Effect of seed damage and metalaxyl seed treatment on seedling blight of field pea

Non-Peer ReviewedWhen cool, wet conditions occur at seeding, soil-bone diseases can severely reduce stand establishment in field pea. Seed that has been damaged by rough handling (augering or dropping) is particularly vulnerable to injury from Pythium spp. Field trials were conducted over 3 yr to assess the impact of seed rot, damping-off and seedling blight on seedling establishment and seed yield from damaged field pea seed. The effect of fungicide seed treatment was also examined. Mechanical damage to the seed reduced seedling emergence and seed yield. Seed treatment with metalaxyl (Apron) reduced the impact of seed damage, but did not always restore emergence and seed yield to the same level as from undamaged seed. Differences among cultivars were small relative to the effect of seed injury. This study showed that planting fungicide-treated, high quality field pea seed was an effective means to maximize emergence and stand establishment for commercial field pea production

Study of heterogeneous nucleation of eutectic Si in high-purity Al-Si alloys with Sr addition

The official published version can be accessed from the link below - Copyright @ 2010 The Minerals, Metals & Materials Society and ASM InternationalAl-5 wt pct Si master-alloys with controlled Sr and/or P addition/s were produced using super purity Al 99.99 wt pct and Si 99.999 wt pct materials in an arc melter. The master-alloy was melt-spun resulting in the production of thin ribbons. The Al matrix of the ribbons contained entrained Al-Si eutectic droplets that were subsequently investigated. Differential scanning calorimetry, thermodynamic calculations, and transmission electron microscopy techniques were employed to examine the effect of the Sr and P additions on eutectic undercoolings and nucleation phenomenon. Results indicate that, unlike P, Sr does not promote nucleation. Increasing Sr additions depressed the eutectic nucleation temperature. This may be a result of the formation of a Sr phase that could consume or detrimentally affect potent AlP nucleation sites.This work is financially supported by the Higher Education Commission of Pakistan and managerially supported from the OAD

An epitaxial model for heterogeneous nucleation on potent substrates

© The Minerals, Metals & Materials Society and ASM International 2012In this article, we present an epitaxial model for heterogeneous nucleation on potent substrates. It is proposed that heterogeneous nucleation of the solid phase (S) on a potent substrate (N) occurs by epitaxial growth of a pseudomorphic solid (PS) layer on the substrate surface under a critical undercooling (ΔT ). The PS layer with a coherent PS/N interface mimics the atomic arrangement of the substrate, giving rise to a linear increase of misfit strain energy with layer thickness. At a critical thickness (h ), elastic strain energy reaches a critical level, at which point, misfit dislocations are created to release the elastic strain energy in the PS layer. This converts the strained PS layer to a strainless solid (S), and changes the initial coherent PS/N interface into a semicoherent S/N interface. Beyond this critical thickness, further growth will be strainless, and solidification enters the growth stage. It is shown analytically that the lattice misfit (f) between the solid and the substrate has a strong influence on both h and ΔT ; h decreases; and ΔT increases with increasing lattice misfit. This epitaxial nucleation model will be used to explain qualitatively the generally accepted experimental findings on grain refinement in the literature and to analyze the general approaches to effective grain refinement.EPSRC Centre for Innovative Manufacturing in Liquid Metal Engineerin

Effects of soil temperature, seeding depth and seeding date on rhizoctonia seedling blight and root rot of chickpea

