Chlorobenzyl Cyclopentyl-3-phenylurea Effects on Heterocystous Filamentous Cyanobacteria Westielliopsis prolifica Janet

摘要

An extensive usage of fungicides in various tropical and subtropical countries to control various fungal infections adversely affects the growth of microflora, including cyanobacteria. Toxic effect of 1-(4-chlorobenzyl)-1-cyclopentyl-3-phenylurea (trade name pencycuron), a non-systemic protective fungicide recommended for controlling sheath blight of rice on Westielliopsis prolifica, an abundant cyanobacterium found in rice (Oryza sativa L.) fields, was studied under laboratory conditions. Photopigments and stress metabolites like carbohydrates, proteins, amino acids and phenol content were measured across 16 days at 4-day intervals. Nitrate reductase and glutamine synthetase activities were also measured. The results revealed that pencycuron exerted unfavorable effects on the selected cyanobacterium at 100 and 200 ppm. Chlorophyll-a, carotenoids, phycoerythrin, amino acid, and enzyme activities were more adversely affected by pencycuron than other parameters, such as total carbohydrates, proteins, and phenols. The results support the suggestion that the physiological mode of pencycuron toxicity to W. prolifica is related to its interference with the metabolic and enzymatic reactions. For this reason, use of pencycuron should be prohibited in rice fields.