The main target of the present work was to investigate the effects of two different concentrations (1 and 5 ppm) of lanthanum nitrate on the susceptibility of V.sinensis seeds to pathogen infection during germination stage.The relatively low applied concentration of La-nitrate (1 ppm) led to rapid emergence of radicles, significant increase in percentage of germination and a significant decrease in percentage of infected seeds. Also,there was a significant increase in major growth attributes of the developed seedlings. The biochemical activities of Vigna sinensis L. responded well to the low concentration of La-nitrate and participated in acquisition of pathogen tolerance and in growth enhancement of the seedlings. Thus, in response to the relatively low applied concentration of La-nitrate a significant increase in total soluble sugars, amino acids, total nitrogen, antioxidant enzymes, phenolic compounds was obtained mean while the content of cytosolic calcium subjected to a significant decrease. On the other hand, application of a relatively high concentration of La-nitrate (5 ppm), via disturbing the biochemical activities had retarded seed germination, major defensive mechanism, hence increased susceptibility to pathogen infection and retarded seedling growth.
Key words: Lanthanum nitrate, Vigna sinensis L., germination, susceptibility to infection, antioxidant enzymes, defensive mechanisms.
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