The effects of ultraviolet-B (UV-B: 290–320 nm) radiation on blister blight disease of tea (Camellia sinensis)

Sunlight is known to reduce the incidence of blister blight disease of tea, caused by Exobasidium vexans . The effects of the ultraviolet-B (UV-B: 290–320 nm) component of solar radiation on the disease and the development of E. vexans were studied in the field in Sri Lanka using UV-screening filter materials held over a commercial crop. Exclusion of UV-B radiation by Polyester, which reduces fluxes in the UV-B region by approximately 75–85%, increased both the number of translucent spots (immature sites of infection) and number of sporulating blisters (mature sites of infection), but it had little or no effect on the sporulation of the pathogen. When basidiospores were artificially inoculated on leaves, and were exposed to full or filtered solar radiation, their survival and germination increased when UV-B wavelengths were removed; significant differences were found 62 h after inoculation. However, UV-B did not affect the extension of germ tubes. This study indicates that the UV-B component of solar radiation plays an important role in the natural regulation of blister blight disease in the field.     

Development of a powder formulation of Pseudomonas fluorescens for control of rice blast

Pseudomonas fluorescens strain Pf1, inhibitory to the growth of the rice blast pathogen Pyricularia oryzae in vitro , was developed as a talc-based powder formulation. When rice seeds were treated with this formulation, the bacteria spread to roots, stems and leaves of the plants and protected against leaf infection by P. oryzae . When applied as a foliar spray, the bacteria survived on the leaves. The powder formulation controlled leaf blast under greenhouse conditions. In tests as a seed treatment and foliar spray in four field trials it effectively controlled the disease and increased grain yield.     

江苏某地区稻虾蟹综合种养模式下养殖水和产品中农药残留与风险评价

为掌握江苏省某地区稻田综合种养基地内（“稻-蟹”及“稻-虾”）养殖水环境及水产品中的农药残留特征与生态风险及健康风险,利用三重四极杆气质联用仪（GC-MS/MS）,选择6个养殖区,根据生长周期,跟踪监测养殖水环境及同期水产品（虾、蟹）中208种农药残留情况,并根据商值法对养殖水环境进行生态风险评价,利用食用安全风险指数对水产品进行食用安全分析。结果表明：综合种养模式下,水环境中检出农药的主要类型为除草剂、杀菌剂、植物生长调节剂等,平均质量分数为0.33 μg·L^-1,同时有少量杀虫剂、杀螨剂、增效剂有检出;在整个生长周期内,稻虾、稻蟹农药残留的主要类型为除草剂、杀菌剂、杀虫剂和植物生长调节剂,平均质量分数为6.1 μg·kg^-1 （以湿质量计）。养殖水环境中农药主要来源于养殖前期环境中残留或外源性污染,随着养殖时间延长,农药含量整体趋向于减少,通过对养殖水环境生态风险进行分析,发现各抽样点位联合风险商值（RQ）均在0~1之间,属于中风险,对环境仍具有一定的压力,除草剂等类型农药应引起重视;在监测周期内,水产品中大部分农药的残留量逐渐减少直至未检出,仅有部分点位杀菌剂有少量存在,通过对同期虾、蟹的健康风险进行分析发现,平均食品安全指数远小于1,农药残留的食品安全风险可以接受。     

THE ERROR IN PREDICTING PASTURE DRY–MATTER DIGESTIBILITY FROM FOUR DIFFERENT METHODS OF ANALYSIS FOR LIGNIN

The lignin content of 50 samples of five grasses of known in vivo digestibility were determined by the methods of Armitage, van Soest and two modifications of the van Soest technique. The error in predicting DM digestibility varied from ±3.1 for tbe Armitage metbod to ±5.0 for the van Soest method. This error compares nnfavourably witb ±2.1 previonsly obtained on tbe same samples with the in vitro technique of Tilley and Terry.     

In memoriam Julius Roth

Ohne Zusammenfassung