اثر تنش‌های شوری و خشکی بر رویش جوانه‌های ریزوم گیاهarundo donax l. در شرایط دمایی مختلف

به‌منظور بررسی اثر تیمار خشکی و شوری بر مراحل رشد و زمان آغازش ریزوم گیاه قمیش arundo donax آزمایشی در سال 1399 در دانشگاه فردوسی مشهد با استفاده از ریزوم های جمع‌آوری‌شده از اکوتیپ گرگان و به‌صورت طرح کاملاً تصادفی در 4 تکرار در اتاقک رشد در 5 سطح دمایی (5، 10، 15، 20، 25 و 30 درجه سانتی‌گراد) به‌صورت جداگانه انجام شد. تیمارهای آزمایش شامل سطوح مختلف تنش خشکی {0 (آب مقطر)، 0.4-، 0.8- و 1.2- مگاپاسکال} و سطوح مختلف تنش شوری {0 (آب مقطر)، 4، 8 و 12 دسی زیمنس بر متر} بود. نتایج کلی آزمایش نشان داد که با افزایش میزان شوری و خشکی، میزان جوانه‌زنی ریزوم ها کاهش پیدا می‌کند. همچنین نتایج نشان داد که جوانه‌زنی ریزوم گیاه قمیش از دمای 5 درجه سانتی‌گراد تا دمای 30 درجه سانتی‌گراد امکان‌پذیر است اما بیشترین میزان جوانه‌زنی به میزان 74 درصد در دمای 15 درجه سانتی‌گراد اتفاق افتاد و پس ‌از آن دمای 20 درجه به مقدار 66 درصد در تیمار شاهد جوانه‌زنی داشت. کمترین درصد جوانه‌زنی در بالاترین سطح شوری و خشکی در دمای 15 و 30 درجه سانتی‌گراد به مقدار 4 درصد مشاهده شد. درصد جوانه‌زنی و سایر شاخص‌های جوانه‌زنی با کاهش دما از 15 درجه سانتی‌گراد به 5 درجه سانتی‌گراد کاهش پیدا کرد. همین روند نیز با افزایش دما از 20 درجه سانتی‌گراد به 30 درجه سانتی‌گراد مشاهده شد که نشان می‌دهد، بهترین دما برای رویش جوانه‌های ریزوم قمیش بین 15 تا 20 درجه سانتی‌گراد می‌باشد. تاثیر میزان شوری و خشکی بر میزان جوانه‌زنی در دماهای مختلف نشان داد که با افزایش سطح تنش شوری و خشکی میزان جوانه‌زنی کاهش پیدا می‌کند، اما با افزایش سطح خشکی میزان کاهش درصد جوانه‌زنی بیش از سطح شوری بود و کاهش رویش جوانه‌های ریزوم قمیش بیشتر تحت تاثیر افزایش میزان خشکی خاک قرار گرفت. اثر متقابل سه‌گانه شوری،خشکی و دما در تمامی پارامترها به‌جز سرعت جوانه‌زنی تعدیل‌شده در سطح احتمال %99 معنی‌دار بود که این امر نشان می‌دهد که جوانه‌زنی ریزوم گیاه قمیش به‌شدت تحت تیمار خشکی، شوری و دماهای مختلف قرار دارد و وجود هر یک از این تیمارها در شرایط طبیعی می‌تواند جوانه‌زنی آن را مختل نماید.

effect of salinity and drought stresses on rhizome bud sprouting of giant reed (arundo donax) under different temperature conditions

introductionthe competition of different weed species with native species for ecosystem resources is a serious threat to reduce global biodiversity. among the invasive species, arundo donax is considered one of the most invasive invasive plant species in coasts, rivers and temperate regions. knowing the relationship between changes in environmental conditions and climate change and arundo donax with respect to the growth of native coastal species, as well as understanding the water wastage by this plant compared to native coastal plants, is vital to eliminate this plant in the current situation where there is drought in most areas. materials and methodsin order to investigate the effect of drought and salinity treatment on the sprouting stages and growth time of rhizomes of arundo donax an experiment was performed using rhizomes collected from gorgan ecotype and in a completely randomized design with 4 replications in the growth chamber separately at 5 temperature levels (5, 10, 15, 20, 25 and 30 °c) at ferdowsi university of mashhad in 2020. experimental treatments included different levels of drought stress {0 (distilled water), 0.4, -0.8 and -0.12 mpa} and different levels of salinity stress {0 (distilled water), 4, 8 and 12 ds. m}.results and discussionthe general results of the experiment showed that increased levels of salinity and drought decreases the sprouting rate of rhizomes. the results also showed that sprouting of the rhizomes of the reed plant is possible from 5 °c to 30 °c, but the greatest sprouting rates occurred with the control treatment (no stress) at 15 °c (75%) and 20 ° c (66%) respectively. the lowest sprouting percentage (4%) was observed with 15 and 30 °c under the maximum salinity and drought levels. sprouting percentage and other corresponding indices decreased with decreasing temperature from 15 °c to 5 °c, the same trend was observed with increasing temperature from 20 °c to 30  c, which shows that the best the temperature for the growth of reed rhizome buds is between 15 and 20 °c. the effect of salinity and drought on sprouting at different temperatures showed that with increasing salinity and drought stress level, the sprouting rate decreases, but with increasing drought level, the sprouting percentage decreased more than the salinity level and decreased the growth of reed rhizome buds more. was affected by increasing soil dryness. the results of sprouting rate and sprouting percentage under environmental stresses also indicated that drought stress more than salinity stress can affect the growth of reed rhizome buds, in other words, this plant is more sensitive to drought stress. it is somewhat resistant to salinity stress, and perhaps this is why the abundance of this plant in the northern regions of iran is higher than other regions. the triple interaction effect of salinity, dryness and temperature was significant in all parameters except the adjusted germination rate at the 99% probability level, which shows that the germination of the rhizome of arundo donax plant is strongly affected by dryness, salinity and different temperatures and the existence of each of these treatments in natural conditions, it can disrupt its germination.conclusionthe results of the cultivation of arundo donax rhizome at different temperatures and under salt and drought stress conditions showed that the growth of the rhizome of this plant was greatly affected by the stresses and the increase in the amount of stress led to a decrease in germination percentage. also, rhizome cultivation at different temperatures led to determining the optimal germination temperature for the arundo donax plant related to the ecotype in the northern regions of iran and showed that the suitable temperature for the rhizome germination of this plant is 15 to 20 degrees celsius. the results of the germination rate and the germination percentage under the applied environmental stresses also indicated that drought stress can affect the growth of arundo donax rhizome buds more than salt stress, and in other words, this plant is more sensitive to drought stress and to some extent it is resistant to salt stress, and this is probably the reason why the abundance of this plant is more in the northern regions of iran than in other regions. it grows best in well-drained soils where plenty of moisture is available and can spread from the water’s edge to the shore far beyond the area previously occupied by woody coastal vegetation. it grows well in places where the water level is close to the soil surface or near it, which may be due to the sensitivity of this plant to drought stress, and on the other hand, small colonies of this plant can tolerate excessive salinity, but in conditions of widespread presence in one area, their tolerance to salinity decreases.