پديد آورندگان :
كمالي، مريم دانشگاه فردوسي مشهد - دانشكده كشاورزي - گروه علوم باغباني , شور، محمود دانشگاه فردوسي مشهد - دانشكده كشاورزي - گروه علوم باغباني , نعمتي، حسين دانشگاه فردوسي مشهد - دانشكده كشاورزي - گروه علوم باغباني , لكزيان، امير دانشگاه فردوسي مشهد - دانشكده كشاورزي - گروه خاكشناسي , خزاعي، حميدرضا دانشگاه فردوسي مشهد - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات
كليدواژه :
نشت الكتروليت , كلروفيل كل , سطح ويژه برگ , تعداد گل , پرولين
چكيده فارسي :
كمبود آب از تنش هاي مهم غيرزيستي است كه رشد گياه را به شدت تحت تاثير قرار مي دهد. به منظور بررسي اثر تنش آبي بر سه رقم گل اطلسي پركاربرد در فضاي سبز شهر مشهد آزمايشي گلداني به صورت فاكتوريل بر پايه طرح كاملا تصادفي در چهار تكرار طراحي و اجرا شد. تيمارهاي آزمايشي شامل 4 سطح آبياري (100 درصد (شاهد))، 80، 60 و 40 درصد ظرفيت زراعي) و 3 رقم اطلسي (Supercascade، Tango blue و Tango white) بود. نتايج نشان داد برهمكنش اثر رقم و سطوح آبياري بر وزن خشك، سطح برگ، تعدادگل، قطر گل، طول جام گل، كلروفيل كل، نشت الكتروليت، محتواي رطوبت نسبي و ميزان پرولين معني دار بود. بيشترين وزن خشك ساقه (76/1گرم) در شاهد تنش (100 درصد ظرفيت زراعي) و در رقم Tango White بود. ضمن اينكه بيشترين وزن خشك برگ (07/2 گرم) و وزن خشك ريشه (43/0 گرم) در رقم Tango Blue مشاهده شد. با افزايش تنش از 100 درصد به 40 درصد ظرفيت زراعي، سطح برگ در رقم Supercascade از 314 به 49، در رقم Tango Blue از 405 به 44 و در رقم Tango White از 459 به 69 سانتي متر مربع رسيد. بعد از اعمال تنش 80 درصد در رقم Supercascade2 درصد، در رقم Tango Blue10 درصد و در رقم Tango White 3 درصد و بعد از اعمال تنش 40 درصد در رقم Supercascade17 درصد، در رقم Tango Blue9 درصد و در رقم Tango White10 درصد نشت الكتروليت نسبت به شاهد افزايش يافت. مقايسه ميانگين اثرات متقابل تنش خشكي و رقم بر مقدار پرولين نيز نشان داد بيشترين مقدار پرولين در رقم Tango White و در تنش خشكي 40 درصد ظرفيت زراعي و پس از آن در رقم Tango Blue و در تنش 40 درصد تجمع يافته است. به طور كلي دو رقم Tango Blue و Tango White هم در شرايط شاهد آبياري رشد بهتري داشتند و هم در شرايط كم آبياري مقاوم تر بودند.
چكيده لاتين :
Introduction
Water deficiency is one of important abiotic stresses that severely effects on plant growth. The effects of drought range from morphological to molecular levels and are evident at all phenological stages of plant growth at whatever stage the water deficit takes place. Growth is accomplished through cell division, cell enlargement and differentiation, and involves genetic, physiological, ecological and morphological events and their complex interactions. The quality and quantity of plant growth depend on these events, which are affected by water deficit. Cell growth is one of the most drought-sensitive physiological processes due to the reduction in turgor pressure. Under severe water deficiency, cell elongation of higher plants can be inhibited by interruption of water flow from the xylem to the surrounding elongating cells. Impaired mitosis, cell elongation and expansion result in reduced plant height, leaf area and crop growth under drought. Chlorophyll content is one of the major factors affecting photosynthetic capacity changing in chlorophyll content of plant under drought stress has been observed in different plant species and its intensity depends on stress rate and duration. Chlorophyll content of leaf is indicator of photosynthetic capability of plant tissues. In the mid-80s, RWC was introduced as a best criterion for plant water status which, afterwards was used instead of plant water potential as RWC referring to its relation with cell volume, accurately can indicate the balance between absorbed water by plant and consumed through transpiration.
Materials and Methods
To study the effects of drought stress on three varieties of petunia, a factorial experiment based on randomized complete block design with four replications was conducted. The treatments consisted of four irrigation levels ((100% control), 80%, 60% and 40% of field capacity) and three varieties of petunia (Supercascade, Tango blue and Tango white). After planting and transplanting and after full deployment in the pot, water stress treatments were applied on three varieties of petunias. At the end of each week fully blossomed flowers were counted, flower diameter, peduncle length and corolla length were measured. In order to determine the stability of the cell membrane electrolyte leakage index was measured. Specific leaf area (SLA) was determined. The amount of chlorophyll a, b, total and carotenoid and relative water content in the leaves were measured. Statistical analysis was performed using the software MSTAT-C. EXCEL was used for diagramming software. Means were compared using LSD test with a 0.05 significance level.
Results and Discussion
Results indicated that interaction impacts of variety and irrigation on dry weight, leaf area, flower number, flower diameter, length Corolla, chlorophyll content, electrolyte leakage, relative water content and proline content was significant. The most shoot dry weight (76/1 g) was in control stress (100% FC) and Tango White variety. Also the most leaf dry weight (07/2 g) and root dry weight (g 43/0) were in Tango Blue variety. With increasing drought stress from 100% FC to 40% FC, leaf area decreased in Supercascade from 314 to 49, in Tango Blue from 405 to 44 and in Tango White from 459 to 69 cm2. In 80% FC, electrolyte leakage increased in all varieties (Supercascade variety 2%, Tango Blue 10% and in Tango White 3%) compared to control. Also electrolyte leakage increased in Supercascade 17%, in Tango Blue 9% and in Tango White10% in 40% FC compared to control. Comparison of interaction effects of drought stress and variety also showed the most proline had accumulated in Tango White and drought 40% of field capacity and then in Tango Blue and stress 40% of field capacity. Generally two varieties of Tango Blue and Tango White in control irrigation had better growth and also in low irrigation were more resistant.