Effects of soil temperature, seeding depth, and seeding date on rhizoctonia seedling blight and root rot of chickpea. Rhizoctonia solani Kühn, a prevalent fungal pathogen in cultivated prairie soils, can be an important factor affecting seedling establishment of chickpea (Cicer arietinum L.). Studies were undertaken to determine the impact of different soil conditions on seedling establishment, development of root rot, and productivity of desi (Tyson) and kabuli (Sanford) chickpea plants sown in the presence of R. solani AG-4. The impact of soil and air temperatures and seeding depth was studied under controlled conditions, and the influence of seeding date was investigated at three field sites. The host responded to warm soils by increasing its growth rate, and the pathogen by increasing its virulence. The kabuli cultivar, Sanford, showed greater susceptibility to root rot caused by R. solani than the desi cultivar, Tyson. Root rot and shoot infection levels increased with soil temperature for both cultivars, but reached maximum values at substantially lower temperatures for Sanford. Shoot biomass of infected treatments for this cultivar was substantially lower than the controls, while the biomass of Tyson was affected to a lesser degree. Air temperatures of 17/3 °Cday/night allowed relatively unhindered plant growth, even of the more susceptible cultivar, Sanford, in the presence of R. solani, while warmer and cooler temperatures resulted in high mortality and diminished plant growth in surviving plants. Seedling emergence and seedling dry weight were greater at a seeding depth of 2 cm than at 5 cm for seedlings grown in infested soil. In inoculated field plots, seedling emergence was greatest in treatments seeded in late May to early June compared those seeded in early or mid-May; in noninoculated treatments, both emergence and yield were lower in treatments seeded in late May than at the earlier seeding dates. Seeding date did not affect the occurrence of root rot. Incidence de la temperature du sol, de la profondeur des semis et de la date d’ensemencement sur la fonte des semis par Rhizoctonia et sur le pourridié du pois chiche. Can. J. Plant Sci. 84: 901–907. Rhizoctonia solani Kühn, champignon pathogène courant dans les sols cultivés des prairies, peut nuire considérablement à l’implantation du pois chiche (Cicer arietinum L.). On a donc entrepris des études pour déterminer l’incidence de divers états du sol sur l’enracinement des plantules, ’apparition du pourridié et la productivité des pois chiches desi (Tyson) et kabuli (Sanford) semés en présence de R. solani AG-4. On a vérifié les effets de la température du sol et de l’air et de la profondeur des semis en milieu contrôlé, tandis que l’incidence de la date d’ensemencement a été évaluée sur le terrain à trois endroits. Quand le sol est chaud, la plante pousse plus rapidement , mais l’agent pathogène est plus virulent. Sanford (le cultivar kabuli) est plus sensible au pourridié causé par R. solani que le cultivar desi Tyson. La gravité du pourridié et le degré d’infection des pousses augmentent avec la température du sol chez les deux cultivars, mais atteint le maximum à une température nettement plus basse chez Sanford. La biomasse des pousses infectées de ce cultivar était passablement plus faible que celle des témoins, Tyson étant moins affecté sur ce plan. Une température diurne/nocturne de 17/3 °C permet à la plante de croître relativement sans difficulté en présence de R. solani , meme pour Sanford, qui est plus sensible. Une température plus élevée ou plus basse se traduit par un taux de mortalité accru et une croissance plus lente chez les plants survivants. Le pourcentage de levée et le poids sec des plantules sont plus élevés quand on sème les graines à 2 cm plutôt qu’à 5 cm de profondeur dans les sols contaminés. Dans les parcelles inoculées, le pourcentage de levée est plus élevé quand on sème les graines entre la fin de mai et le début de juin que lorsque les semis ont lieu au début de mai ou au milieu du mois; dans les parcelles non inoculées, le pourcentage de levée et le rendement sont plus faibles quand on sème à la fin de mai plutôt qu’à une date antérieure. La date d’ensemencement n’a aucune incidence sur la manifestation du pourridié

Study of heterogeneous nucleation of eutectic Si in high-purity Al-Si alloys with Sr addition

The official published version can be accessed from the link below - Copyright @ 2010 The Minerals, Metals & Materials Society and ASM InternationalAl-5 wt pct Si master-alloys with controlled Sr and/or P addition/s were produced using super purity Al 99.99 wt pct and Si 99.999 wt pct materials in an arc melter. The master-alloy was melt-spun resulting in the production of thin ribbons. The Al matrix of the ribbons contained entrained Al-Si eutectic droplets that were subsequently investigated. Differential scanning calorimetry, thermodynamic calculations, and transmission electron microscopy techniques were employed to examine the effect of the Sr and P additions on eutectic undercoolings and nucleation phenomenon. Results indicate that, unlike P, Sr does not promote nucleation. Increasing Sr additions depressed the eutectic nucleation temperature. This may be a result of the formation of a Sr phase that could consume or detrimentally affect potent AlP nucleation sites.This work is financially supported by the Higher Education Commission of Pakistan and managerially supported from the OAD