اثر عصاره گیاه اسپند بر جمعیت باکتریایی محلول نگهدارنده و عمرگلجایی ارقام ‘Stanza’ و ‘Pink Elegance’ گل شاخه بریده ژربرا

تیمار محلول‌های نگهدارنده گل‌هایبریده با مواد باکتری‌کش یکی از راه‌های کاهش انسداد آوندی و افزایش عمرگلجایی می‌باشد. در این پژوهش عصاره آبیالکلی گیاه اسپند در غلظت‌های صفر، 0.25، 0.5، 0.75 و 1 درصد به مدت 3، 6 و 9 روز در دمای 1±22 درجه سلسیوس و رطوبت نسبی 70 درصد بر جمعیت باکتری‌های محلول نگهدارنده و برخی خصوصیات کیفی رقم‌های ‘stanza’ و ‘pink elegance’ گل بریده ژربرا به‌صورت آزمایش فاکتوریل بر پایه طرح کاملاً تصادفی با چهار تکرار در بهار سال 1397 در دانشگاه ایلام مورد مطالعه قرار گرفت. نتایج نشان داد که اثر بازدارندگی عصاره‌ها بر رشد باکتری‌های گرم مثبت بیشتر از باکتری‌های گرم منفی بود و با افزایش غلظت عصاره اسپند، اثر بازدارندگی نیز افزایش یافت. همچنین تحت تاثیر تیمارها، رقم ‘stanza’ نسبت به رقم‘pink  elegance’از کیفیت بهتر و عمر گلجایی بیشتری برخوردار بود. با افزایش مدت زمان نگهداری گل‌ها، کیفیت آن‌ها کاهش یافت، ولی در مرتبه اول غلظت 0.25 و سپس 0.5 درصد عصاره اسپند علاوه بر کاهش جمعیت باکتری‌ها در محلول گلجایی و انتهای ساقه، باعث کاهش نشت یونی ساقه و گلبرگ، حفظ کیفیت (تغییر رنگ محلول گلجایی، ساقه و گلبرگ)، وزن تر نسبی، قطر ساقه، مواد جامد محلول و حفظ آنزیم‌های کاتالاز و فنیل آلانین آمونیالیاز نسبت به نمونه‌های شاهد شدند و عمر گلجایی گل‌های ژربرا را افزایش دادند. غلظت‌های 0.75 و یک درصد اگرچه جمعیت میکروبی محلول گلجایی و انتهای ساقه را کاهش دادند ولی در حفظ کیفیت و عمر گلجایی گل‌های ژربرا اثر قابل توجهی نداشتند که می‌تواند به دلیل افزایش غلظت مواد آللوپاتیک در آن‌ها باشد.

Effect of Harmel Extract on Bacterial Population in Vase Solution and Vase Life of ‘Stanza’ and ‘Pink Elegance’ Cultivars of Gerbera Cut Flower

Abstract Background and ObjectivesGerbera is one of the important cut flowers in the floriculture industry, but it is sensitive to early wilting and neck bending which reduce its postharvest vase life. In cut flowers, water deficits are created when transpiration is more than water absorption. Therefore, petal wilting and neck bending increase in these flowers. These conditions are mainly due to occlusion of the vascular bundle, which can occur in different ways, such as the activity of pathogenic bacteria and other microorganisms in vascular bundle. In recent years, due to the adverse effects of chemical antimicrobial compounds on human health and the environment, many studies have been conducted to find replacement materials to maintain the quality and vase life of cut flowers in postharvest. Therefore, in this study, the effect of different concentrations of harmel aqueousalcoholic extract (Peganum harmala L.) on bacterial population and vas life of ‘Stanza’ and ‘Pink Elegance’ cultivars of Gerbera cut flower were studied. Materials and MethodsThe effect of concentrations 0, 0.25, 0.5, 0.75 and 1% of the aqueousalcoholic extract of Harmel plant was studied in a factorial experiment based on completely randomized design with four replications. At harvest time, 3, 6 and 9 days after harvest (at 20 °C and 70% relative humidity), the effect of treatments on the bacterial population of the vase solution and end stem, vase life and some characteristics of ‘Stanza’and ‘Pink Elegance’ Gerbera cut flowers were studied. ResultsThe results showed that the inhibitory effect of harmal extracts on grampositive bacteria was higher than gramnegative bacteria. Also,‘Stanza’cultivar had better quality and longer vase life than ‘Pink Elegance’ cultivar. By increasing the vase life of flowers, the quality of these flowers decreased. In the first place, however, concentrations of 0.25% and then 0.5% of the harmal extract performed better than other treatments in various aspects: first, they reduced the bacterial solution, stem end, and electrolyte leakagein stem and petals; second, they preserved quality (discolored of vase solution, discolored of petals and stem), relative fresh weight, stem diameter, totalsolublesolids, catalase activity and phenylalanine ammonia lyase activity; and finally, they increased vase life of gerbera flowers in both cultivars. Concentrations of 0.75% and 1% increased allelopathic substances in cut flower. While these treatments decreased the bacterial population in vase solution and stem end, they did not have a significant effect on the quality and vase life of gerbera cut flowers.  DiscussionThe results of this study showed that the different concentrations of harmal extract significantly reduced the growth of microbial agents, including the bacterial population, but by increasing the concentration of the harmal extract, the allelopathic effects of this plant extract on gerbera cut flowers were harmful and did not affect their vase life and quality. Therefore, the concentration of 0.25% then 0.5% reduced the bacterial populations in vase solution and stem end of cut flowers and preserved the quality and vase life of ‘Stanza’ and ‘Pink Elegance’ cultivars. Therefore, the use of low concentrations of the harmel aqueousalcoholic extract is recommended to reduce the microbial population of the vase solution and maintain the quality and vase life of the gerbera cut flowers.