1985 Volume 31 Pages 59-62
Onions grown in the recently reclaimed area of Ariake polder land in Saga prefecture were found to be less resistant to black mold caused by Aspergillus niger VAN TIEGHEM than those grown in areas cultivated for a longer period of time. The contents of Mg++ and Na+ and K+ in the soil of the recently reclaimed areas were about two times higher than those in the soil of the areas cultivated for a long period of time. In a water culture experiment, Ca++ absorption by onion grown in liquid medium with high contents of Mg++ and Na+ decreased when compared to that of onion grown in a solution with low contents of Mg++ and Na+. On the other hand, the onions cultured in a medium with high contents of Mg++ and Na+ showed an incresed susceptibility to the disease. Based on the results of experiments on the inhibition of the antagonistic absorption by Mg++ and Na+, negative correlations between Ca++ content in onion bulbs and the susceptibility of onion to the disease were detected.
