Effects of Spores and Crude Toxins of Helminthosporium gramineum Rabenh f.sp.echinochloae on the Activity of Defensive Enzymes in Barnyardgrass

[Objective] This study aimed to explore the effects of spores and crude toxins of Helminthosporium gramineum Rabenh f. sp. echinochloae（HGE） on the ac- tivity of defensive enzymes of barnyardgrass [Echinochloa crus-galli （L.） Beauv.]. [Method] The effects of spores and crude toxins of HGE, as well as the mixture of spores and crude toxins on the activity of defensive enzymes in barnyardgrass were determined under laboratory conditions. [Result] Spores and crude toxins of HGE had varying degrees of effects on PAL and POD activity, and no obvious effect on SOD activity in barnyardgrass. In addition, spores and toxins had some similar im- pacts on the defensive enzymes in barnyardgrass. [Conclusion] Since toxins have similar effects on the hosts as spores of fungal pathogen do, they can be a substi- tute for the fungal pathogen in studying the partial pathogenic mechanism of this pathogen due to its complexity in pathogenic process.

土壤湿度对土壤处理除草剂药效的影响研究

室内生测及温室盆栽试验,系统地评价了土壤湿度对除草剂除草活性的影响作用。以稗草作生测材料,在室内采用二次正交旋转组合设计,建立除草剂对稗草抑制率与土壤湿度、除草剂用量之间关系的数学模型;讨论了土壤处理除草剂广灭灵、乙草胺、都尔、丙草胺、大惠利、扑草净、恶草灵、除草通、阿特拉津的药效与用量、土壤湿度的关系。结果表明:除草剂的施用量是除草效果的决定因素,药效随用量的增加而提高;土壤湿度对除草剂的药效影响显著,尤其在用量较低的情况下,随着除草剂用量的增加,土壤湿度对药效的影响降低;除草剂的施用量与土壤湿度之间存在互作效应,因此除草剂的施用剂量与土壤湿度有最优组合;在相同的土壤湿度条件下,对不同除草剂的药效影响不同,且与除草剂的水溶性有关。

禾长蠕孢菌孢子及粗毒素对稗草防御酶系活性的影响

[目的]探讨禾长蠕孢菌(HGE)孢子及其代谢产物粗毒素对稗草主要防御酶系活性的影响。[方法]在室内条件下测定了HGE孢子及其粗毒素对稗草防御酶系[苯丙氨酸解氨酸(PAL)、过氧化物酶(POD)、超氧化物歧化酶(SOD)]活性的影响。[结果]HGE孢子、粗毒素及二者混合处理稗草后,不同程度地影响了稗草PAL、POD的活性,对SOD活性无明显影响,并且孢子和毒素对稗草防御酶系的影响具有相似性。[结论]病原真菌孢子和毒素对寄主的作用具有一定的相似性,基于病原菌致病过程的复杂性,毒素可以替代病原菌研究其部分致病性作用机理。