无机营养N,P,Ca和K对黑斑病菌侵染甘蓝幼苗的影响

Manifestation of Black Spot Disease(Alternaria brassicicola) in Young Cabbage Plants Grown in Nutrient Solutions without N,P,Ca,and K

将甘蓝幼苗分别培养在缺N(oN)、缺P(oP)、缺Ca(oCa)或缺K(oK)的不完全营养液中,培养56 d后分别于离体(Seg)和非离体(Int)叶片上接种黑斑病菌,以N,P,Ca和K营养素齐全的全营养液为对照,通过调查不同营养液处理后甘蓝叶片黑斑病的病斑大小,探讨N,P,Ca和K等无机营养素对黑斑病菌侵染甘蓝幼苗的影响。试验分2部分完成:第1部分缺N,缺P和缺Ca 3个处理同时进行,试验结果表明,不同营养液培养的甘蓝叶片黑斑病病斑大小有显著差异,顺序为对照>缺P>缺Ca>缺N处理;而在对照、缺P和缺Ca处理中,同一处理的非离体叶片病斑明显大于离体叶片病斑,缺N处理情况则相反。第2部分缺K处理的试验中,接种后5 d的病斑明显小于对照,非离体叶片与离体叶片接种后的病斑分别比对照小53%和14%;而缺K处理的离体叶片病斑显著比非离体叶片大(37%),并且病情随着接种后时间的延长而加重,在接种22 d后植株叶片和离体叶片的病斑大小趋于平衡。相关性分析表明,接种后5 d甘蓝幼苗活体组织和衰老组织的症状表达没有明显的相关性,但从试验2接种后22 d以及整个试验所有数据的结果分析,两者之间存在一定的相关性,相关系数达r=0.61。

In two experiments young cabbage plants in the 4/6-leaf-stage were supplied about eight weeks with nutrient solutions without nitrogen （oN）, phosphorus （oP）, calcium （oCa）, and potassium （oK） in order to investigate the impact of deficiency of essential major elements on the pathogenesis of black spot disease caused by Ahernaria brassicicola. Intact （Int） and detached （Seg） segments from one of the fully expanded leaves were used for inoculation. Lesion size was the parameter of the pathogenic activity. In experiment 1 deficiency nutrient solutions oN, oP and oCa were tested simultaneously in four replications. Supplying plants with the control solution （ck） that contained all mineral elements essential for plant growth caused the largest leaf spots whereas all other forms of host nutrition retarded the development of lesions significantly in the Int as well as Seg trials ranging oN 〉 oCa 〉 oP. In experiment 2 the nutrient solution oK was supplied and lesions were determined at 5, 7 and 22 d. At the fifth day after inoculation differences between the various nutrition forms were significant. In comparison to the control series cklnt and ckSeg , the oK solutions restricted the progress in lesion size about 53% respectively 14%, whereas on the oKSeg series the spots were remarkable larger （37%） comoared with the oKInt series. Lesion sizes increased with time,but at 22 d differences between the various forms of nutrition in both Int and Seg tissue became near identical. Correlation analysis showed that there was no signifi- cant association between symptom expression caused by different nutrition in intact and senescing host tissue, but when the data of all treatment series, including the 22 d 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 living and rapidly senescing host tissue.