نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زراعت، دانشکده کشاورزی، دانشگاه ایلام. ایران
2 گروه آب، دانشکده کشاورزی، دانشگاه ایلام. ایران
3 سازمان جهاد کشاورزی ایلام. ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
To investigate the effect of conservation tillage on soil biological and enzymatic activities and physiological characteristics of maize under drought stress conditions, an experiment was conducted based on a split-plot design in a randomized complete block design with three replications and 15 treatments in 2023 at the Ilam University Research Farm. The main therapies included three tillage levels (no-tillage, minimum tillage, and conventional tillage), and the sub-treatments included five irrigation regimes (100, 75, and 50 percent of field capacity with full irrigation and 75 and 50 percent with PRD local root drought method). The results showed that the highest relative leaf water content (85.62%) was observed in the 100 percent field capacity irrigation treatment. The highest proline accumulation (2.06 μmol/g leaf fresh weight) was observed in the 50 percent irrigation level. Catalase activity reached its maximum value (1.93 absorption change/min/mg protein) in the no-tillage treatment with 50 percent PRD irrigation. Malondialdehyde and ascorbate peroxidase also showed the highest levels at the 50% irrigation. In the section on soil enzymatic activities, alkaline phosphatase was recorded at 430.11 and 417.74 μg/g soil in the tillage treatments with 100 and 75% PRD irrigation, respectively. Acid phosphatase, urease, and microbial respiration also had the highest levels in the tillage treatment with full irrigation. The findings indicate that the combination of tillage system with the PRD technique can be used as an effective solution for drought stress management. These methods enhance plant defense responses and provide more favorable biological conditions for soil.
کلیدواژهها [English]
EXTENDED ABSTRACT
Drought is one of the primary abiotic stresses that has detrimental effects on plants. Furthermore, water scarcity has become a significant challenge in global agricultural production. One way to address this challenge is through optimal water management, which can include methods such as deficit irrigation. Partial Root-zone Drying (PRD) is an advanced deficit irrigation technique where half of the root zone is irrigated at each irrigation event. One of the initial responses of plants to water deficit stress is the production of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), superoxide (O₂⁻), and hydroxyl radicals (OH⁻). In plant cells, in response to stresses, the activity of enzymatic and non-enzymatic antioxidants increases. Enzymatic antioxidants include catalase, peroxidase, and ascorbate peroxidase. Conservation tillage systems play a significant role in arid and semi-arid regions by increasing agricultural production and maximizing surface water infiltration. Additionally, soil enzymes (acid and alkaline phosphatases, urease) produced by microbes play a key role in biochemical functions, organic matter decomposition, and nutrient cycling.
This experiment was conducted during the 2023 growing season (1402 in the Iranian calendar) at the research farm of the University of Ilam. The experiment was carried out as a split-plot design within the framework of a randomized complete block design with three replications. The main plots consisted of three tillage levels (no-tillage, minimum tillage, and conventional tillage), and the sub-plots consisted of five irrigation regimes: 100, 75, and 50 percent of soil field capacity with full irrigation, and 75 and 50 percent of soil field capacity with variable PRD. The land was plowed according to the tillage treatments. For conventional tillage, the land was plowed using a moldboard plow to a depth of 25-30 cm (without plant residue), followed by disc harrowing to break up soil clods, land leveling, and furrowing using a furrower for maize cultivation. In minimum tillage, the land was plowed using a chisel plow to a depth of 25-30 cm, leaving 50 percent of the crop residue on the soil surface. In the no-tillage treatment, the land was used for cultivation without plowing and with 100 percent plant residue cover. The size of the sub-plots was 2×2 square meters with four rows spaced 50 cm apart. The distances between blocks, main plots, and sub-plots were 2, 2, and 1 meters, respectively. Maize seeds (I-Star cultivar, FAO group 600) were manually planted on June 10, 2023 (Khordad 1402), with a spacing of 20 cm between plants and at a depth of two centimeters in the planting rows, resulting in a density of 10 plants per square meter. The field was irrigated using drip tape, and the amount of water consumed was measured by a water meter. Until the plants were fully established, all plots were irrigated uniformly, after which the application of different irrigation levels commenced. To measure the relative leaf water content, the method of Sanchez et al. (1998) was used. The method of Bates et al. (1973) was used for extraction and assay of proline. The activity of the ascorbate peroxidase enzyme was determined using the method of Ranieri et al. (2003), and the activity of the catalase enzyme was assessed using the method of Aebi (1984). Malondialdehyde content was measured using the method of Stewart & Beweley (1980). Soil microbial respiration was measured using the method of Anderson (1982), urease activity was determined using the method of Kandeler & Gerber (1988), and acid and alkaline phosphatase activities were measured using the method of Ohlinger (1996). Analysis of variance (ANOVA) of the data was performed using SAS software (ver 9.4), and the comparison of means was conducted using the Least Significant Difference (LSD) test at a 5% significance level. Excel software was used for drawing graphs.
