丙环唑对水稻恶苗病菌(Fusarium fujikuroi)生物活性研究

 丙环唑是一种具有广谱活性的三唑类杀菌剂。本研究首次采用菌丝生长速率法建立了浙江省绍兴市、江苏省淮安市和黑龙江省尚志市不同地区的80株水稻恶苗病原菌(Fusarium fujikuroi)对丙环唑的敏感性基线,测定了丙环唑对水稻恶苗病菌的生理影响和对水稻的安全性。结果表明: 丙环唑对水稻恶苗病菌菌丝生长的有效抑制中浓度(EC₅₀值)范围在0.029 8~0.211 0 μg·mL^-1,EC₅₀平均值为(0.106 7 ± 0.004 4) μg·mL^-1。水稻恶苗病菌经0.1 μg·mL^-1(EC₅₀平均值)或3 μg·mL^-1(EC₉₀平均值)丙环唑处理后,分生孢子产量显著降低,细胞膜通透性显著升高;3 μg·mL^-1丙环唑不影响水稻恶苗病菌细胞核的分布与定位,但可以使细胞壁缢缩,菌丝顶端膨大,破坏水稻恶苗病菌细胞膜和细胞器。丙环唑浓度为不超过200 μg·mL^-1时,对水稻种子发芽率和株高无显著影响,同时可显著增加水稻鲜重;当浓度为500 μg·mL^-1时,对水稻种子发芽率、株高和鲜重均无显著性影响;当浓度达到1 000 μg·mL^-1时,发芽率显著降低但株高和鲜重无显著性差异;水稻种子发芽长度随丙环唑浓度升高而降低。本研究明确了丙环唑对水稻恶苗病菌的生物活性和对水稻的安全性,为丙环唑防治水稻恶苗病提供了指导,并进一步加深对丙环唑作用机理的认识。

Activity of the Triazole Fungicide Propiconazole Against Fusarium fujikuroi

Propiconazole is a triazole fungicide with broad-spectrum activities. In this study, baseline sensitivity of Fusarium fujikuroi to propiconazole was firstly determined using 80 isolates collected from young diseased rice of different fields in Shaoxing of Zhejiang Province, Huaian of Jiangsu Province and Shangzhi of Heilongjiang Province by mycelial growth assay. Physiological effect of propiconazole against F. fujikuroi and its safety on rice were measured. EC₅₀ values ranged from 0.029 8 to 0.211 0 μg·mL^-1 with the average value of (0.106 7 ± 0.004 4) μg·mL^-1 for mycelial growth. After 0.1 μg·mL^-1(the average EC₅₀) or 3 μg·mL^-1(the average EC₉₀) propiconazole treated, conidial production decreased significantly and cell membrane permeability increased markedly. 3 μg·mL^-1 propiconazole did not affect the distribution of cell nucleus of F. fujikuroi but could constricte the septum, dilate the tops of the hyphae and damage the membrane and organelle structure of F. fujikuroi. When the concentration of propiconazole was less than 200 μg·mL^-1, the germination rate and plant height of rice seeds were not significantly affected, but the fresh weight of rice was increased. At the concentration of 500 μg·mL^-1, propiconazole had no significant effect on the germination rate, plant height and fresh weight of rice seeds. When the concentration reached 1 000 μg·mL^-1, the germination rate of rice decreased significantly, but there was no significant difference in plant height and fresh weight. The germination length of rice seeds decreased with the increase of propiconazole concentration. These results provide useful information for the management of rice bakanae disease by propiconazole and further increase our understanding about the mode of action of propiconazole against phytopathogens.