تاثير كاربرد اسيد ساليسيليك و نيتروژن بر غلظت عناصرغذايي در گياه گندم در سطوح مختلف شوري

The effect of salicylic acid and nitrogen consumption on the concentration of nutrients in wheat at different salinity levels

شوري يكي از تنش‌هاي محيطي بسيار مهم است. در شرايط شوري، فرآهمي عناصر غذايي در محلول خاك كاهش يافته و منجر به اختلال در تغذيه و برهم خوردن تعادل عناصرغذايي گياه ميگردد. مديريت كوددهي نيتروژن به عنوان عنصر ضروري براي رشد گياهان در شرايط تنش شوري بسيار حائز اهميت است. اسيد ساليسيليك يك تنظيم كننده رشد گياهي است كه در سازوكارهاي دفاعي گياهان در مقابل تنش‌ها دخيل است. به منظور بررسي اثرات اسيد ساليسيليك و سطوح مختلف نيتروژن در شوري‌هاي مختلفِ اراضيِ شركت سهامي مزرعه نمونه واقــع در انـبار الــوم شهرستان آق قلا، استان گلستان بر غلظت عناصر غذايي گندم، آزمايشي به‌صورت اسپيلت پلات فاكتوريل در قالب طرح پايه بلوك‌هاي كامل تصادفي در 4 تكرار انجام شد. فاكتور اصلي شامل سه سطح شوري خاك، ) 4-3 زير سطح آستانه تحمل گندم (شاهد)، 11-9 و 15-13 دسي‌زيمنس بر متر) و فاكتورهاي فرعي شامل دو سطح اسيد ساليسيلك (0 و 1/5 ميلي مولار) و سه سطح كود نيتروژن (از منبع اوره 46 درصد) شامل 1) توصيه آزمون خاك، 2) 30% بيشتر از توصيه آزمون خاك و 3) 30% كمتر از توصيه آزمون خاك، بود.اسيد ساليسيليك بصورت دو بار محلول پاشي در مرحله پنجه زني به فاصله حدود 2 هفته انجام شد. تيمارهاي نيتروژني در سه مرحله -يك سوم قبل از كاشت از سولفات آمونيوم (21درصد) و دو بار سرك در مراحل پنجه‌زني و ساقهروي از اوره (46درصد)- اعمال شد. نتايج نشان داد با افزايش شوري غلظت N برگ پرچم، N و K كاه و دانه گندم كاهش يافت.

Introduction Salinity is one of the most important environmental stresses limiting agricultural production in arid and semi-arid regions, which occupies a relatively large area of arable land. Nutrient availability is decreased in saline conditions in soil solution and plant nutrient balance is changed. Nitrogen fertilizer management as an essential nutrient for plant growth is very important under salinity stress. Also, salicylic acid is a plant growth regulator involved in defense mechanisms of plants against biotic and abiotic stresses. Therefore, the aim of this study was to investigate the effect of salinity on the concentration of nutrients in wheat in response to salicylic acid consumption at different levels of nitrogen. Materials and Methods In order to investigate the effects of salicylic acid and nitrogen fertilizer application rates at different salinity levels on nutrient concentration of wheat cv. Morvarid, an experiment was conducted as a split plot factorial based on a randomized complete block design with four replications in the fields of Mazraeh-E-Nemooneh located in Anbarolum, Aq Qala city, Golestan province. The main factor included three soil salinity levels (3-4 below wheat tolerance threshold (control), 9-11 and 13-15 dS.m-1) and sub factors included two levels of salicylic acid (0 and 1.5 mM) and three levels of N fertilizer (from urea source, 46% N) were 1) N based on soil test recommendation, 2) 30% N more than soil test recommendation and 3) 30% N less than soil test recommendation, respectively. Salicylic acid was foliar applied twice for about 2 weeks in the tillering stage and 10 days after the second stage spraying, content in them was determined. Nitrogen treatments were applied in three stages - one third before planting with ammonium sulfate (21% N) and remains top-dressed with urea (46% N) at tillering and stem elongation stages. At the emergence stage of the cluster or the beginning of flowering of wheat, the amount of nitrogen in the flag leaf was measured. The concentrations of nitrogen, potassium and sodium in grain and straw were also measured by standard methods. Results and Discussion The results showed that by increasing salinity, the flag leaf N concentration, N and K concentration of wheat staw and seed decreased. However, Na concentration of straw and seeds increased. With increasing N and salicylic acid consumption, the concentration of N flag leaf, the seed and straw N and K concentrations increased, but the concentration of Na in seed and straw decreased. The interaction of salinity, salicylic acid and nitrogen on seed N and K concentrations and also on flag leaf N concentration was significant but there was no significant effect on other measured elements. Comparison of the mean of simple effects of salinity on the evaluated elements indicates a significant reduction of all studied elements due to salinity treatment. Also, comparison of the mean of simple effects of nitrogen fertilizer showed that all elements were affected by the treatment. The results of mean comparison showed a positive and significant effect of salicylic acid on the leaf N concentration of the flag leaf, so that the N concentration in the flag leaf in a 1.5 mM salicylic acid treatment was significantly increased compared to the non-use treatment. Conclusion according to the results, more nitrogen consumption at moderate salinity can have a positive effect on plant nutrition, and vice versa, at high salinity levels, it is better to reduce nitrogen consumption. The interactions of salicylic acid and nitrogen showed that in general nitrogen treatments with salicylic acid increased the N concentration of seed and straw. Nitrogen fertilization at higher and medium salinity levels increased the concentration of N and K in straw and seeds; However, at high salinity, less nitrogen fertilization improved the concentration of N and K. Also, nitrogen application with salicylic acid improved these traits under saline conditions. Therefore, the application of salicylic acid and nitrogen fertilizer management to some extent reduced the adverse effects of salinity up to moderate salinity levels and improved plant nutrition by increasing plant tolerance to salinity.Therefore, the application of salicylic acid and nitrogen fertilizer management to some extent reduced the adverse effects of salinity up to moderate salinity levels and improved plant nutrition by increasing plant tolerance to salinity.