Lemon grass essential oil improves Gladiolus grandiflorus postharvest life by modulating water relations, microbial growth, biochemical activity, and gene expression

Abstract

Gladiolus (Gladiolus grandiflorus Andrews) is a high-valued bulbous cut flower. However, the shorter postharvest life of the gladiolus, limits its marketing and commercial value. In the present investigation, the effect of lemon grass (LG) essential oil as an antimicrobial agent was studied towards increasing the vase life of gladiolus. The results revealed that as compared to control (distilled water), treatment with a lower concentration of 5 µL L−1 LG essential oil prolonged the vase life of gladiolus up to 11 days (d). Scanning Electron Microscope (SEM) observation indicated that the sample treated with 5 µL L−1 LG essential oil showed intact vasculature, suggesting reduced microbial blockage at the stem end which was further corroborated by microbial count. Biochemical analysis suggested an increased level of total soluble sugars, carotenoid content, lower MDA accumulation, and higher activity of antioxidant enzymes in LG treated flowers. Moreover, transcripts levels of genes associated with senescence viz., GgCyP1 and GgERS1a were downregulated, while expression of GDAD1 and antioxidant genes such as GgP5C5, GgPOD 1, GgMnSOD, and GgCAT1 were upregulated in LG treated cut spikes as compared to control. Among various treatments we have concluded that, the vase life of the gladiolus cut spike was improved along with the relative fresh flower weight and diameter of flower at the lower dose of 5 µL L−1 LG oil in the vase solution. Thus, LG oil as an eco-friendly agent has the potential to extend the postharvest life of cut flowers.

How Sage and Rosemary Essential Oils Regulate Postharvest Senescence and Extend the Vase Life of Cut Gladiolus Spikes

“…Unlike the control spikes, EO-treated ones exhibited a considerable reduction in their H 2 O 2 and MDA levels, which can be justified by the fact of considerable amounts of phenol and antioxidant compounds in the EOs that enable gladiolus florets to alleviate oxidative damage. These results are in agreement with previous reports of using lemongrass essential oil in gladioli [25] and ginger essential oil in Davallia solida [45]. The content of MDA was markedly decreased in gladiolus florets in response to the application of sage or rosemary EOs.…”

“…Similar findings have been reported to extend the vase life of cut gladiolus spikes using natural leaf extracts rich in phenolic compounds [16]. Similarly, a positive role of various EOs in enhancing water relations and limiting bacterial growth has been reported in several plant species, such as using Shirazi thyme EO in gerbera [22], Salvia rosmarinus EO in carnations [23], Mentha piperita EO in gladioli [16], Mentha spicata EO in roses [24] and lemon grass EO in gladioli [25].…”

“…The average daily water uptake was determined as the difference between the solution volume on the initial day (day 0) and daily until day 6. Values were expressed as mL day −1 stem −1 [25].…”

“…Several reports have revealed that the addition of EOs to a vase solution enhanced cut flower longevity and quality. The EOs of different aromatic plants, such as Shirazi thyme in gerbera [22], Salvia rosmarinus in carnation [23], Mentha piperita in gladiolus [16], Mentha spicata in rose [24], and lemon grass in gladiolus [25], have been used to extend the vase life and quality due to their effective antibacterial properties. The EOs of sage and rosemary seem to be effective eco-friendly flower preservatives due to their content of antimicrobial and antioxidant compounds.…”

Peppermint essential oil enhances the vase life of Dendrobium orchids

“…Additionally, nonenzymatic antioxidants such as anthocyanin constitute an endogenous defense against ROS in flower tissues, with anthocyanin also contributing to petal color [ 66 ]. Many studies on cut flowers have demonstrated that natural antioxidants, including essential oils [ 67 , 68 ], salicylic acid [ 69 ], and moringa extract [ 70 ], delay senescence and extend vase life by increasing ROS scavenging activity; this also helps the flower retain anthocyanin content. In peppermint essential oil, the most powerful free radical scavenging compounds are menthone and isomenthone [ [14] , [15] , [16] ].…”