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首页> 外文期刊>Plant and Soil >Influence of cultural practices on edaphic factors related to root diseasein Pinus nursery seedlings
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Influence of cultural practices on edaphic factors related to root diseasein Pinus nursery seedlings

机译：栽培方式对松苗期根系相关根部营养因子的影响

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Conifer seedlings grown in bare-root nurseries are frequently damaged and destroyed by soil-borne pathogenic fungi that cause root rot. Relationships between nursery cultural practices, soil characteristics, and populations of potential pathogens in the soil were examined in three bare-root tree nurseries in the Midwestern USA. Soil-borne populations of Fusarium spp. and Pythium spp. were enumerated as a function of soil depth in the upper 42 cm; red and white pine seedling root systems were assessed visually for signs of root rot. Soil organic carbon and resistance to cone penetration (as a function of depth) were augmented by saturated hydraulic conductivity (K-sat), water retention characteristic, texture and pH at selected depths. Cone index (CI) provided accurate `fingerprints' of cultural practices in each nursery. A tillage pan due to rotary tillage was detected by CI in the Minnesota and Wisconsin nurseries, but no such tillage pan was indicated in the Michigan nursery, which did not use rotary tillage. Curves of CI also indicated differing maximum depth of tillage disturbance between nurseries; maximum rooting depth based on 3 MPa CI were different among nurseries. Vertical distribution of soil-borne Fusarium spp. reflected the vertical incorporation pattern associated with the type of tillage implement used to incorporate cover crop residue prior to Pinus seedling establishment. Peak numbers of Fusarium spp., from 250 to 950 colony-forming units (cfu g(-1) dry soil) were recorded between 12 - 24 cm depth in two nurseries using a moldboard plow for incorporation while steadily decreasing populations, from 1800 to 250 cfu g(-1) dry soil, were found from 0 to 15 cm in the third nursery using a disc. Vertical distribution of the Fusarium spp. also correlated with organic carbon levels, which suggested that cover-crop incorporation and conifer rooting had determined the location of soil-borne Fusarium spp. propagules. K-sat suggest that tillage pans caused by rotary tillage may impede drainage during nearly daily irrigation enough to cause physiological stress to the seedlings and predispose them to disease. Low levels of mortality (from < 1% to 5%) were observed in two-year-old Pinus seedlings while disease severity varied by nursery and seedling species. Tillage should be used to control depth placement of biomass residue and pathogenic fungal propagules, and adjusted to prevent tillage pans within the seedling root zone. More studies are needed to determine the impact of these cultural controls on the need and application depth of fumigation for pathogen control.
机译：在裸露的根苗圃中生长的针叶树幼苗经常受到土壤传播的致病真菌的破坏和破坏，导致根腐病。在美国中西部的三个裸露树苗圃中，研究了苗圃文化习俗，土壤特征和土壤中潜在病原菌种群之间的关系。镰刀菌的土壤传播种群。和腐霉属。被列举为上部42 cm土壤深度的函数;目视评估红色和白色松树幼苗的根系是否腐烂。在选定的深度，饱和的水力传导率（K-sat），保水特性，质地和pH值可以提高土壤有机碳和抗圆锥穿透性（作为深度的函数）。圆锥指数（CI）为每个托儿所的文化习俗提供了准确的“指纹”。 CI在明尼苏达州和威斯康星州的苗圃中检测到由旋转耕作引起的耕作盘，但在密歇根苗圃中没有使用旋转耕作的密歇根苗圃中没有这种耕作盘。 CI的曲线也表明育苗间最大耕作扰动的最大深度不同。育苗间基于3 MPa CI的最大生根深度不同。土壤传播的镰刀菌属植物的垂直分布。反映了垂直整合模式，该模式与在松树幼苗建立之前用于覆盖农作物残留物的耕作机具类型有关。在两个苗圃中，使用a板犁并入，同时稳步减少种群，从1800减少到250到950个菌落形成单位（cfu g（-1）干燥土壤）的镰刀菌的峰值数量在12至24 cm深度之间记录。在第三个苗圃中，使用圆盘在0至15厘米之间发现了250 cfu g（-1）干燥土壤。镰刀菌属的垂直分布。也与有机碳水平相关，这表明表皮作物的掺入和针叶树的生根决定了土壤传播的镰刀菌属植物的位置。繁殖体。 K-sat认为，轮耕造成的耕作盘可能在几乎每天的灌溉过程中阻碍排水，足以对幼苗造成生理压力并使其易患病。在两岁的松树幼苗中观察到较低的死亡率水平（从<1％到5％），而疾病的严重程度则因苗圃和幼苗的种类而异。耕作应用于控制生物量残留物和病原性真菌繁殖体的深度放置，并应进行调整以防止在苗根区域内出现耕作盘。需要更多的研究来确定这些文化控制对熏蒸对病原体控制的需求和熏蒸深度的影响。

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