ارزيابي و گزينش ژنوتيپ هاي جو (Hordeum vulgare L.) دابل هاپلوئيد بر اساس صفات ريشه‌اي در مرحله گياهچه اي تحت شرايط نرمال و تنش شوري

Evaluation and selection of barley (Hordeum vulgare L.) doubled haploid genotypes based on root traits in seedling stage under normal and salt stress conditions

درك نحوه رشد و توسعه اندام هاي مختلف گياه، به‌ويژه ريشه، در مديريت بهينه توليد گياهان شورزيست از اهميت زيادي برخوردار است. اين پژوهش به منظور بررسي اثر شوري كلريد سديم بر روي صفات ريشه گياهچه هاي جو دابل هاپلوئيد با دو سطح شوري صفر (شاهد) و 150 ميلي مولار انجام گرفت. آزمايش به‌صورت فاكتوريل در قالب طرح كاملاً تصادفي با سه تكرار در پاييز 1391 در دانشكده كشاورزي دانشگاه زنجان انجام شد. صفاتي از قبيل سطح ريشه، زاويه ريشه، طول تجمعي ريشه، طول بلندترين ريشه و قطر ريشه اندازه‌گيري شدند. نتايج نشان داد كه بين لاين ها و اثر متقابل لاين × شوري اختلاف معني داري در سطح احتمال يك درصد وجود دارد. به طوركلي شوري باعث كاهش معني دار سطح ريشه، طول تجمعي و طول بلندترين ريشه شد. در چهار لاين طول بلندترين ريشه تحت تنش شوري كاهش نيافت. در مورد طول تجمعي ريشه نيز سه لاين تحت تنش شوري روند كاهشي نشان ندادند. در تمام لاين ها به‌غيراز شش لاين، زاويه ريشه در شرايط فاقد تنش بيشتر از زاويه ريشه در شرايط تنش بود. مساحت ريشه نيز در شرايط تنش داراي روند نزولي نسبت به شرايط نرمال بود كه پنج لاين از اين قانون تبعيت نكردند. روند تأثير تنش شوري در بين لاين ها بر روي صفت قطر ريشه يكسان نبود. با استفاده از تجزيه كلاستر،  لاين هاي دابل هاپلوئيد جو بر اساس صفات موردمطالعه در هر دو محيط نرمال و تنش شوري به دو گروه تقسيم شدند و ژنوتيپ هاي شماره 2، 29 و 62 به عنوان ژنوتيپ هاي برتر در هر دو شرايط گزينش گرديدند.

Salinity is a major abiotic stress affecting agricultural production. Barley is one of the most tolerant species among glycophyte plants to salt stress. High tolerance of barley to salinity stress is related to its rapid phonological growth and development. Understanding of growth and development of different organs of plant, especially root, is important for optimal management of halophytes (Chen et al., 2008). Root systems can exhibit enormous plasticity on the level of biomass, morphology, and or physiology in response to different environmental parameters such as water and nutrient availability. Because root system traits, such as water uptake rates per surface area, are defined by the properties of individual root segments detailed studies about the abundance, morphology, anatomy, and physiology of individual roots are needed (Rewald et al., 2012). Root length can be the most important characteristics because many researchers believe that the root length per unit volume of soil is the best feature to calculate water uptake by the plant (White and Kirkegaard, 2010). The root diameter reduces in salt stress conditions. It varies in different species (Eshel and Beeckman, 2013). Grouping of accessions by multivariate methods in would be of practical value to wheat breeders in that representative accessions may be chosen from different clusters for breeding purpose and it also helps to define strategies for further collection of germ plasm (Alavi siney et al., 2013). The objectives of this study were to evaluate effect of NaCl salinity on seedling root traits in doubled haploid barley, grouping, ranking and selecting of superior genotypes based on studied traits.  Materials and methods: In order to investigate the effect of NaCl salinity on seedling root traits in doubled haploid barley, a study was carried out as a factorial experiment based on completely randomized design with three replications in the green house of Zanjan University in 2012. Fifty doubled haploid lines were studied in zero (control) and 150 mM salinity levels. Traits of the root area, root angle, cumulative root length, length of the longest root, diameter root were measured with daily imaging of the seedling. Data were analyzed by the analysis of variance (ANOVA) with using SPSS (21). Cluster analysis and Aronachalam and Bandyopadhyay(1984) were used for grouping and ranking the doubled haploid lines respectively. Results and Discussion The results of the variance analysis showed significant differences between lines and interaction of line × salinity for all of traits. The significant differences among lines for the studied traits refer to the presence of considerable variation among lines and give a chance to plant breeders for betterment of these characters through breeding. The significant interaction between lines and Salinity shows a lines specific adaptation to different salinity. Therefore, this diversity can successfully be used for improvement of barley yield. However, the correct selection of doubled haploid lines can be considered as one of the crucial factors in farm management and economic barley production. Generally, salinity was decreased root length and cumulative root length. In four lines did not decrease the root length under salt stress and in three lines didn’t show reduced cumulative root length under salt stress. The root angle, in all lines except the six lines, under Stressfree conditions was greater than the stress condition. Root area showed a downtrend in stress conditions than under normal condition those five lines are not obeyed of the law. The effect of salinity on root diameter did not show similar results among the lines. Using cluster analysis and Arunachalam and Bandyopadhyay (1984) method, barley doubled haploid lines were divided two groups based on studied traits both normal and salinity conditions. Genotypes with 2, 29 and 69 code were selected as superior genotypes in both of conditions. Conclusion The results of experiment showed that the root traits are affected by salt stress.  Since, it is necessary, we know about the relationship between root traits such as, area and length of root and their relationship with salt stress. Salt stress decreased amount of root area, cumulative length, length of longest root and root angle. Tolerance to salinity is related to all of traits involved in salt tolerance. The root absorbs water and nutrients to the extensive role that it can play a major role in salinity tolerance. Cluster analysis based on the studied traits in both conditions (normal and stress) divided genotypes in two groups and multivariate analysis of variance confirmed these results. Arunachalam and Bandyopadhyay showed genotypes number 2, 29 and 62 were superior genotypes in both conditions. Therefore, these genotypes  can be used in both of condition.