زینب رحیمی

Bio: زینب رحیمی is an academic researcher. The author has an hindex of 2, co-authored 2 publications receiving 4 citations.

تأثیر سطوح شوری و سیلیسیم بر برخی ویژگیهای مورفوفیزیولوژیک گیاه دارویی خرفه (Portulaca oleracea L.)

Abstract: خرفه (Portulaca oleracea L.) گونه‌ای هالوفیت یک‌ساله می‌باشد که می‌تواند به‌عنوان سبزی، علوفه یا گیاه دارویی در شرایط شور مورد توجه قرار گیرد. سیلیسیم دومین ترکیب معدنی بعد از اکسیژن در کره زمین می‌باشد. هر چند هنوز نقش آن در گیاهان کاملا روشن نیست، ولی اثرهای مثبتی بر عملکرد و مقاومت به تنش‌های محیطی در گیاهان داشته‌است. به منظور بررسی تأثیر سطوح مختلف شوری و سیلیسیم بر برخی پارامترهای مورفوفیزیولوژیکی گیاه خرفه آزمایشی به‌صورت کرت‌های خرد شده با چهار سطح شوری (6/0، 7، 14 و 21 دسی‌زیمنس بر متر) و دو سطح سیلیسیم (عدم کاربرد و کاربرد (1 میلی‌مولار سیلیکات سدیم)) و با سه تکرار در سال 1387 در گلخانه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد انجام شد. نتایج نشان داد وزن تر برگ و ساقه، وزن خشک برگ، تعداد برگ و شاخه فرعی در بوته، شاخص سطح برگ، سطح ویژه برگ و ارتفاع ساقه اصلی، تا سطح شوری 14 دسی‌زیمنس بر متر تفاوت معنی‌داری با شاهد نداشتند، ولی در 21 دسی‌زیمنس بر متر کلرید سدیم کاهش معنی‌داری یافتند، در حالی‌که وزن ویژه برگ با افزایش شوری افزایش معنی‌داری یافت. کاربرد سیلیسیم تأثیر مثبت و معنی‌داری در تعداد برگ در بوته، ارتفاع ساقه اصلی و شاخص سطح برگ داشت. نتایج حاصل از این آزمایش نشان داد که این گیاه تا حد زیادی به شوری مقاومت دارد و می‌تواند در مناطق تحت تنش شوری به‌عنوان گیاه دارویی مورد توجه قرار گیرد. همچنین شاید بتوان از سیلیسیم به‌عنوان یک عنصر مفید در افزایش عملکرد گیاهان زراعی و همچنین افزایش مقاومت آنها به تنش‌های محیطی استفاده نمود.

بررسی اثر سطوح مختلف تنش خشکی بر خصوصیات جوانه زنی خرفه (Portulaca oleracea L.)

Abstract: به منظور بررسی تاثیر تنش خشکی بر جوانه زنی گیاه خرفه، آزمایشی در قالب طرح کاملا تصادفی با هشت سطح خشکی(صفر، 0/25-، 0/5-، 0/75-، 0/1-، 1/25-، 1/5– و 1/75-مگاپاسکال) و پنج تکرار در دمای ثابت 25 درجه سانتی گراد و در شرایط کاملا تاریک انجام شد. نتایج نشان داد که درصد جوانه زنی تا پتانسیل 0/75- مگاپاسکال تفاوت معنی داری با شاهد (آب مقطر) نداشته و پس از آن کاهش نشان داد. سرعت جوانه زنی تا پتانسیل 0/5- مگاپاسکال تغییر معنی داری نکرد ولی پس از آن کاهش یافت. متوسط زمان جوانه زنی تا پتانسیل 0/5- مگاپاسکال تفاوت معنی داری با شاهد نداشت و با منفی­ تر شدن پتانسیل آب افزایش نشان داد. با افزایش شدت تنش خشکی شاخص بنیه گیاهچه، وزن خشک گیاهچه و طول ریشه ­چه و ساقه­ چه به طور معنی داری کاهش یافتند. در شاخص نسبت طول ریشه­ چه به ساقه چه تا پتانسیل 1/25- مگاپاسکال تفاوت معنی داری در بین تیمارها مشاهده نشد و پس از آن کاهش یافت. از نتایج فوق مشخص می­شودکه جوانه زنی گیاه خرفه تا حد زیادی به تنش خشکی مقاوم می­باشد و می­توان استقرار این گیاه را با مدیریت مناسب در خاک های مناطق خشک و با محدودیت آبی تضمین نمود.

