The article about pencycuron (part 1)

Pencycuron at field rate, 2FR and 10FR affected the microbial biomass C, soil ergosterol content and fluorescein diacetate hydrolyzing activity differentially. The DCM amendment did not seem to have any counteractive effect on the toxicity of pencycuron on the microbial variables. Out of four fungicides tested, pencycuron was found most effective to control the sheath blight disease. In the greenhouse, pencycuron inhibited binucleate Rhizoctonia, R oryzae, or R solani in vitro and reduced Rhizoctonia root rot. Pencycuron also inhibited G graminis var tritici strains in vitro and slightly reduced take-all disease in the greenhouse. Moreover, pencycuron seed treatment protected plants against a disease mixture of Rhizoctonia root rot and take-all. Pythium spp were not inhibited by pencycuron in vitro. Pencycuron did not adversely affect seedling emergence, nor did it inhibit rhizosphere colonisation by Pseudomonas fluorescens biocontrol strain 2-79. Pencycuron dissipated at all treatment combinations following first order kinetics and the half-lives ranged between 4.9 to 5.8 days. In lab tests, all chemical treatments reduced the incidence on the seeds of Colletotrichum gossypii, Rhizoctonia solani, Botryodiplodia theobromae and Fusarium spp The best results on the control of C gossypii were obtained with tolylfluanid, pencycuron + tolylfluanid and benomyl. The fungicide pencycuron detached on the control of R solani. The best control of B theobromae was observed when the seeds were treated with pencycuron + tolylfluanid. Fusarium spp was better controlled with pencycuron + tolylfluanid and benomyl. Satisfactory effect of fungicides on the stand was observed. The sensitivity of AG4 isolates to pencycuron was negatively correlated with the mycelial growth at high temperature. Based on such observation and high lipophilicity of pencycuron, the influence of pencycuron on the fluidity of lipid membranes of R solani was examined. The composition ratio of saturated fatty acids such as palmitic acid and stearic acid in R-C was higher than that in Rh-131. On the contrary, linoleic acid, an unsaturated fatty acid, was more abundant in Rh-131. While the fluidity of liposomes prepared with total lipids from R-C remarkably decreased by the application of pencycuron, no significant diminution of membrane fluidity was observed in liposomes from Rh-131. With artificial liposomes prepared from phosphatidylcholines commercially available, the membrane fluidity fluctuated depending on the composition of fatty acids, and the effect of pencycuron on the membrane fluidity was more significant in liposomes composed of higher ratio of saturated fatty acids. It was also found that 14C-pencycuron was bound 3 times more by liposomes that resembled R-C membrane in composition of fatty acids than those mimicked the membranes of Rh-131. Even in the same anastomosis groups, eg, AG4, there are both isolates sensitive and less sensitive to pencycuron. The regeneration of colonies from protoplasts of R-C significantly decreased by the osmotic shock in the presence of pencycuron, while such effect was canceled by washing off the chemical prior to the osmotic shock. However, in Rh-131, the application of the chemical appeared to stimulate the regeneration from protoplasts. Further the measurement of optical density of protoplasts suspensions was performed to elucidate the effect of pencycuron on the osmotic stability of protoplasts in a short period. The optical density of suspensions of R-C protoplasts rapidly declined in a short period of incubation by the osmotic shock in the presence of pencycuron, but the effect on Rh-131 protoplasts was not statistically significant regardless of the presence or the absence of the chemical. 

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