نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران، کرج. ایران
2 گروه علوم و مهندسی خاک، دانشکدگان کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران
3 گروه مهندسی محیط زیست، دانشکده محیط زیست، دانشگاه تهران، تهران، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Periphytons in aquatic ecosystems has the ability to absorb/release significant amount of nutrients. This study examines the effect of epipelon and epiphyton on changes in pH, EC and soluble potassium, periodically. This experiment was conducted as a factorial in a completely randomized design with three factors: 1- periphyton at 22 levels (9 samples of epipelon, 9 samples of epiphyton, 3 fallow soil samples and control), 2- mineral at 2 levels (muscovite and phlogopite), 3- sampling time at 4 levels (0, 7, 14 and 21). Both types of periphyton showed high potential in releasing potassium from silicate minerals. Throughout the 21-day experiment, all treatments had significant statistical differences compared to the control (without periphyton/soil but whit minerals). Overall, the highest dissolution rate from both minerals were observed in the epiphyton treatments. Potassium dissolution increased in all treatments until 7th day and then relatively decreased in most treatments by day 14, which was attributed to the increased biomass in medium. The highest soluble potassium on 21th day was 14.33 mg L-1, which showes a 3.6-fold increase compared to the control. The lowest soluble potassium levels were observed in treatments inoculated with fallow soil. Solubilization rate of phlogopite was higher than that of muscovite, but in most treatments, the difference was not statistically significant. Overall, pH and EC results showed increasing (indicating increased photosynthetic activity) and decreasing (indicating increased biomass and higher absorption of soluble materials) trends, respectively.
کلیدواژه‌ها [English]
EXTENDED ABSTRACT
Periphytic biofilms live by adhering to hard substrates in aquatic ecosystems, especially in shallow, flooded areas. They are named according to the substrate on which they are found. The primary components of periphyton formation (algae, bacteria, fungi, metazoans, protozoa) play a crucial role in nutrient cycling in aquatic ecosystems, including rice fields. These biofilms act as a high active biological buffer for continuous nutrient transformations, sedimentation and release, effectively serving as a sink/source of nutrients between the soil and the water layer. It can be used as a potential biofertilizer. Studies have shown that bacteria and fungi can release potassium by breaking down or altering the structure of potassium-bearing minerals (such as mica and feldspar). Considering that research related to the periphyton is very limited in Iran and all over the world and that such studies have only recently begun in Iran, understanding the impact and performance of periphyton is essential. On the other hand, the complex composition of the periphyton microbial community may contain elements or interactions that have not been identified yet. Therefor, examining the entire biofilm in terms of potassium dissolution, which is one of the essential elements for plant growth, is highly effective.
To conduct this research, samples were collected from three different locations in Guilan Province. Paddy field samples, including epipelon and epiphyton, as well as fallow soil samples, were taken from the soil surface in three replicates. These samples were transferred to the laboratory in an ice box and then recultured in BBM medium. A modified BBM medium with muscovite and phlogopite mica was used for quantitative analysis of potassium solubilization. In this process, 10 ml of periphyton grown in the laboratory were inoculated into 100 ml of medium containing 2.5 g L-1 of muscovite/phlogopite minerals.
The necessary greenhouse conditions for this test include: a temperature of 28 ℃, lighting at 5000 lux, a 12/12hour light/dark cycle, and daily aeration by manual shaking. This experiment, which lasted for three weeks, involved sampling at 7-day intervals to measure the EC, pH and soluble K parameters of the solution.
The amount of potassium dissolution in medium with phlogopite treatments was somewhat higher than in treatments whit muscovite. According to the potassium levels in all treatments, we observed a significant increase in soluble potassium. The potassium level in most treatments were observed on the 14th day and the highest levels being 14.33 and 14.26 mg L-1 for the periphyton number 15, indicating a 3.6-fold increase compared to the control. Next periphyton sample 17 showed a 3.5-fold increased compared to the control, whit soluble potassium of 14.21 and 14 mg L-1 both samples mentioned above belong to the Vajargah rice field. This indicates a very high rate of periphyton growth in the early days, which increased the amount of soluble potassium due to biomass growth. As periphyton grows, bacterial and fungal communities capable of dissolving potassium release this nutrient from the mineral structure. By the 14th day, we observed a decrease in soluble potassium, which may indicate the absorption of potassium into the periphyton structure.
Samples numbered 19, 20 and 21, related to fallow soil, did not have high potassium dissolution but still showed a significant difference compared to the control. But this shoed an 83% increase compared to the control.
Regarding the pH results, we observed an increase in acidity compared to the initial days of incubation, which increased simultaneously with the growth of periphyton. This may indicate an increase in photosynthetic activity. According to the EC results, all treatments caused a decrease in the EC of the medium, likely due to the increase in periphyton biomass and the resulting absorption of soluble substances by the periphyton.
The results of this research demonstrated that various types of epipelons, epiphytons and fallow soil microbiomes possess a notable ability to release potassium from silicate minerals.
Conceptualization, H.A. Alikhani. and M. Leylasi-Marand.; methodology, H.A. Alikhani.; software, M. Leylasi-Marand.; validation, H.A. Alikhani. and S. Shariati ; formal analysis, M. Leylasi-Marand.; investigation, H.A. Alikhani. and S. Shariati; resources, M. Leylasi-Marand.; data curation, M. Leylasi-Marand. S. Shariati; writing—original draft preparation, M. Leylasi-Marand.; writing—review and editing, M. Leylasi-Marand and S. Shariati.; visualization, H.A. Alikhani.; supervision, H.A. Alikhani. and S. Shariati.; project administration, H.A. Alikhani., S. Shariati and M. Leylasi-Marand.; funding acquisition, H.A. Alikhani and M. Leylasi-Marand. All authors have read and agreed to the published version of the manuscript.
Not applicable
This work is based upon research funded by Iran National Science Foundation (INSF) under project No.4000736.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The authors declare no conflict of interest.
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