تأثیر کاربرد هیومیک‌اسید غنی‎شده با نیتروژن (‏NHA‏) بر ویژگی‎های مورفولوژیک و فیزیولوژیک ‏ذرت (سینگل کراس 704)‏

نویسندگان

1 دانشجوی دکتری، گروه علوم ومهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز

2 استاد، گروه علوم ومهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز

چکیده

هیومیک‌اسیدهای غنی‎شده با نیتروژن (‏NHA‏) به‎عنوان کود نیتروژن و محرک رشد گیاه مورد استفاده قرار گرفته‌اند. ‏در پژوهش‎‎‏ حاضر، ‏NHA‏ از واکنش نیتریک‌اسید با هیومیک‌اسید (‏HA‏) استخراج‎شده از لئوناردیت تهیه شد و درصد نیتروژن ‏آن به‌روش آنالیز ‏CHNS‏ تعیین گردید. سپس، یک آزمایش گلخانه‎ای با کشت ذرت در قالب طرح کاملاً تصادفی با 16 تیمار ‏شامل شاهد (بدون مصرف اوره،HA‏ و ‏NHA‏) و ‏اوره (‏U‏)، هیومیک‌اسید (‏HA‏)،اوره-هیومیک‌اسید (‏UHA‏)، هیومیک‌‏اسید ‏غنی‌شده با نیتروژن (‏NHA‏) و اوره-هیومیک‌اسید غنی‌شده با نیتروژن (‏UNHA‏) هر‌کدام در سه سطح و در سه تکرار انجام ‏شد. ‏سطوح تیمارها بر‌مبنای ربع (‏‎ mg N kg-1‎‏50)، نصف (‏‎ mg N kg-1‎‏100) و برابر نیاز کودی ذرت (‏‎ mg N kg-1‎‏200) ‏تعیین ‏شدند و در تیمارهای مخلوط، سهم برابری از نیتروژن برای اوره، ‏HA‏ و یا ‏NHA‏ در نظر گرفته شد. نتایج حاکی از ‏کارایی مطلقاً زیادتر ‏NHA‏ نسبت ‏HA‏ و نیز کارایی قدری زیادتر ‏UNHA‏ نسبت به اوره در ارتقای اغلب ویژگی‌های ‏مورفولوژیک ذرت بود. همچنین، به‎طور‌متوسط، شاخص کلروفیل برگ و غلظت‎های نیتروژن، نیترات و فعالیت آنزیم ‏نیترات‌ردوکتاز شاخساره در تیمارهایNHA ‎‏ به‎ترتیب 5/11، 0/17، 2/35 و 4/29 درصد بیش‌تر از تیمارهایHA ‎‏ بود. ‏با‌این‌حال، تیمارهای ‏UNHA‏ و اوره در اغلب صفات فیزیولوژیک نتایج تقریباً مشابهی را نشان دادند. بیش‌ترین غلظت ‏نیتروژن و نیترات در گیاه متعلق به ‏تیمار ‏U3‎‏ بود، اما بالاترین میزان آبشویی نیترات نیز در همین تیمار مشاهده شد که با ‏کاربرد تیمار ‏U3NHA3‎‏ حدود 7/48 ‏درصد کاهش یافت. با توجه به یافته‎ها، ‏UNHA‏ می‎تواند به‌عنوان کود نیتروژن مطرح شود ‏که نیاز به پژوهش‌های بیش‌تری دارد.‏

کلیدواژه‌ها


عنوان مقاله [English]

Effect of Application of Nitrogen-enriched Humic Acid (NHA) on Morphological ‎and Physiological Characteristics of Maize (Single cross 704) ‎

نویسندگان [English]

  • Mansour Mirzaei Varoei 1
  • shahin oustan 2
  • Adel Reyhanitabar 2
  • Nosratollah Najafi 2
1 Ph.D. candidate, Soil Science Dept., Faculty of Agriculture, University of Tabriz
2 Prof., Soil Science Dept., Faculty of Agriculture, University of Tabriz
چکیده [English]