The studying effect of drought stress on germination, proline, sugar, lipid, protein and chlorophyll content in purslane ( Portulaca oleracea L.) leaves

Abstract: Purslane (Portulaca oleracea L.) is one of the valuable medical plants. Drought also is one of the most important environment stresses that influences metabolism and growth of plant. The studying of physiological plant response rather than water stress can be influential equipment for understanding drought resistance mechanisms. In this study, the drought stress effects on germination and physiological characteristic of the medical plant (purslane) were studied. Drought imposed on polyethylene glycol (PEG) seedlings and experiments were done in completely random model framework, with 3 replications. Polyethylene glycol stress was in seven levels involving blank (distilled water), -0.1, -0.2, -0.4, -0.6, -0.8 and -1 MPa. In relation to germination, meaningful difference was not observed between blank and the different levels (P<0.01); and the least rate of germination in stress level was -0.4 MPa) and the highest rate of germination in stress level was -0.2 MPa). Meaningful increase of proline and sugar synchronized with PEG concentration was observed in statistical level (P<0.01) with meaningful difference. In this, blank had the least rates and stress level of -1 MPa and the highest proline and sugar rates. Lipid content in purslane leaves with increasing stress level was decreased. In the highest lipid rate in stress level (-0.2 MPa) and the least concentration in stress level (-1 MPa), it was observed that this difference in P<0.01 was meaningful. The concentration of leave proteins with meaningful decrease (P<0.01) had the highest protein concentrations in blank and the least concentration in stress level was -1 MPa. In stress effect on leaf chlorophyll content, meaningful increase of chlorophyll a and b synchronized imposed increase of stress level. It was observed that with chlorophyll a the highest concentration in stress level was -0.6 MPa and the least concentration exists in blank; and also with chlorophyll b the stress level, -1 MPa had the highest and blank had the least concentration (P<0.01). Key words: Purslane (Portulaca oleracea L.), drought, polyethylene glycol, proline, sugar, lipid, protein, chlorophyll, germination.

The genus Portulaca as a suitable model to study the mechanisms of plant tolerance to drought and salinity

Abstract: Abstract Drought and soil salinity are at present the major factors responsible for the global reduction of crop yields, and the problem will become more severe in the coming decades because of climate change effects. The most promising strategy to achieve the increased agricultural production that will be required to meet food demands worldwide will be based on the enhancement of crop stress tolerance, by both, traditional breeding and genetic engineering. This, in turn, requires a deep understanding of the mechanisms of tolerance which, although based on a conserved set of basic responses, vary widely among plant species. Therefore, the use of different plant models to investigate these mechanisms appears to be a sensible approach. The genus Portulaca could be a suitable model to carry out these studies, as some of its taxa have been described as tolerant to drought and/or salinity. Information on relevant mechanisms of tolerance to salt and water stress can be obtained by correlating the activation of specific defence pathways with the relative stress resistance of the investigated species. Also, species of the genus could be economically attractive as ‘new’ crops for ‘saline’ and ‘arid’, sustainable agriculture, as medicinal plants, highly nutritious vegetable crops and ornamentals.

Effects of Nanosilicon Dioxide Application on in Vitro Proliferation of Apple Rootstock

Abstract: Although silicon (Si) is the second most abundant element of the earth's crust and in soils, it is not listed among the essential elements for plants. However, the beneficial role of Si in stimulating the growth and development of many plant species has been recognized. This study investigated the effects of in vitro application of nanosilicon oxide on growth and proliferation of apple rootstock MM106 in tissue culture. The experiment included five levels nanosilicon oxide (0, 25, 50, 100, and 200 mg/L) added to Murashige and Skoog medium. The results showed that using nanosilicon increased in fresh and dry weights, length and number of branches, and chlorophyll in explants with the highest increase being at 100 mg/L. Growth suppression occurred at 200 mg/L. This investigation showed that 100 mg/L silicon oxide can be added to Murashige and Skoog medium for fast growth and proliferation of MM106 apple rootstock explants.

Association mapping and candidate genes for physiological non-destructive traits: Chlorophyll content, canopy temperature, and specific leaf area under normal and saline conditions in wheat

Abstract: Wheat plants experience substantial physiological adaptation when exposed to salt stress. Identifying such physiological mechanisms and their genetic control is especially important to improve its salt tolerance. In this study, leaf chlorophyll content (CC), leaf canopy temperature (CT), and specific leaf area (SLA) were scored in a set of 153 (103 having the best genotypic data were used for GWAS analysis) highly diverse wheat genotypes under control and salt stress. On average, CC and SLA decreased under salt stress, while the CT average was higher under salt stress compared to the control. CT was negatively and significantly correlated with CC under both conditions, while no correlation was found between SLA and CC and CT together. High genetic variation and broad-sense-heritability estimates were found among genotypes for all traits. The genome wide association study revealed important QTLs for CC under both conditions (10) and SLA under salt stress (four). These QTLs were located on chromosomes 1B, 2B, 2D, 3A, 3B, 5A, 5B, and 7B. All QTLs detected in this study had major effects with R2 extending from 20.20% to 30.90%. The analysis of gene annotation revealed three important candidate genes (TraesCS5A02G355900, TraesCS1B02G479100, and TraesCS2D02G509500). These genes are found to be involved in the response to salt stress in wheat with high expression levels under salt stress compared to control based on mining in data bases.