硅对甘蔗黑穗病菌的体外抑菌效果研究

由鞭黑粉菌（Sporisorium scitamineum）引起的黑穗病是甘蔗（Saccharum spp.）生产上最重要的真菌病害。硅是植物生长过程中的有益矿质元素,能够提高植物对生物和非生物胁迫的抗性。目前,关于外源硅对甘蔗黑穗病菌的体外抑菌作用尚未见报道。本研究以硅酸钠（sodium silicate, Na₂SiO₃）和硅酸钾（potassium silicate, K₂SiO₃）处理甘蔗黑穗病菌,观察黑穗病菌的孢子萌发、菌落直径和菌丝生长情况,评价不同硅剂和pH对甘蔗黑穗病菌的体外抑菌效果。结果显示,0.5~20.0 mmol/L Na₂SiO₃和K₂SiO₃均完全抑制甘蔗黑穗病菌的孢子萌发,但1.0 mmol/L Na₂SiO₃促进甘蔗黑穗病菌菌落和菌丝的生长,10.0、20.0 mmol/L Na₂SiO₃和K₂SiO₃则显著抑制菌落和菌丝的生长,表明Na₂SiO₃和K₂SiO₃均会影响甘蔗黑穗病菌的生长,高浓度Na₂SiO₃和K₂SiO₃的抑菌效果明显。在不同pH条件下,低pH（5.87~10.86）处理下的甘蔗黑穗病菌孢子有萌发,但其萌发率随着pH的增大逐渐降低,高pH（≥10.96）完全抑制孢子萌发,此外,pH为9.40和11.57对菌落直径的抑制效果明显。调整pH为6.0的低浓度Na₂SiO₃（0~5.0 mmol/L）和K₂SiO₃（0~3.5 mmol/L）对孢子萌发影响小,但pH为6.0的高浓度Na₂SiO₃（7.0~20.0 mmol/L）和K₂SiO₃（5.0~20.0 mmol/L）显著抑制孢子萌发,表明相同pH水平下的K₂SiO₃比Na₂SiO₃及其对应pH处理对甘蔗黑穗病菌孢子萌发的抑制作用更为明显。研究结果为外源硅在甘蔗抗黑穗病的药效试验和防治机理研究提供参考。

Antifungal Effect of Silicon on Sporisorium scitamineum in vitro

Smut caused by Sporisorium scitamineum is the most important fungal disease in Saccharum spp. production. Silicon is a beneficial mineral element in plant growth, which can improve plant resistance to biotic and abiotic stresses. At present, the antifungal effect of exogenous silicon on S. scitamineum in vitro has not been reported. In this study, the spore germination, colony diameter and mycelium growth of the S. scitamineum were observed using sodium silicate (Na₂SiO₃) and potassium silicate (K₂SiO₃) to evaluate the antifungal effects of different silicon agents and pH on S. scitamineum in vitro. The spore germination of S. scitamineum was completely inhibited by 0.5-20.0 mmol/L Na₂SiO₃ and K₂SiO₃. The colony and hyphal growth of S. scitamineum were promoted by 1.0 mmol/L Na₂SiO₃, but was significantly inhibited by 10.0 mmol/L and 20.0 mmol/L Na₂SiO₃ and K₂SiO₃. The results suggested that Na₂SiO₃ and K₂SiO₃ could affect the growth of S. scitamineum, and high concentrations exhibited obvious antifungal effects. The spores could germinate at low pH (5.87-10.86), but the germination rate gradually decreased with the increase of pH. High pH (≥10.96) completely inhibited the spore germination. In addition, pH 9.40 and pH 11.57 significantly inhibited the colony growth. After adjusting pH to 6.0, low concentrations of Na₂SiO₃ (0-5.0 mmol/L) and K₂SiO₃ (0-3.5 mmol/L) had little effects on the spore germination, but high concentrations of Na₂SiO₃ (7.0-20.0 mmol/L) and K₂SiO₃ (5.0-20.0 mmol/L) significantly inhibited the spore germination. The results indicated that at the same pH level, the inhibition effect of K₂SiO₃ on the spore germination of S. scitamineum was better than that of Na₂SiO₃ and the corresponding pH treatment. This study would provide references for further pesticide effect test and control mechanism research on the resistance of sugarcane to smut.