were started in the greenhouse either from small cuttings (2.0 mg P/cutting) or large cuttings (20.2 mg P/cutting) in a subsurface Oxisol not inoculated or inoculated with Glomus aggregatum at target soil solution P concentrations of 0.003-0.2 mg l. Vesicular-arbuscular mycorrhizal (VAM) fungal colonization levels in excess of 60% were attained on cassava roots irrespective of the size of cutting material used or target soil solution P status. However, plants started from large cuttings grew faster and better than those started from smaller ones. Cassava was found to be very highly dependent on VAM fungi if grown from small cutting but only marginally dependent if grown from large cuttings. The lower dependence of cassava on VAM fungi when started from larger cuttings appears to be related to the high P reserve in these cuttings and hence the low requirement of the plants for soil P until the P reserve in the cuttings is significantly depleted. [ABSTRACT FROM AUTHOR]

Fifty-two clones in twenty-two full-sib families were represented in a field trial. All cuttings were taken from hedged ortets which were four years from seed, but had been cut back periodically to one metre high since age two. One-year-old seedlings, from a seed orchard, where most of the parents of the clones were represented, were used as controls. The trial was assessed for Dothistroma needle blight infection six years after planting. The mean infection level of all the cuttings was 21.1%, compared to 29.8% for the seedlings. This difference was attributed to the greater maturation age of the cuttings. It was calculated that if the best 10% of the clones were selected, infection could have been further reduced to 12%, a level where other disease control measures would be considered unnecessary. [ABSTRACT FROM AUTHOR]

We consider the half-space range-reporting problem: Given a set S of n points in ℝ, preprocess it into a data structure, so that, given a query half-space γ, all k points of S ∩ γ can be reported efficiently. We extend previously known static solutions to dynamic ones, supporting insertions and deletions of points of S. For a given parameter m, n ≤ m ≤ n and an arbitrarily small positive constant ɛ, we achieve O( m) space and preprocessing time, O(( n/ m log n+k) query time, and O(mn) amortized update time ( d ≳ 3). We present, among others, the following applications: an O(n)-time algorithm for computing convex layers in ℝ, and an output sensitive algorithm for computing a level in an arrangements of planes in ℝ, whose time complexity is O(( b+n) n, where b is the size of the level. [ABSTRACT FROM AUTHOR]

Susceptibility to Phytophthora cinnamomi is one of the main traits in Castanea sativa breeding programs. An inoculation experiment using 25 control pollinated families, with seedlings of these families cloned by cuttings, was conducted by soil infestation with one P. cinnamomi isolate. Forty-seven days after inoculation, foliar and root collar symptoms and root necrosis were recorded. The data were analyzed using a model based on restricted maximum pseudolikelihood methods of the GLIMMIX procedure to estimate the additive, dominance and epistatic components of the genetic variance, as well as the narrow sense heritability and the breeding values. At the end of the experiment, the percentages of dead plants ranged from 4% to 56% in C. sativa, and 18% to 20% in backcrosses to C. sativa, with much lower percentages in the F1 hybrids (C. crenata × C. sativa). Foliar symptoms were proportional to mortality, affecting 28% of the plants, but root collar lesions and root necrosis were more prevalent, affecting 65% and 84% of the plants, respectively. The proportions of genetic to phenotypic variance, 0.50-0.63, and the estimated values of narrow-sense heritability, 0.30-0.46, indicate that resistance to P. cinnamomi is under moderate to moderately high genetic control caused mainly by additive genetic variance. A high number of backcrosses to C. sativa showed good breeding values for resistance to P. cinnamomi. [ABSTRACT FROM AUTHOR]

The effect of agrochemicals on the survival rate of seedling stock has been studied. It has been proven that Radipharm and Master 13:40:13 contribute to a significant increase in the survival rate and growth of seedling stock of apple and quince cuttings. [ABSTRACT FROM AUTHOR]