اثر تيمارهاي پرايمينگ بذر بر سبز شدن زنيان تحت سطوح مختلف آبياري

The effect of seed priming treatments on emergence of Carum copticum under under different irrigation levels

ارزيابي تحمل به كم‌آبي گياهان دارويي، به‌منظور كشت در مناطق خشك و شور از اهميت ويژه‌اي برخوردار است. جوانه‌زني و استقرار گياهان دارويي به علت قوه ناميه كم با مشكل مواجه است و تنش‌هاي محيطي، به‌ويژه خشكي بيش از عوامل ديگر موجب كاهش سبز شدن اين گياهان مي‌گردند. پرايمينگ بذر ازجمله روش‌هايي است كه منجر به افزايش قابليت جوانه‌زني در شرايط تنش مي‌شود. بدين منظور براي بررسي اثر تيمارهاي مختلف پرايمينگ بذر بر بهبود پارامترهاي سبز شدن گياه زنيان، آزمايشي به‌صورت كرت خردشده در قالب طرح بلوك كامل تصادفي با 3 تكرار در مزرعه دانشگاه شهركرد اجرا شد. سطوح مختلف آبياري (آبياري پس از 11، 22 و 33 ميلي‌متر تبخير از تشتك تبخير) به‌عنوان عامل اصلي و تيمارهاي پرايمينگ بذر (عدم پرايمينگ، هيدروپرايمينگ، نيترات پتاسيم، سولفات روي، پلي‎اتيلن گليكول 6000 و جيبرليك اسيد) به‌عنوان عامل فرعي در نظر گرفته شدند. نتايج نشان داد در شرايط تنش ملايم (آبياري بعد از 22 ميلي‎متر تبخير)، بيشترين سرعت و درصد سبز شدن با پلي‎اتيلن گليكول و بيشترين وزن خشك ريشه‌ با جيبرليك اسيد، نيترات پتاسيم، پلي‎اتيلن گليكول و سولفات حاصل شد. علاوه بر اين تحت شرايط بدون تنش، طول ريشه، طول اندام هوايي، وزن خشك اندام هوايي، ضريب آلومتري نه‌تنها با پرايمينگ بذور بهبود نيافت حتي مقادير اين صفات نسبت به بذور پرايم نشده كاهش يافت. در شرايط تنش شديد (آبياري بعد از 33 ميلي‎متر تبخير), سرعت و درصد سبز شدن و شاخص ويگور با تيمارهاي پلي‎اتيلن گليكول، جيبرليك اسيد، سولفات روي افزايش يافت و بيشترين طول ريشه (6/75 سانتي‌متر) و طول اندام هوايي (4/4 سانتي‌متر) به ترتيب در تيمارهاي جيبرليك اسيد و سولفات روي مشاهده شد. همچنين پرايمينگ با سولفات روي باعث افزايش معني‌دار وزن خشك اندام هوايي (16/12 ميلي‌گرم گياهچه) و ضريب آلومتري (0/82) گرديد. به‌طوركلي مي‌توان نتيجه‎گيري نمود كه در شرايط تنش خشكي پارامترهاي سبز شدن بذور پرايم شده با سولفات روي در مقايسه با ساير تيمارهاي پرايمينگ بذر ارتقا يافت، بنابراين اين تيمار براي تعديل اثرات محدودكننده تنش خشكي بر رشد گياهچه زنيان توصيه مي‎شود.

Introduction Water scarcity is one of the main problems in the agricultural land around the world. The climate changes indicate a rise in temperature and a decrease in average rainfall, which that its augments the drought stress effects in future (Farre and Faci, 2006). Tolerance to dehydration plants to grow in arid and salty is very important. Germination and establishment of plants due to low viability is difficult and environmental stresses, especially drought than other factors are reduction of green. Priming one of the ways to increase the germination under stress conditions. The aim of this study is to investigate the effect of seed priming treatments on emergence parameters improve of ajowan (Carum copticum L.) medicinal plant.   Material and methods A split plot experiment was conducted in randomized complete block design with three replications at farm of agricultural college, Shahrekord University, 2014. Different levels of irrigation (irrigation after 11, 22, and 33 mm evaporation from pan evaporation class A) were evaluated as the main plot and seed priming treatments consisted of no priming (control), hydropriming (seed soaking in distilled water for 36 hours), KNO3 (seeds were placed on potassium nitrate 4%), ZnSO4 (seeds were placed on potassium nitrate 0.1%), PEG600 (seeds were placed on 12 bar of polyethylene glycol) and GA3 (seeds were placed on 100 ppm of gibberellic acid) as subplot. Treatments were chosen according to a preliminary priming experiment. The amount of potassium nitrate required is calculated using equation Want hoof (Siebert and Richardson, 2002). In this experiment, parameters such as rate of emergence, percentage of emergence, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index were evaluated. data were analyzed by using both one or twoway analysis of variance (ANOVA) and mean comparisons were performed by LSD test if Ftest was significant at (p < 0.05) to determine whether differences among means were significant between treatments drought stress and seed priming.   Results and discussion The results showed that emergence percentage, root dry weight, soot dry weight, vigor index were influenced by drought stress (p < 0.05, p < 0.01, and p < 0.01, respectively). The seed priming effect for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant (p < 0.01, p < 0.01, p < 0.01, p < 0.05, p < 0.01, p < 0.01, p < 0.01, p < 0.01, and p < 0.01, respectively). The drought stress × seed priming interactions for emergence rate, emergence percentage, root dry weight, shoot dry weight, root length, shoot length, shoot dry weight, allometric coefficient, and vigor index was significant were statistically significant. Means comparison results indicated that in mild stress (irrigation after 22 mm evaporation), the highest rate and percentage of emergence were obtained in PEG treatment. The greatest of root dry weight was observed in GA3, KNO3, and ZnSO4, and PEG treatments. In addition, root length, shoot length, shoot dry weight, allometric coefficient of primed seed not only not improved but also values of these characters declined in compare to nonprimed seed. In severe stress (irrigation after 33 mm evaporation), rate and percentage of emergence and vigor index increased in PEG, GA3, ZnSO4. Also, The maximum root length (6.7 cm) and shoot length (4.4 cm), were observed GA3 and ZnSO4, respectively.Primed seed with ZnSO4 increased shoot dry weight (16.12mg) and the allometric coefficient (0.82), as well as.   Conclusions In overall it can be concluded that in drought stress conditions, seed priming of ajowan medicinal plant with gibberellic acid and zinc sulfate improves germination and seedling growth in farming systems. Thus, these pretreatments increases root growth and strengthen and better establishment seedling under drought stress conditions that it would be appropriate for the development of production in such semiarid environments. In addition, by reducing the frequency of irrigation for optimum seedling establishment can make good use of water resources in these areas.