木薯根系分泌物与土壤浸出液对橡胶树2种致病菌的化感效果

采用平板试验,通过生长速率法分析木薯根系分泌物及其土壤浸出液对橡胶树白根病病菌及棒孢霉落叶病病菌的化感效果,为判断胶园林下种植木薯的可行性提供理论依据。结果表明：（1）木薯根系分泌物对橡胶树白根病和棒孢霉落叶病病菌均表现为化感促进效果,但在任一处理时间,不同浓度间对白根病病菌的化感效果与对照均未达显著差异,而对棒孢霉落叶病病菌的化感效果呈现明显的剂量效应,浓度达40 mg/mL时,化感促进效果与对照达到显著水平。（2）木薯根系分泌物的任一浓度,对橡胶树白根病和棒孢霉落叶病病菌的化感效果,在不同处理天数间均未达到显著水平。（3）木薯土壤浸出液对橡胶树白根病和棒孢霉落叶病病菌均呈现化感促进效果,且存在明显的剂量效应;对橡胶树白根病病菌,处理后2 d,达到显著化感效果所需浸出液浓度至少为40 mg/mL,处理后3 d和处理后4 d,达到显著化感效果所需浸出液浓度至少为8 mg/mL;对棒孢霉落叶病病菌,在任一处理时间达到显著化感效果的浸出液浓度均至少为200 mg/mL。（4）土壤浸出液小于8 mg/mL时,3个处理时间之间的橡胶树白根病病菌化感效果无显著差异,当浓度达到40 mg/mL时,处理后2 d的化感促进效果显著大于处理后3 d和4 d;4种土壤浸出液的任一浓度,对橡胶树棒孢霉落叶病病菌的化感效果在不同处理时间之间均未达到显著差异。所以说,幼龄胶园间作木薯会在一定程度上促进橡胶树棒孢霉落叶病和白根病的发生。

Allelopathy of Root Exudates and Aqueous Extracts from Soil of Cassava to Rigidoprus lignosu and Corynespora cassiicola of Hevea brasiliensis

In order to study the allelopathic effect of the root exudates and aqueous extracts from the soil of cassava on the Rigidoporus lignosus and Corynespora cassiicola of rubber tree, the growth of the C. cassiicola and R. lignosus of rubber tree were measured using the mycelial growth rate method. The root exudates of cassava could promote the growth of the C. cassiicola and R. lignosus of Hevea brasiliensis. The effect on C. cassiicola of four concentrations was not obvious at any treatment times, while the effect on R. lignosus was more obvious with the concentration increase. When the concentration was 40 mg/mL, the effect on R. lignosus was significant. The allelopathic effect of the four concentration root exudates on C. cassiicola and R. lignosu was not obvious at any treatment days. The allelopathic effect of the aqueous extracts from the soil on C. cassiicola and R. lignosus showed promotion. With the concentration increased, the promotion effect increased gradually. On the 2nd day after treatment, there was a significant effect on R. lignosus when the concentration was 40 mg/mL, while there was a significant effect when the concentration was 8 mg/mL on the 3rd and 4th day after treatment. There was a significant effect on C. cassiicola when the concentration was 200 mg/mL at any treatment days. When the concentration of the aqueous extracts from the soil was less than 8 mg/mL, the effect on R. lignosuof on the 3rd day was not obvious. When the concentration was more than 40 mg/mL, the allelopathic effect on R. lignosu on the 2nd day after treatment was significantly higher than that on the 3rd day and 4th day after treatment. The effect of the four concentration aqueous extracts from the soil on C. cassiicola was not obvious. Intercropping cassava in the rubber plantation could promote the occurrence of Corynespora leaf falling disease and white root disease of H. brasiliensis to a certain extent.