| dc.description.abstract | 土壤中含有10 mM之尿素、概氮化鈣、硫酸銨、硝酸銨、氯化銨或亞硝酸鹽時，能顯著抑制白絹病菌菌核發芽。尿素、氟氮化鈣及亞硝酸鹽不但可抑制菌核發芽，並能殺死菌核，且可使土壤之pH值升高而呈微鹼性。硫酸按、硝酸銨、氯化銨加入土壤後，土壤之pH值降低呈偏酸性。50 mM時只能抑制菌核發芽而不能殺死之。硝酸鈣、硝酸鉀、氣化鉀等不影響土壤pH值，高濃度時，亦能抑制菌核發芽。過磷酸鈣能降低土壤pH值，且對菌核發芽及菌絲生長有益。磷酸銨雖可降低土壤pH值，但對菌核發芽並無顯著影響。土壤微生物相因添加不同之氮化合物及濃度而有相當大之差異。土壤中含100 mM之尿素或亞硝酸鹽時，不論在土壤中或菌核上，除細菌外，均無其他微生物。但10 mM時，則可促進土壤中之Fusarium spp.等微生物在菌核上定殖(Cofonization)，而硫酸銨等銨態氮化合物須在較高之濃度下才能促使Fusarium spp.和Trichodema spp.等微生物在菌核上定殖。
The germination of scicrotia of Scierotium rolfsii was significantly inhibited by 10 mM soil amendment of either one of the nitrogen compounds namely urea, calcium cyanamide, ammonium sulfate, ammonium nitrate, ammoniurn chloride, sodium nitrite or potassium nitrite. Among these nitrogen compounds, urea, calcium cyanamide and nitrites were found to inhibit sclerotial germination and kill sclerotia effectively. In addition, they were found to make the soil weakly alkaline by raising the soil pH. Amendments of 50 mM of either nitrogen compounds namely ammonium sulfate, ammonium nitrate or ammonium chloride decreased sclerotial germination but did not affect scicrotial viability. Calcium nitrate, potassium nitrate and potassium chloride did not affect soil acidity but inhibited scierotial germination under high salt concentration, Calcium superphosphate was found to decrease soil p1-I, facilitate scierotial germination and promote mycelial growth of soil pathogens. Ammonium phosphate decreased soil pH but did not affect scierotial germination. Soil microflora was affected by adding different types of nitrogen compounds at various concentrations into soil. when either urea or nitrite was added into soil at 100 mM concentration, no other soil microbes except bacteria were observed in the soil or on the sclerotia. However, at concentration of 100 mM, urea and nitrite promoted sclerotial colonizations of soil microorganisms such as Fusarium spp. etc. Higher concentration (i.e. 10mM) of soil amendments of ammonium compounds such as ammonium sulfate was found to be conducive to scierotial colonizations of soil microorganisms (such as Fusarium spp., Trichoderma spp., etc.). | en_US |
