Abstract

Key message

Young Pinus taeda trees may tolerate Leptographium terebrantis infection when stand conditions support new sapwood growth devoid of pathogen-induced occlusion.

Abstract

Leptographium terebrantis S. J. Barras and T. J. Perry is an opportunistic root pathogen that compromises the xylem function of infected trees and is commonly associated with Pinus taeda L. stands that experience an unexplained loss of vigor in the southeastern U.S. To understand the relationship between L. terebrantis inoculation density, sapwood occlusion, and sapwood function characterized by hydraulic conductivity and moisture content, an artificial inoculation study was conducted in young P. taeda trees in a naturally regenerated stand over a 24-week period in south central Alabama. Four levels of increasing stem inoculation were used as a surrogate for comparable levels of woody root inoculation followed by an evaluation of pathogen-induced occlusion, sapwood function, and fascicle physiology. Occlusion of old sapwood intensified as L. terebrantis inoculum density increased, but occlusion was absent in current-year sapwood. Occlusion reduced sapwood hydraulic conductivity and moisture content but did not interfere with stomatal conductance. The vertical spread of L. terebrantis was correlated with losses of sapwood hydraulic conductivity and moisture content due to occlusion. Results demonstrate that the sapwood function of P. taeda is tolerant of the pathogen vascular occlusion when stand conditions sustain adequate carbon fixation for occlusion-free stemwood growth.

中文翻译：

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阔叶松树对茎端接种Leptographium terebrantis的生理反应

摘要

关键信息

当林分条件支持新的边材生长而没有病原体引起的闭塞时，年轻的松树taeda树可能可以忍受terebrantis terebrantis感染。

抽象

Leptographium terebrantis SJ Barras和TJ Perry是机会性根病原体，会损害被感染树木的木质部功能，通常与taeda L.林分相关联。在美国东南部，林分经历了无法解释的活力丧失。了解Terebrantis接种之间的关系以水力传导率和水分含量为特征的密度，边材闭塞和边材功能，在幼龄斑节菜中进行了人工接种研究自然再生的树木在阿拉巴马州中南部站立长达24周。四种增加的茎接种水平被用作木薯根接种水平的替代指标，然后评估病原体诱导的咬合，边材功能和束生理。随着对虾L. terebrantis接种物密度的增加，旧边材的遮盖力也随之增强，但当年边材没有遮盖物。遮挡降低了边材的水力传导率和水分含量，但不干扰气孔导度。沙门氏菌的垂直蔓延与边材的水力传导率和水分含量的损失有关。结果证明的边材功能火炬松 当林分条件维持足够的碳固定以实现无阻塞的枯木生长时，其对病原体的血管阻塞具有耐受性。