施氮对水稻抗白叶枯病反应的影响

EFFECT OF NITROGEN APPLICATION ON THE EXPRESSION OF RESISTANCE IN RICE TO BACTERIAL BLIGHT (XANTHOMONAS CAMPESTRIS PV. ORYZAE)

研究了3个施氮水平(N_0,N_(90),N_(180))对9个水稻品种抗白叶枯病反应的影响。晚稻苗期接种强致病菌株76-25 SR-l后15d,N_(180)处理病斑长度显著(P=0.01)高于N_(90)和N_0处理,但晚稻成株期剑叶接种该菌株后20d,仅中间反应型品种处理间存在显著差异。在早稻成株期用该菌株处理得到类似的结果,而用弱致病力菌株83-5接种时均无显著差异。各试验中品种抗病强弱次序不受施氮水平影响。TLC结果表明施氮后游离氨基酸尤其是Clu和Asp含量显著上升,而还原糖尤其是蔗糖含量显着下降。因此,可得出结论;氮素可在某种程度上尤其是在苗期影响水稻对强致病力菌株的抗性表现。高游离氨基酸和低还原糖似与病斑增长有关。

The effect of N application on the expression of resistance in 9 dif-ferent rice cvs. to bacterial blight at 3 levels of N(N_0, N_(90) and N_(180) wasinvestigated. In the seedling test of late rice, the lesion lengths in N_(180) treat-ment were significantly (P=0.01)higher than those in N_(90) and N_(0) treatmentsat 15 days after inoculation with a virulent isolate 76-25 SR-1. In the test of flagleaves of late rice, significant difference was pressent only in the case of interme-diate cvs. at 20 days after inoculation with the same isolate. Similar results wereobtained in the adult plant test of early rice. On the other hand, no significantdifference was recorded in the response of those cvs. (except in replace of IR 22for IR 20) to another weak isolate 83-5. TLC analysis indicated that the longerlesions seemed to be associated with the higher content of free amino acids (esp-ecially Asp, Glu) and lower content of reducing sugars, especially sucrose. Thosefindings suggested that N application could effect, to some extent, the expressionof resistance in rice to a virulent isolate of Xanthomonas campestris pv. oryzaeespecially at the seedling stage.