Comprehensive Microbial Study on Biocide Application as Vase Solution Preservatives for Cut ‘Cherry Brandy’ Rose Flower

Abstract

Disturbance in water relations is the major causes of vase life reduction and senescence in cut flowers This problem is mainly due to microorganism proliferation in the vase solution which leads to vascular occlusion and reduction in solution uptake by cut flowers. Therefore a comprehensive study was conducted to evaluate the biocidal effect of nano silver particles (NSP) and compare it with some previously applied biocides. Roses (cv. Cherry Brandy) were treated in a completely randomized design with: colloid of NSP, citric acid, aluminum sulfate, hydroxyquinoline citrate (HQC), calcium hypochlorite, sodium hypochlorite (NaOCl), tap water, or sterilized distilled water as vase water or solution. Longest vase life was observed in flowers treated with nano silver particles, aluminum sulphate and citric acid, respectively. Nano silver particles, HQC and calcium hypochlorite were the most effective treatments in controlling microbial population followed by aluminum sulfate as the second effective treatment. Nano silver particles, HQC and calcium hypochlorite completely inhibited the microbial growth during the first six days of experiment. Moreover, aluminum sulfate retarded microbial growth, proliferation and growth rate more efficiently than others. Each treatment allowed proliferation of a specific microbe. In general, two yeasts, six fungi, and 26 bacterial colonies were isolated from different vase solutions. Among the isolated fungi, one isolate was <em>Trichoderma harzianum</em> and the five other were different strains of <em>Fusarium solani</em>. Identified bacterial isolates were <em>Bacillus sp.</em>, <em>Coccus spp.</em>, <em>Streptomyces sp.</em>, <em>Pectobacterium sp.</em>, <em>Burkholderia sp.</em>, and <em>Pseudomonas sp</em>. <em>Bacillus</em> was the most wide spread microorganism in most treatments. Identified <em>Bacillus sp.</em> isolates were <em>B. polymexa</em>, <em>B. subtilis</em>, <em>B. megaterium</em> and <em>B. circulans</em>. Since nano silver significantly improved vase life and effectively controlled microbial proliferation in vase solution, our results suggest that nano silver application could be considered as a biocidal preservative solution for rose cut flowers.