摘要 : In two experiments young cabbage plants in the 4/6-leaf stage were supplied for eight weeks with nutrient solutions without nitrogen oN, phosphorus oP, calcium oCa or potassium oK in ordei to investigate the impact of withholding ... 展开 In two experiments young cabbage plants in the 4/6-leaf stage were supplied for eight weeks with nutrient solutions without nitrogen oN, phosphorus oP, calcium oCa or potassium oK in ordei to investigate the impact of withholding essential major elements on the development of black spot disease Alternaria brassicicola in intact leaves variant Int and detached leaf segments variant Seg, A complete solution Co that contained all mineral elements essential for the growth of the host plant served as control Lesion size in millimetres was measured as parameter of the pathogen activity. In the fust trial, solutions oN, oP, oCa, and Co were tested simultaneously in four replications Lesion size was estimated 5 days after inoculation dai In the second trial, only the solutions oK and Co were supplied in one replication and lesions were determined at 5 and 22 dai.Supplying plants with the control solutions caused the largest leaf spots, whereas, with exception of the oP solution, the otherways of host nutrition significantly retarded disease development in the intact plants as well as in the segments compared with the control The most drastic impact was caused by the oN - 76 % and oK - 59.9 % treatment in the Int variants. Whereas inboth trials differences between the various nutrition treatments were significant at 5 dai, this could not be verified in the corresponding leaf segment variants in which the mean data obtained were significantly about 38 % lower than in the Int variant. Correlation analysis showed that there was no significant association between symptom expression caused by different nutrition in intact and detached host tissue when the data of each of the 5 dai treatment groups were included in the calculation, but when the data of all treatment series, including the 22 dai group in the second trial, were involved, a correlation coefficient of r = 0.61 could be calculated, indicating a relatively close association in affecting symptom expression between livingand rapidly senescing host tissue. Symptom expression focussing on the impact of mineral elements, the putative relevance of some processes of the nitrogen and carbohydrate metabolism and of physiologic stress situations in the host as well as some special requirements in resistance studies deduced from the experimental results are the main objectives in the discussion. 收起