溫度與濕度對山葵黑心病發生之影響

Abstract

山葵黑心病菌(Phoma wasabiae)之柄孢子發芽、菌絲生長及柄子殼形成最適溫度爲20-28 C，引起山葵發病之最適宜溫度是20-25 C，在相對濕度98-100%及水份潛勢-1~-10 bars問有利於病原菌柄子殼產生、柄孢子釋放、柄孢子發芽及菌絲生長。盆栽及田間試驗，顯示相對濕度愈高(55-100%)，山葵黑心病之發生愈趨嚴重。按達邦及淸境山葵栽培區之氣象及山葵黑病週年發生的資料顯示，氣象因子與山葵黑心病之發生間具有密切的關係，其中尤以高濕多雨季節發生較爲嚴重。將達邦山葵栽培區1991年1月6月之氣象資料與病勢進展進行單相關分析，結果顯示，病勢進展(Y)和雨量(X_1)或降雨日數(X_2)成正相關(Y = 0.306 + 0.077X_1 , r = 0.982 ; Y =-5.85 + 2.273 X_2 , r= 0.878)，複因子迴歸分析結果顯示，病勢進展與溫度(X_3)、濕度(X_4)、雨量及降雨日數有密切的關係(Y= 4.042 +0.028 X_1-0.246 X_2, , r=0-983 ; Y=66.15 + 0.092 X_1-0.745 X_4 , r=0.989; Y= 0.182 + 0.076 X_1 + 0.036 X_2 , r 0.982 ; Y=169.463 + 0.095 X_1 + 1.279 X_3 -2.132 X_4 , r= 0.998 ; Y = 104.914 + 0.081 X_1 + 0.742 X_2 -1.212 X_4 . r = 0.995)。 The laboratory studies showed that the favorable temperature for pycnidiospore germination mycelial growth, and pycnidia formation of Phoma wasabiae was 20-28 C. The optimum temperature for leaf infection was 20-25 C. High relative humidity (98-100%) and high water potential (-1 ~ -10 bars) were beneficial to pycnidia formation, pycnidiospore release, pycnidiospore germination and mycellial growth. The growth chamber and field experiments also indicated that the disease incidence and severity increased as relative humidities increased. The weather condition in wasabi's cultivation fields at Ta pang and Ching-jing was closely related to occurrence of the disease surveyed in 1991. Analyses of cor-relation between disease development (Y) and single meteorological factors from January to June in 1991 at Ta-pang cultivation field revealed that the relationship between disease development and rain fall (X_1) or raining days (X_2) was significantly positive (Y= 0.306 + 0.077 X_1, r = 0.982; Y =-5.85 + 2.273 X_2, r = 0.878). Polynominal regression analysis showed that disease development was associated with temperature (X_3), relative humidity (X_4), rainfall and raining days (Y= 4.042+ 0.028 X_1 - 0.246 X_3, r = 0.983; Y = 66.15 + 0.092 X_1 - 0.745 X_4, r = 0.989; Y = 0.182 + 0.076 X_1 + 0.036 X_2, r = 0.982; Y = 169.463 + 0.095 X_1 + 1.279 X_3 - 2.132 X_4, r = 0.998; Y = 104.914 + 0.081 X_1 + 0.742 X_2-1.212X_4, r= 0.995).