植物健康的综合管理(三)——正确使用土壤和基质

植物健康综合管理系统（IpHM）在保证根系健康生长方面确实起到了作用。这就对种植者提出了挑战。植物营养调节、水分管理、根／冠生长管理的成败取决于是否有健康的根系和成分配比适当的栽培基质。[编者按]     

Preharvest applications of growth regulators and their effect on postharvest quality of table grapes during cold storage

Over 54,600 ha of table grapes (Vitis vinifera), mainly cvs. ‘Thompson Seedless’, ‘Flame Seedless’ and ‘Redglobe’, are planted in Chile. Almost the entire production is exported to the USA, Europe, Asia, or one of several Latin American countries, which typically requires 15–40 d of maritime transportation. During this period, several physical, physiological, and pathological factors cause table grape deterioration. Because berry size is the main quality factor in international markets, farmers often overuse the growth regulators, gibberellic acid (GA₃) and forchlorfenuron (CPPU), in an effort to increase berry size. We examined the effect of preharvest growth regulators on seedless (‘Thompson Seedless’, and ‘Ruby Seedless’) and seeded (‘Redglobe’) table grape cultivars during cold (0 °C) storage plus a shelf life period of 3 d at 20 °C. The overuse of GA₃, eight instead of two GA₃ applications on Thompson Seedless, and the use of one GA₃ application on Redglobe and ‘Ruby Seedless’, increased berry pedicel thickness and lowered cuticle content but induced shatter and predisposed grapes to gray mold caused by Botrytis cinerea. In contrast, CPPU increased berry pedicel thickness and cuticle content but did not increase shatter or gray mold incidence. Clusters that were subjected to overuse of combined GA₃ and CPPU were highly sensitive to shatter, had the thickest pedicel, and developed a high gray mold incidence during cold storage. Hairline, a fine cracking developed during cold storage, was induced on ‘Thompson Seedless’ and ‘Ruby Seedless’ by growth regulators, but no hairline occurred on ‘Redglobe’ table grapes. Therefore, berry quality during cold storage is greatly influenced by growth regulator management in the vineyard.     

磷对奶牛红细胞膜脂质的影响

对１５例临床上有明显低磷血症的奶牛血清磷、红细胞膜脂质成分进行了测定。结果表明，低磷血症奶牛血清磷、红细胞膜磷脂明显降低；红细胞膜胆固醇及膜胆固醇／磷脂摩尔比值（ｎｃｈ／ｎｐｌ）明显升高，与健康对照组牛相比差异极显著（Ｐ＜０．０１）；直线相关分析表明，血清磷与红细胞膜磷脂之间呈极显著正相关（ｒ＝０．９１７，ｙ＝１０．８５２ｘ＋３．１９６，Ｐ＜０．０１）；与红细胞膜胆固醇以及ｎｃｈ／ｎｐｌ之间分别呈显著负相关（ｒ＝－０．９４０，ｙ＝２．８５０ｘ－１．０７２，Ｐ＜０．０１；ｒ＝－０．９２０，ｙ＝１．９６８ｘ－１．４０１，Ｐ＜０．０１）。此外，红细胞膜微粘度与膜磷脂之间呈显著负相关（ｒ＝－０．９５４，ｙ＝１９．１２２ｘ－４．３８４，Ｐ＜０．０１），而与膜胆固醇以及ｎｃｈ／ｎｐｌ之间呈显著正相关（ｒ＝０．９８８，ｙ＝０．９２７ｘ＋０．９６４，Ｐ＜０．０１；ｒ＝０．９７８，ｙ＝－０．２９３ｘ＋１．１１３，Ｐ＜０．０１）。结果表明，磷是红细胞膜脂质成分改变的先决因素，而后者又是红细胞膜流动性及膜结构、功能发生变化并导致膜损伤的一个重要因素。     

Acid-induced autoagglutination found in chicken pathogenic Escherichia coli strain.

Chicken pathogenic Escherichia coli strains were found to autoagglutinate in a static culture of trypticase soy broth (TSB). One strain, designated PDI-386, was further studied for its autoagglutinating property. Acidity in the cultured medium caused by glucose degradation induced the autoagglutination. The bacterial cells grown in a glucose-free L-broth could be aggregated by adding acid, which suggests a potentiality of autoagglutination of the strain grown in the L-broth. The autoagglutinating parent (Agg) formed small colonies with irregular edges like rough colonies on the TS agar, whereas its non-autoagglutinating variant (Nag) formed larger smooth colonies with a perfectly round edge. The Nag colony was easily generated from the Agg colony on the TS agar. The autoagglutinating property was very unstable when the bacteria was passed in the TSB, but rather stable in the L-broth. Under electron microscope, the Agg were found to possess pili of more than 20 microns in length. However, the phenotypic expression of autoagglutination did not correlate with that of mannose-sensitive hemagglutination against guinea pig erythrocytes. Incubation of the Nag in the L-broth at room temperature for more than 10 days provoked the reversion of the autoagglutination. There was no difference between the Agg and the Nag in terms of surface hydrophobicity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of membrane proteins and LPS, and plasmid profiles. The virulence of the Agg was higher than that of the Nag. The autoagglutination property is, however, so unstable that the pathogenicity of E. coli isolates from chickens should be carefully evaluated.