Treatment with chlorine dioxide extends the vase life of selected cut flowers

The accumulation of bacteria in vase water is often associated with premature senescence in many cut flower species. In the present study, we tested the efficacy of aqueous chlorine dioxide (ClO₂) to extend flower display life by preventing the build-up of bacteria in vase solutions. The addition of 2 or 10 μL L⁻¹ ClO₂ to clean deionized water extended the vase life of Alstroemeria peruviana ‘Senna’, Antirrhinum majus ‘Potomic Pink’, Dianthus caryophyllus ‘Pasha’, Gerbera jamesonii ‘Monarch’, Gypsophila paniculata ‘Crystal’ and ‘Perfecta’, Lilium asiaticum ‘Vermeer’, Matthiola incana ‘Ruby Red’ and Rosa hybrida ‘Charlotte’ flowers by 0.9–13.4 d (7–77%) relative to control (i.e. 0 μL L⁻¹ ClO₂) stems. The beneficial effects of ClO₂ treatment were associated with a reduction in the accumulation of aerobic bacteria in vase water and on cut surfaces of flower stems. ClO₂ treatment was also effective in maintaining or extending the vase life of A. majus ‘Potomic Pink’, Dendrathema × grandiflorum ‘Albatron’, G. paniculata ‘Perfecta’ and M. incana ‘Ruby Red’ flowers even when stems were placed into water containing 10¹¹ CFU L⁻¹ bacteria. The efficacy of 10 μL L⁻¹ ClO₂ in vase water containing 0.2 g L⁻¹ citric acid and 10 g L⁻¹ sucrose to extend the display life of G. jamesonii ‘Lorca’ and ‘Vilassar’ flowers was equal to or greater than other tested biocides (i.e. aluminum sulfate, dichloroisocyanuric acid, 8-hydroxyquinoline sulfate, Physan 20™, sodium hypochlorite). Taken collectively, the results of the present study highlight the potential of aqueous ClO₂ for use as an alternative antibacterial agent in flower vase solutions.     

Effect of S-carvone on vase life parameters of selected cut flower and foliage species

Insufficient water uptake by cut flowers and foliage species is often due to stem end occlusion and poor stem hydraulic conductance that involve bacterial growth and/or wound healing. S-carvone has putative antibacterial and anti-wound healing activity. S-carvone (0, 0.318 and 0.636 mM) was evaluated as a vase solution for Acacia holosericea (Mimosaceae), Baeckea frutescens (Myrtaceae), Chamelaucium uncinatum cv. ‘Mullering Brook’ (Myrtaceae) and Chrysanthemum sp. cv. ‘Dark Splendid Reagan’ (Asteraceae). S-carvone was also tested in vitro for activity against a vase solution bacterium. S-carvone at 0.318 and 0.636 mM showed significant (P < 0.05) positive effects on relative fresh weight, solution uptake and/or vase life for B. frutescens foliage and C. uncinatum flowering stems, but did not have positive effects for A. holosericea and Chrysanthemum sp. S-carvone did not suppress vase solution bacterial populations. Moreover, there was no in vitro activity at vase solution concentrations against the specific vase water bacterium, Bacillus cereus. For the two Myrtaceous genotypes, B. frutescens and C. uncinatum, S-carvone apparently extended vase life by inhibiting wound healing.     

A treatment to improve the vase life of cut tulips: Effects on tepal senescence, tepal abscission, leaf yellowing and stem elongation

The vase life of cut tulips (Tulipa spp.) is limited by a combination of leaf yellowing, tepal senescence, and tepal abscission. In many cultivars, moreover, high rates of stem elongation result in stem bending during vase life. In tests with the cvs. Apeldoorn and Frappant, stem bending could be prevented by treatment with ethylene or ethephon. However, these treatments resulted in poor flower opening. The ethephon treatment also resulted in precocious tepal abscission. The negative effect of ethephon on flower opening was overcome by a treatment with gibberellic acid (GA₃). GA₃ also somewhat delayed early leaf yellowing, but did not prevent the early tepal abscission induced by ethephon. The latter problem was overcome by a treatment with benzyladenine (BA). In addition, BA effectively delayed leaf yellowing and also delayed tepal senescence. However, BA produced browning of the lower stem end. This was prevented by the inclusion of calcium ions in the solution. The combination of chemicals (ethephon, GA₃, BA, and calcium ions) was similarly successful in a large number of other tulip cultivars tested. After adaptation of the concentrations the four chemicals were also effective if given as a pulse treatment shortly after harvest.     

HgCl2短时处理对蚕豆叶片光合作用的效应

以不同浓度HgCl₂溶液涂抹蚕豆(Vicia faba L.)叶片30 min后, 测定进入叶片组织的汞含量、叶片的气体交换和叶绿素荧光。随着外施HgCl2溶液浓度的增大, 进入叶片组织的汞含量增加。当HgCl₂溶液浓度高于10 mg L^-1时, 处理显著抑制蚕豆叶片的净光合速率(P_n)和表观光合量子效率(AQY), 且随着浓度增加, 抑制程度也加强。同时, HgCl₂溶液处理能够显著降低PSⅡ光量子产量(DF/ F_m’)和表观光合电子传递速率(ETR), 增加叶片的叶绿素荧光非光化学猝灭(NPQ)。 结果表明, 低浓度HgCl₂短时间处理导致蚕豆叶片P_n降低的主要原因是由于HgCl₂抑制了光合电子传递过程。     

镉离子对水丝蚓超氧化物歧化酶和过氧化氢酶活性的影响

制药废水中普遍含有的镉,即使低剂量环境暴露即可引起肾功能损伤、骨矿密度降低、钙排泄增加及生殖毒性,Cd²⁺对生态环境的恶化已经引起了世界各国的普遍重视。试验首先获得了镉离子对水丝蚓24 h LC₅₀的理论值为0.471 mg/L,在0.415~0.535 mg/L浓度区间选择5个浓度的镉离子处理水丝蚓24 h,检测水丝蚓超氧化物歧化酶(SOD)和过氧化物酶(POD)的变化。结果表明：在不同浓度镉离子胁迫下,水丝蚓SOD和POD活性均发生不同程度的改变,但是两种酶的24 h连续变化趋势相反。说明二者生物学机制不同,在细胞抵抗外来污染物的过程中,可能分别发挥不同的作用。