Uses of 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate and Terbutryn as algaecides in low-density polyethylene mulching films for agricultural applications

Abstract

The aim of this work concerned the performances and limitations of uses of two commercial biocides, namely 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate and N²-tert-butyl-N⁴-ethyl-6-methylthio-1,3,5-triazine-2,4-diamine (Terbutryn), in low-density polyethylene mulching film for agricultural application. The effects of type and algaecide concentration as well as aging deterioration of low-density polyethylene film surfaces were studied in relation to the mechanical, physical, and antialgal properties of the low-density polyethylene films. For antialgal evaluation, disk diffusion test and chlorophyll-a measurement technique were carried out on Chlorella vulgaris, a single-cell green algae, and Phormidium angustissimum, a blue-green algae. The results suggested that adding 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate or Terbutryn tended to slightly increase the lightness value (L*) of specimens, but did not affect the film mechanical properties. The disk diffusion test indicated that only Terbutryn at 600–1000 ppm resulted in clear zone development against C. vulgaris for low-density polyethylene film specimens. Regarding the quantitative study by chlorophyll-a measurement technique, the antialgal activities of low-density polyethylene films gradually improved with increasing algaecide concentrations. Terbutryn appeared to show more effective antialgal efficacy than 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate. Under aging deterioration, Terbutryn-low-density polyethylene films showed less degradation of mechanical properties than neat low-density polyethylene films. However, the antialgal activity of Terbutryn-low-density polyethylene films at various algaecide concentrations was reduced under both accelerated UV weathering and natural outdoor exposure.