库尔勒香梨萼端黑斑病发生的原因

Causes of occurrence of the calyx-end black spot on Korla fragrant pear

2007-2009年,在新疆库尔勒地区,香梨在贮藏期发生一种此前极少发生的病害,即萼端黑斑。为了探明该病害的发生原因,对香梨健康果与萼端黑斑果果实品质、矿质元素等方面进行了比较研究,同时对黑斑病果进行病原学鉴定。结果表明,香梨萼端黑斑病果实较健果可溶性固形物含量低,且病果中公梨(花萼宿存或未脱落净的)所占比例高达80%;矿质元素测定结果表明,病果中Ca含量低于健果,而N/Ca、K/Ca均高于健果,且果实花萼端钙含量最低,氮含量以及N/Ca、K/Ca最高。柯赫氏证病法结果显示,分离得到的枝孢霉属(Cladosporium cladosporioides)和链格孢属(Alternaria alternata)真菌为非致病菌。初步认为,库尔勒香梨萼端黑斑病是一种由于果实品质下降和N/Ca、K/Ca失调及缺钙引起的生理性病害。

A new disease （the calyx end black spot of Korla pear） was observed during storage period in Korla,Xinjiang from 2007 to 2009. To explore the reasons for the occurrence of the disease, the pear’s quality and the content of mineral elements between the normal pears and diseased pears were compared and pathogens from the diseased pears were identified as well. The results indicated that the diseased pears had a lower content of soluble solid, the percentage of male fruit was up to 80%, and the content of Ca was also lower than that of the normal pears. The lowest calcium content and the highest nitrogen content were observed in the calyx end, and the ratio of N/Ca and K/Ca were also highest in the calyx end. The results of koch＇s rules showed that Cladosporium and Alternaria isolated from the diseased part were nonpathogen, therefore, the calyx-end black spot of Korla pear was a physiological disease mainly due to decline of quality, inblance of N/Ca,K/Ca and the lack of Ca in pear.