تاثیر لیگاندهای آلی بر رشد و ترکیب شیمیایی ذرت و آزادسازی عناصر در یک خاک تیمارشده با خاکستر لاستیک

یکی از مهم‌ترین عوامل محدودکننده رشد و عملکرد گیاهان کمبود روی است. با توجه به اهمیت بازیافت لاستیک‌های فرسوده و امکان استفاده از آن‌ها در کشاورزی، پژوهش حاضر با هدف بررسی اثر کاربرد خاکستر لاستیک و لیگاندهای آلی بر فراهمی عنصر روی در خاک و جذب آن توسط گیاه ذرت انجام شد. این پژوهش به‎صورت فاکتوریل با دو عامل خاکستر لاستیک در چهار سطح (0، 0/25، 0/5 و 1 درصد وزنی) و لیگاندهای آلی (شاهد، اسید سیتریک و edta با غلظت 1/5 میلی‌مول بر کیلوگرم خاک) در قالب طرح کاملاً تصادفی با سه تکرار در شرایط گلخانه انجام شد. نتایج نشان داد کاربرد لیگاندهای آلی در خاک‌های تیمارشده با خاکستر لاستیک، نتوانست بر صفات رویشی گیاه ذرت تاثیر‌گذار باشد این در حالی است که غلظت روی شاخساره و ریشه گیاه با کاربرد لیگاندهای آلی در گلدان‌‌های تیمارشده با خاکستر لاستیک افزایش یافت. با کاربرد اسید سیتریک در تیمارهای دارای 1 درصد وزنی خاکستر لاستیک افزایش سه برابری در غلظت روی شاخساره در مقایسه با شاهد (بدون‌ تیمار) مشاهده شد. هم‌چنین مقدار روی قابل عصاره‌گیری با dtpa در خاک با کاربرد سطوح 0/5 و 1 درصد وزنی خاکستر لاستیک به‌ترتیب 95 و 175 برابر نسبت به سطح صفر خاکستر افزایش یافت. همچنین نتایج نشان داد که به‌دلیل مقادیر اندک سرب و کادمیوم در لاستیک، غلظت کادمیوم شاخساره و ریشه گیاه در همه تیمارها کم‌تر از حد تشخیص دستگاه جذب اتمی بود و از طرف دیگر اثر اصلی تیمار خاکستر لاستیک، لیگاند و همچنین اثر برهمکنش آن‌ها بر غلظت سرب گیاه معنی‌داری نبود. یافته های این پژوهش نشان داد که ذرات لاستیک تایر توانست در کوتاه‌مدت روی مورد نیاز گیاه را تامین کنند. البته ضروری است آثار تولید خاکستر لاستیک بر سلامت انسان و محیط زیست بررسی شود.

effect of organic ligands on the growth and chemical composition of corn and the release of elements in a soil treated with rubber ash

