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Effects of foliar- and root-applied silicon on the enhancement of induced resistance to powdery mildew in Cucumis sativus 总被引:3,自引:0,他引:3
Two cucumber ( Cucumis sativus ) cultivars differing in their resistance to powdery mildew, Ningfeng No. 3 (susceptible) and Jinchun No. 4 (resistant), were used to study the effects of foliar- and root-applied silicon on resistance to infection by Podosphaera xanthii (syn. Sphaerotheca fuliginea ) and the production of pathogenesis-related proteins (PRs). The results indicated that inoculation with P. xanthii significantly suppressed subsequent infection by powdery mildew compared with noninoculation, regardless of Si application. Root-applied Si significantly suppressed powdery mildew, the disease index being lower in Si-supplied than in Si-deprived plants, regardless of inoculation treatment. The resistant cultivar had a more constant lower disease index than the susceptible cultivar, irrespective of inoculation or Si treatment. Moreover, with root-applied Si, activities of PRs (for example peroxidase, polyphenoloxidase and chitinase) were significantly enhanced in inoculated lower leaves or noninoculated upper leaves in inoculated plants of both cultivars. Root-applied Si significantly decreased the activity of phenylalanine ammonia-lyase in inoculated leaves, but increased it in noninoculated upper leaves. However, Si treatment failed to change significantly the activity of PRs in plants without fungal attack. Compared to the control (no Si), foliar-applied Si had no effects either on the suppression of subsequent infection by P. xanthii or on the activity of PRs, irrespective of inoculation. Based on the findings in this study and previous reports, it was concluded that foliar-applied Si can effectively control infections by P. xanthii only via the physical barrier of Si deposited on leaf surfaces, and/or osmotic effect of the silicate applied, but cannot enhance systemic acquired resistance induced by inoculation, while continuously root-applied Si can enhance defence resistance in response to infection by P. xanthii in cucumber. 相似文献
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使用芳氧基乙酸万酯类化合物AoBe处理不同生育期春小麦,在低浓度条件下有促进幼苗生长、提高田间出苗率、刺激增产等生理作用,在高浓度条件下有抑制生长和致死作用。可见,AoBe具有植物生长调节剂的基本作用特性。AoBe刺激增产作用的适宜处理时期和浓度范围是:浸种和挑旗期为0.01ppm,分蘖期为0.1ppm,拔节期为1 ppm,抽穗期为100ppm左右。以0.01ppm浸种和0.1ppm在分蘖期喷施为最佳组合。1000ppm处理春小麦种子则表现为致死作用。 相似文献
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2007年4月21日晚8时许,河北省衡水市景县温城乡发生特大杀人案,两户居民共被杀死3人,重伤1人。接指令后,河北省泊头市公安局警犬队队长申俊荣立即带领队员曹健携警犬"虎子"、"芳芳"赶 相似文献
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