The potato (Solanum tuberosum L.) is one of the most important agricultural plants in the world. Today, potato is the fourth most important food crop in the world after wheat, rice and corn. It is propagated predominantly by asexual method (tubers and minitubers). Howev More
The potato (Solanum tuberosum L.) is one of the most important agricultural plants in the world. Today, potato is the fourth most important food crop in the world after wheat, rice and corn. It is propagated predominantly by asexual method (tubers and minitubers). However, propagation by true seed is primarily used for breeding purposes (enhancement of breeding populations) and genetic studies. The traditional methods for asexual propagation of the plant face important problems including contamination of tubers and plants and decreased crops. Therefore, the seed tubers can be replaced by micrutubers produced by tissue culture. In this study solid and culture media used for produce of sterile plantlets and microtuberization. The aim of this study is search about effect of different concentrations of NH4NO3 and KNO3 in media culture Invitro in histological/ cellular variations of the microtubers. The concentrations of 0, 1/2, 1, 3/2 and 2 times more than standard concentrations of the above mentioned compounds in MS medium were used in separate induction media. The results showed that the alternating light and darkness is more suitable for the variety Agria and the samples kept in absolute darkness demonstrated no microtuberization in this study. Sections for light microscopy were prepared from microtubers in each sample after their dimensions were measured and morphological studies carried out. The aim was to study the histological aspects of samples. The number of cell rows, the dimensions of the cells and the starch content of the parenchymal tissues of microtuber's pulp and the cortex were analyzed. The results again showed significant variations in histological features of the microtubers developed in media containing different concentrations of macronutrients. In this study, KNO3 with concentrations of 1.5 times more than standard concentration in MS medium yielded maximum number of cell rows and maximum starch granules content which were proportional to the average dimensions of microtubers. NH4NO3, with concentrations of 1/2 to 1 time more than standard concentrations in MS medium yielded a better differentiation of parenchymal tissues than other concentrations.
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The potato (Solanum tuberosum L.) is one of the most important agricultural plants in the world. It is propagated predominantly by asexual methods. The traditional methods for asexual propagation of the plant faced important problems. Therefore, the seed tubers can be r More
The potato (Solanum tuberosum L.) is one of the most important agricultural plants in the world. It is propagated predominantly by asexual methods. The traditional methods for asexual propagation of the plant faced important problems. Therefore, the seed tubers can be replaced by micro tubers produced by tissue culture. The aim of this study is search about effect of different concentrations of CaCL2 and MgSO4 in media culture In vitro in histological - cellular variations of the microtubers. In this study solid and liquid MS media were used to prepare sterilized seedlings and micro tuberization.The concentrations of 0, 1/2, 1, 3/2 and 2 times more than standard concentrations of the mentioned compounds in MS medium were used in separate induction media . Induction was done in the alternating photoperiod. In order to the developmental and anatomical studies cross sections of microtubers was prepared and studied by light microscopy.The number of cell rows, the dimensions of the cells and the starch content of the parenchymal tissues of microtuber were analyzed. the results showed significant variations in histological features of the microtubers developed in media containing different concentrations of macronutrients. CaCL2 with concentrations of 0.5 to 1 time more than standard concentration in MS medium yielded maximum number of cell rows and maximum starch granules content. However, the presence of a minimum amount of magnesium is essential for the formation of the micro tubers. But there is no statistically significant effect on cellular changes of microtubers and starch content.
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با توجه به نیاز افزایش راندمان انتقال حرارت در سیستم های حرارتی بخصوص در سیستم هایی با ابعاد میکرو و نانو وجود ایده استفاده از نانوسیالات در تجهیزات انتقال حرارت برای بهبود عملکرد آن ها بسیار مناسب می باشد. دراین مقاله جریان و انتقال حرارت جابجایی اجباری نانوسیال آ More
با توجه به نیاز افزایش راندمان انتقال حرارت در سیستم های حرارتی بخصوص در سیستم هایی با ابعاد میکرو و نانو وجود ایده استفاده از نانوسیالات در تجهیزات انتقال حرارت برای بهبود عملکرد آن ها بسیار مناسب می باشد. دراین مقاله جریان و انتقال حرارت جابجایی اجباری نانوسیال آب-مس در یک میکرو لوله در رژیم لغزشی تحت شار حرارتی ثابت در مقادیر رینولدز پایین به صورت عددی موردبررسی قرار می گیرد. شرط مرزی لغزش و پرش دمایی در دیواره برای اولین بار مورداستفاده قرار گرفت و نتایج به‌صورت پروفیل های سرعت و دما و محاسبه مقادیر ناسلت و افت فشار موضعی در ناحیه ورودی و توسعه‌یافته کانال ارائه‌شده است. اثر لغزش و استفاده از نانو سیالات بر انتقال حرارت در میکرو لوله بررسی گردیده است.نتایج نشان می دهد که عدد ناسلت در ناحیه توسعه‌یافته با افزایش لغزش در دیواره، افزایش و میزان افت فشار در این ناحیه کاهش می یابد و نتایج در این ناحیه مستقل از عدد رینولدز جریان هست. در ناحیه ورودی افزایش عدد رینولدز جریان نیز باعث افزایش این مقادیر در این ناحیه می-گردد. همچنین در این پژوهش مشاهده گردید افزودن نانو ذرات به سیال باعث افزایش انتقال حرارت جریان گردیده اما این مقدار ناچیز است.
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