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.
Lanthanum nitrate, Vigna sinensis L., germination, susceptibility to infection, antioxidant enzymes, defensive mechanisms.