تخمین زده شده که 20 تا 25 درصد از تمام سبزفرش ها (چمن ها) تحت تاثیر سایه ناشی از ساختمان ها یا درختان بلند، قرار می‌گیرند. بنابراین سایه از طریق اثر بر شدت، کیفیت و طول مدت تابش بر رشد گیاه اثر می گذارد. با توجه به اهمیت سبزفرش ها در زیبایی محیط پیرامون بشر تاکنون پژوهش های کافی برای شناخت ویژگی های مورفوفیزیولوژیک سبزفرش ها در شرایط طول روز مختلف انجام نشده است. به همین منظور پژوهشی مزرعه ای با هدف اثر طول روز بر برخی ویژگی های مورفولوژیکی و فیزیولوژیکی دو جنس سبزفرش، به صورت طرح کرت های خرد شده در قالب طرح بلوک های کامل تصادفی با چهار تکرار در مزرعه پژوهشی دانشکده کشاورزی بخش علوم باغبانی دانشگاه شیراز انجام شد. طول روز در سه سطح (روز بلند (16 ساعت)، روز متوسط (12 ساعت) و روز کوتاه (8 ساعت)) به‌عنوان فاکتور اصلی و دو جنس سبزفرش (Festuca arundinacea Schreb. و .Cynodon dactylon [L.] Pers) به‌عنوان فاکتور فرعی در نظر گرفته شدند. نتایج نشان داد که روز کوتاه سبب کاهش تراکم پنجه، وزن تر و خشک شاخساره، وزن تر و خشک ریشه و محتوای کلروفیل و نشاسته و افزایش سطح برگ و فعالیت آنزیم های سوپراکسید دیسموتاز، کاتالاز، پراکسیداز و آسکوربات پراکسیداز شد. همچنین نتایج نشان داد که روز بلند سبب افزایش تراکم پنجه، وزن تر و خشک شاخساره، وزن تر و خشک ریشه و محتوای کلروفیل و نشاسته و کاهش سطح برگ و فعالیت آنزیم های سوپراکسید دیسموتاز، کاتالاز، پراکسیداز و آسکوربات پراکسیداز شد. سبزفرش Festuca arundinacea Schreb. در مقایسه با سبزفرش Cynodon dactylon [L.] Pers. مقاومت بیشتری به کاهش طول روز نشان داد. با توجه به امکان افزایش دوره روشنایی در پارک ها و استادیوم ها، در زمان هایی که سبزفرش ها در فصول سرد رنگ زرد به خود می گیرند. افزایش دوره نوری سبب بهبود رنگ سبز و افزایش کارایی در سبزفرش ها می گردد. تفاصيل المقالة

In many parts of Iran high light intensities during summer can induce stress in cut flower production under open field and greenhouse conditions. Despite roses prefer sunny places for optimum growth, but in practice some levels of rough shading is applied in greenhouse production to improve the quality of cut flowers. So, it is useful to find the light intensities under which different rose cultivars produce optimum yield with acceptable market quality. In present study, different light intensities were applied for two rose cultivars of ‘Red One’ and ‘Gulmira’, by shading levels of 1200 (without shading as control), 640, 520 and 240 µmol m-2 s-1, using green plastic nets. The result showed that leaf protein concentration, peroxidase activity, petal anthocyanin concentration and carbohydrate levels were significantly different among shade treatments, as the highest protein concentration was observed in 640 µmolm-2 s-1. The highest concentration of anthocyanin of petals was observed in ʻRed Oneʼ under 520 µmolm-2 s-1. Furthermore, in ʻGulmiraʼ the highest amount of anthocynin was in 520 µmol m-2 s-1, but this was not statistically significant compared to other shading treatments. The highest amount of leaf carbohydrate was in 520 µmol m-2 s-1. The results indicate that shading up to a light intensity of 520 µmol m-2 s-1 is beneficial for quality improvement of these rose cultivars when light intensity is high. تفاصيل المقالة

Abiotic stress conditions can be imposed on plants through either poor water quality or adverse climate condition. These types of stress affect plant growth and development throughout their life cycle. Plants that are tolerant to drought are therefore valuable, and turf grasses have the potential to grow tolerant. Turf grasses provide ground cover and offer multiple benefits, from their aesthetic value which affects our daily lives to their preservation of land against erosion. The objectives of the present work were to find the ideal media for callus induction and regeneration followed by overexpressing the P5CS1 gene encoding proline for improving drought stress resistance in Festuca arundinacea Schreb. The husks of tall fescue seeds were removed and the seeds were then sliced longitudinally. The result of this treatment showed a greater callus induction efficiency in comparison with intact seeds in the culture media. In addition, an increase in regeneration efficiency was observed in media supplemented with 2,4-D along with BAP. The average of G418‒resistant calli obtained in the experiment was around 10%. The heterologous transformation of P5CS1 in F. arundinacea background was confirmed by PCR and the transient Gus assay. More than 90% of calli expressed the uida gene which can most probably convey resistance to drought stress. تفاصيل المقالة

The natural tragacanth gum, the sap of Astragalus gummifer, has been successfully used as a gelling agent in tissue culture media for in vitro shoot development and proliferation of miniature rose and carnation. Shoot development of nodal segments excised from greenhouse grown plants, was investigated on MS medium solidified with either 2.5, 3.0, 3.5 and 4.0% tragacanth or 0.8% agar as control. The media solidified with tragacanth were more transparent than the media solidified with agar. Viscosity of the tragacanth-gelled media was less than the agar-gelled media, and therefore, putting the explants on the media sometimes resulted in submersion of them into the media and some cases of development of hyperhydric shoots were observed. To increase the firmness of the media, the combinations of agar (0.2 and 0.3%) and tragacanth (2 and 3%) were used. The viscosity of the combinatory media was as good as the medium containing only 0.8% agar (control). Moreover, the explants productivity and growth obtained in these combinations were better than those recorded on the control medium. Being a plant product, biodegradable and environmental friendly, and 10 times cheaper than agar, tragacanth gum would definitely be useful for reducing costs, particularly in the plant tissue culture industry. تفاصيل المقالة