The results showed that irrigation levels at the 1% probability level significantly affected relative water content. Based on the results of mean comparisons, the highest relative water content (85.62%) was observed at the 100% field capacity irrigation level, while the lowest relative water content was obtained at the 50% conventional and 50% PRD irrigation levels. Furthermore, the effect of different irrigation treatments on proline content was significant at the 1% probability level, with the highest proline accumulation observed at the 50% conventional irrigation level (2.06 µmol per gram fresh weight of leaf). And the highest amount of proline was obtained in the low-tillage method (1.83 micromol/g leaf fresh weight). Based on the results, the effect of irrigation was significant at the 1% probability level, and the interaction between tillage and irrigation on catalase content was significant at the 5% probability level. The highest catalase activity was observed in no-tillage with 50% PRD irrigation (1.93 changes in absorbance per minute per milligram of protein). Additionally, the effect of irrigation on malondialdehyde content was significant at the 1% probability level, with the highest activity observed at the 50% field capacity irrigation level (1.61 nmol per gram fresh weight of leaf). The effect of different irrigation treatments on ascorbate peroxidase activity was also significant at the 1% probability level, and the highest activity was obtained at the 50% conventional irrigation level (1.13 changes in absorbance per minute per milligram of protein). Based on the results, the interaction between tillage and irrigation on alkaline phosphatase, acid phosphatase, urease, and microbial respiration content was significant at the 5% probability level. Mean comparison of alkaline phosphatase enzyme activity under the interaction of tillage and irrigation levels showed that the highest alkaline phosphatase activity was in no-tillage with 100% and 75% PRD irrigation (430.11 and 417.74 µg p-nitrophenyl phosphate per gram of soil, respectively), and the highest acid phosphatase activity was in no-tillage with 100% field capacity irrigation (391.4 µg p-nitrophenyl phosphate per gram of soil). The highest urease enzyme activity was observed in no-tillage with 100% field capacity irrigation (7.89 µg nitrogen per gram of soil in two hours), and the highest microbial respiration was under no-tillage and 100% irrigation conditions (2.11 mg carbon per day).
The results indicate a significant impact of different irrigation and tillage methods on the physiological, biochemical, and biological characteristics of maize plants and soil. The findings showed that reducing the irrigation amount, particularly under drought stress conditions, led to significant changes in indicators related to relative leaf water content, proline accumulation, the activity of antioxidant enzymes such as catalase (CAT) and ascorbate peroxidase (APX), as well as lipid peroxidation (malondialdehyde, MDA). The Partial Root-zone Drying (PRD) irrigation method, compared to conventional irrigation, demonstrated greater efficiency in maintaining leaf water content and reducing oxidative stress. In the conservation tillage system, the activity of alkaline and acid phosphatase enzymes, urease, and microbial respiration was influenced by irrigation conditions and the type of tillage. The no-tillage system showed better performance in maintaining soil enzymatic activity compared to minimum tillage and conventional tillage. Furthermore, the PRD method was able to mitigate the negative effects of drought stress on soil enzymatic activity.
Nezam Karzani: Project Management, Research, Data Collection, Writing, Preparation of the Main Draft, Sources
Ehsan Zeidali: Conceptualization, Supervision, Writing - Review and Editing
Yaser Alizadeh: Conceptualization - Methodology, Software, Validation, Manuscript Editing, Supervision
Hamzeh Ali Alizadeh: Supervision - Methodology
Ekhlas Amini: Illustration, Writing - Review and Editing
Funding was provided by Ilam University.
All authors have read and approved the published version of the article.
The datasets are available upon a reasonable request to the corresponding author.
We would like to sincerely thank Ilam University for the financial and logistical support that significantly contributed during the research project.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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