abstractone of the most important factors limiting the growth and yield of plants is the zinc deficiency. considering the importance of recycling rubber tires and the possibility of using them in agriculture, the present study aims to investigate the effect of organic ligands on the availability of zn in rubber ash-treated soils. the present research was carried out in factorial form in a completely randomized design with three replications under greenhouse conditions. the treatments included four levels of rubber ash (0, 0.25, 0.5 and 1 %w/w) and three levels of organic ligands (control, citric acid and edta with a concentration of 1.5 mmol kg-1 soil). the results showed that the application of organic ligands in soils treated with rubber ash could not affect the vegetative traits of corn plants, while the concentration of zn in the aerial organs and plant roots increased with the application of organic ligands in pots treated with rubber ash. the highest concentration of zn was observed at the level of 1 %w/w rubber ash and with the use of edta ligand. in addition, the concentration of zn extractable by dtpa in the soil increased significantly with the use of rubber ash treatment. the results also showed that the treatment of rubber ash, ligand and their interactive effects did not affect the concentration of cd and pb in plants. the results of this research showed that the tire rubber particles could provide zinc required by the plant in a short period of time. of course, it is necessary to study the effects of gases produced during rubber ash production on human health and the environment.background and objective: zinc deficiency has become a warning factor in many agricultural soils around the world, including iran. in order to maximize the productivity of plants, it is imperative to ameliorate the issue of zn deficiency (nasirzadeh et al., 2023). todays, in addition to chemical fertilizers, the use of soil amendments such as municipal waste ash, animal and plant fertilizers, and biodegradable polymers has been considered. tire rubber is rich in zn and may be used as an effective and safe fertilizer source for supplying this nutrient with no risk of heavy metals contamination (moghaddasi et al., 2015). it is reported that ground tire rubber and rubber ash are efficient amendments for increasing bioavailable zn in calcareous soils (nasirzadeh et al., 2023). the aim of the present study was to investigate the effect of tire rubber ash and organic ligands application on the bioavailability of zn in a calcareous soil and uptake of this element by corn.methods: the experiment was performed as factorial in a completely randomized design with three replications. factors included tire rubber ash at four levels (0, 0.25, 0.5 and 1 %w/w) and organic ligand at three levels (control, citric acid and edta at concentrations of 1.5 mmol kg-1). before planting, soil samples (0–30 cm) from an agricultural field were collected, air-dried, and crushed to pass a 2-mm sieve. samples of tire rubber debris were obtained from the rubber industry of barez tire in iran. rubber ash was produced by ashing ground tire rubber in a furnace at 550 °c for 12 h. rubber ash was added to the pots at four levels (0, 0.25, 0.5 and 1 %w/w). the germinated corn seeds were planted in each pot, and each pot was irrigated with distilled water. after 7 weeks, seedlings were cut at the soil surface and the roots were washed free of soil. the concentrations of zn, fe, pb and cd in the shoot and root of corn plant and in the soil were measured by an atomic absorption spectrometry. growth traits measured in this experiment include stem diameter and height, leaf area, shoot and root dry weights, and fluorescence chlorophyll.results: the results showed that the zn concentration in the tire rubber ash samples was about 5%. the application of rubber ash did not significantly affect the growth traits (stem diameter and height, leaf area, shoot and root dry weights, and fluorescence chlorophyll). with increasing rubber ash levels, shoot and root zn concentrations increased by 4- and 10-folds as compared to control, respectively. furthermore, the application of edta ligand to the rubber ash treated-soil resulted in 8- and 72-fold increases in the shoot and root zn concentrations as compared to the control, respectively. additionally, adding rubber ash alone to soil and co-applying edta ligand and rubber ash increased bioavailable concentration of zn by 132- and 161-folds, respectively, as compared to the control. at the highest level of rubber ash (i.e., 1 %w/w), with the application of edta ligand, the concentration of dtpa-extractable fe in the soil increased by 33% compared to the treatment without ligand. the concentrations of pb and cd in the shoots and roots in all treatments was below the detection limit of atomic absorption spectrometry. besides, single addition of rubber ash to soil and co-application of edta ligand and rubber ash increased the bioavailable concentration of zn by 132- and 161-folds as compared to the control, respectively.conclusions: results of this study showed that the use of rubber ash can increase the bioavailability of soil zn and meet the plants need for zinc. of course, it is necessary to study the effects of gases produced during rubber ash production on human health and the environment.references:1. moghaddasi, s., khoshgoftarmanesh, a.h., karimzadeh, f., chaney, r., 2015. fate and effect of tire rubber ash nano-particles (ranps) in cucumber. ecotoxicol. environ. saf. 115, 137–143.2. nasirzadeh, a., hamidpour, m., abbaszadeh-dahaji, p., akhgar, a., kariman, k., 2023. zinc-solubilizing pseudomonas strains improve zinc nutrition of maize plants grown in sand amended with tire waste powder. j. plant nutr. 46(14), 3450–3468, https://doi.org/10.1080/01904167.2023.2206424.