Abstract:

【Objective】 To determine the spectral range of light required for lesion formation and the effect of temperature on the expression of lrd lesions, the response of lrd expression to light and temperatures was tested for certain mutants in Oryza sativa L. 【Method】 Six lrd mutants derived from Indica and Japonica by gamma-ray mutagenesis simultaneously were illuminated by Light Emitting Diode (LED) light and were cultured in two different growth chambers set at three different temperature regimes. Lesions occurred on leave were observed and photographed for comparison the effect of different treatments. 【Result】 The expression of lrd lesions for lrd31 was induced by UV light, that of lrd36 was induced by yellow light, that of lrd37and lrd35 was induced by blue light, and lrd32 or lrd40 expressed lesion under all illuminated light. lrd32, lrd36 and lrd37 formed lesion under all culturing temperatures, and cooler environment accelerated their lesion expression, lrd35 and lrd40 were suppressed at high temperature and expressed at intermediate temperature, also accelerated under lower temperature. But lrd31 formed lesion only under intermediate temperature, and no lesion formation at high or lower culturing temperature. 【Conclusion】 The expressions of lrd lesions are light-dependent, different genotypes of lrd mutants in rice need specially spectral range of light. Temperature is another factor influencing lrd expression. The lower temperature seemed to enhance the expression of lrd phenotype.

Key words: Orazy sativa L., lesion resembling disease, illumination induction, temperature effect