金線蓮莖腐病的最初感染源－筆筒樹的氣根蛇木屑

Initial Inoculum of Stem Rot of Taiwan Anoectochilus-Aerial Root of Common Tree-fern

謝式坢鈺(S. P. Y. Hsieh) ； 黃士峰(S. F. Huang) ； 高碩廷(S. T. Kao)

《植物病理學會刊》 4卷2期 (1995/06) Pp. 69-75

https://doi.org/10.6649/PPB.199506_4(2).0003

摘要

栽培金線蓮基質中之蛇木屑(筆筒樹的氣根)，在未種植金線蓮之前就可以分離到莖腐病菌Fusarium oxysporum，蛇木屑在高濕下會從斷口處長出病菌的菌絲與大孢子叢。以冷凍切片機做切片，可看到厚膜孢子和菌絲貫穿於蛇木屑組織中，以棉藍透化筆筒樹的葉部組織也可看到菌絲與厚膜孢子。市場購回的7袋蛇木屑中有4袋可以分離到金線蓮莖腐病菌。筆筒樹的根、莖、葉、芽、絨毛、孢子與氣根都可以分離到莖腐病菌，且分離率隨離地面的高度遞減，根部90%以上，而孢子爲16.7%。筆筒樹的根圈土壤也有莖腐病菌，其密度約爲200 propagules/g。蛇木屑分離之菌株FF-001和筆筒樹葉片分離的菌株FF-002,在形態與培養特性上都和金線蓮病株分離的菌株TF-001相似，而接種到金線蓮都會產生典型的莖腐病病徵；但筆筒樹未張開葉片、成長葉片和葉柄接種金線蓮莖腐病菌或分離自蛇木屑和筆筒樹的F. oxysporum都不會產生病徵，蛇木屑的水浸出液能促進莖腐病菌孢子的發芽，添加蛇木屑的基質加入莖腐病菌孢子懸浮液後，莖腐病菌族群的密度會增加。用沸水消毒30 min方可完全消滅蛇木屑中之病菌。含有蛇木屑的栽培基質在種植前病菌的族群常有2x10 propagules/g以上，種植金線蓮四個月後莖腐病罹病平均率高達95%，而基質的莖腐病菌的族群也增加至約6.3× 104 propagules/g，以不含蛇木屑之基質種植金線蓮爲對照，4個月後仍無莖腐病的發生。

關鍵字

金線蓮 ； 莖腐病 ； 筆筒樹 ； 蛇木屑 ； 最初感染源

並列摘要

Aerial roots of common tree-fern (ARCTF), the main component of substrate used to grow Taiwan Anoectochilus, carried stem rot pathogen, Fusarium oxysporum before planting. Under high relative humidities hyphae and sporotochia grew out from broken surfaces of ARCTF. Frozen dissection revealed the existence of mycelia and chlamydospores inside tissues of ARCTF. Mycelia and chlamydospores of the pathogen were also clearly observed after clarification of leaf tissues with boiling cotton blue. F. oxysporum was isolated from four out of the seven ARCTF samples purchased from market. F. oxysporum was detectable not only in ARCTF but also in the tissues of roots, stems, leaves, petioles, folded leaves and spore of common tree-fern, and percentage of isolation was depended on the distances from the ground, the nearer the ground the higher percentages of isolation. The morphology and cultural characters of F. oxysporum isolated from ARCTF and leaves of common tree-fern were similar to those isolated from Taiwan Anoectochilus Typical stem rot symptoms were produced on Taiwan Anoectochilus inoculated with F. oxysporum isolated from ARCTF and leaves of common tree-fern. Water seepage of ARCTF enhanced the conidal germination of F. oxysporum. F. oxysporum in the ARCTF was not killed after treated in boiling water for 20 min. Soils from rhilzosphere of common tree-fern contained approximately 2 X 10^3 propagules/g. The population of F. oxysporum was about 2 X 10^3 propagules/ g in the substrate mixed with ARCTF before planting Taiwan Anoectochilus. After planting of Taiwan Anoectochilus t e pathogen increased rapidly and reached 6.3 X 10^4 propagules/ g, and the disease incidence reached up to 95% four months after planting. No stem rot was observed in the check substrate without ARCTF.

並列關鍵字

Taiwan Anoectochilus ； stem rot ； Fusarium oxysporum ； initial inoculum ； common tree-fern