Background and Objectives
Nitrogen (N) plays a major role in maize growth and yield. Therefore, adequate supply of N is required ‎for successful maize production. However, application of chemical nitrogen fertilizers is associated with ‎some problems such as groundwater ‎pollution, nitrogen enrichment of surface waters, and nitrate ‎accumulation in agricultural products. ‎Accordingly, nowadays a great attention has been paid to the ‎slow-release fertilizers. Nitrogen-enriched humic acids ‎‎(NHAs) are considered as promising slow-release ‎nitrogen fertilizers in agricultural systems. However, the ‎effects of these types of fertilizers on plant growth ‎and physiological characteristics have not been well ‎understood. For this purpose, the present study ‎investigates the effectiveness of NHAs on the ‎morphological and physiological characteristics of maize as ‎well as nitrogen loss through leaching. ‎
Methodology ‎
The Nitrogen-enriched humic acids (NHAs) were prepared through the simple process of nitration, and ‎from the reaction of nitric acid with humic acid (HA) ‎extracted from leonardite of Yazd Golsang Kavir ‎Company as an organic carbon source. Then, a ‎greenhouse experiment in a completely randomized ‎design (CRD) with three replications was conducted ‎to determine the effects of 16 treatments, including ‎control, urea (U1, U2 and U3), humic acid ‎‎(HA1, HA2 and HA3), nitrogen-enriched humic acid (NHA1, ‎NHA2 and NHA3), urea-humic acid (U1HA1, U2HA2 ‎and U3HA3), and urea-nitrogen-enriched humic acid ‎‎(U1NHA1, U2NHA2 and U3NHA3) on the morphological ‎and physiological characteristics of maize plant ‎‎(Single cross-704). The levels of treatments were ‎determined as the quarter (50 mg N kg-1), half (100 mg ‎N kg-1) and equal (200 mg N kg-1) to the maize ‎fertilizer requirement. In the combined treatments of urea ‎and HA or NHA, an equal fraction of the total ‎nitrogen was considered. After the end of the experiment, ‎using the standard methods, some ‎characteristics including root length, leaf area, plant height, root ‎volume, wet and dry weights of shoot ‎and root, leaf chlorophyll index, concentrations of phosphorus, ‎potassium, nitrogen and nitrate, and ‎nitrate reductase activity in both shoot and root were determined. ‎Moreover, during the experiment and ‎on given days, the maize pots were leached and the obtained ‎leachate was collected for the nitrate ‎measurement. ‎
Findings
According to the results, the nitrogen content of the produced NHA (3.3%) was about two times‏ ‏higher ‎than the HA (1.6%). In addition, the NHA had higher‎‏ ‏carboxyl and phenolic hydroxyl content than the ‎HA. The FT-IR analysis showed the characteristic peaks of nitro (NO2) groups at wavenumbers of 1541 ‎and 1336 cm-1 in the spectrum of NHA. Germination test indicated that the NHA was not toxic to the maize ‎seeds. The results showed that the NHA treatments had a much better influence on the plant ‎morphological characteristics than ‎the ‏HA treatments. This observation may be due to the negative effects ‎of HA application at high dosages. In comparision, the UNHA treatments were only slightly more efficient ‎than the urea treatments. Combining‏ ‏NHA with urea diminishes the adverse impacts of separate ‎application of these two fertilizers. On average, leaf chlorophyll index and concentrations of total ‎nitrogen, nitrate and nitrate reductase enzyme in shoot part of plants in the NHA treatments were 11.5, ‎‎17.0, 35.2 and 29.4% higher than the HA tratments. The nitrate reductase concentration in the roots was ‎‎40.4% lower than the shoots. However, the UNHA and urea treatments showed almost similar efficiency ‎in improving physiological characteristics. The U3NHA3 or U3 treatments, i.e. the highest level of ‎nitrogen, showed the highest efficiency which means the high nitrogen requirements of maize in pot ‎experiments. Based on the results, the nitrogen supply to the maize plant increased the shoot ‎concentration of potassium higher than that of phosphorus. Although the U3 treatment indicated ‎the ‎highest nitrogen and nitrate concentrations in both root and shoot, the highest nitrate leaching was ‎also ‎observed for this treatment. However, by using the U3NHA3 treatment, the mean concentration of ‎nitrate ‎in the leachate decreased by about 48.7% as compared to the U3 treatment. ‎
Conclusion ‎
Findings of this research revealed that the combined fertilizer of UNHA can be ‎a good alternative for ‎urea. It could not only supply nitrogen for plants, but could improve plant vegetative ‎growth, and in turn ‎considerably reduce nitrate leaching, which has highly beneficial effects on nitrogen use ‎efficiency as well ‎as environmental issues.‎

کلیدواژه‌ها [English]

  • Leonardite
  • Nitric acid
  • Nitrate leaching
  • Nitrate reductase enzyme
  • Urea‎
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