The effect of potassium phosphite as a defense stimulant in rice seedlings against Pyricularia oryzae and antioxidant enzymes activity

Document Type : Research Paper

Authors

• Valiollah Babaeizad ¹
• Elham Khalili ¹
• Mohammad- Ali Tajick ghanbari ²
• Vahid Khosravi ³
• Shahram Naeimi ⁴

¹ Department of Plant Protection, Faculty of crop Sciences, Sari Agricultural Sciences and Natural Resources University. Sari, Iran

² Department of Plant Protection, Faculty of crop Sciences, Sari Agricultural Sciences and Natural Resources University. Sari, Iran.

³ Department of Plant Protection Research, Rice Research Institute of Iran, Deputy of Mazandaran, Education and Extension Organization, Amol, Iran

⁴ Biological Control Research Department, National Plant Pathology Research Institute, Agricultural Research, Education and Extension Organization, Tehran, Iran.

Abstract

Keywords

• Rice blast
• Induced resistance
• Catalase
• Peroxidase
• Superoxide dismutase

Extended Abstract

Introduction

    Rice blast disease, caused by Pyricularia oryzae, threatens rice production globally and annually reduces crop yield. Chemical fungicides used to control the disease pose risks to human health and the environment. Environmentally friendly inducers can reduce reliance on chemical pesticides and mitigate associated environmental concerns. One such compound is phosphite, which has been used to manage plant diseases for decades. Potassium phosphite salt is absorbed systemically and rapidly within the plant and can induce systemic defense responses against pathogen attack through priming. In the present study, the effect of potassium phosphite (KPhi) as a defense stimulant in the control of blast disease was investigated under greenhouse conditions.

Materials and methods

   The experiment investigated the effect of potassium phosphite on disease severity in rice seedlings of the cv. Hashemi. A factorial experiment in a completely randomized design was used, with two factors:

1) Foliar treatment: potassium phosphite solution vs. sterile distilled water (control)

2) Sampling time: four levels—before inoculation (zero time) and 48, 96, and 144 hours after inoculation

Pathogen inoculation was performed two days after foliar spraying. Seedling samples were then collected for enzyme analysis. The activities of antioxidant enzymes were measured spectrophotometrically. Disease severity was assessed ten days after inoculation.

Research findings

    The results showed a significant difference in rice disease severity between treated seedlings and control, with treatment reducing disease severity. In addition, the activities of antioxidant enzymes in treated plants were higher than in control plants at all time points. Catalase activity reached its peak at 4.69 U mg⁻¹ protein 48 hours after inoculation, while the lowest activity occurred in control plants on day six. Peroxidase and superoxide dismutase (SOD) activities showed a similar increasing pattern, with peak activities for peroxidase (GPX) at 62.277 U mg⁻¹ protein and for SOD at 246.17 U mg⁻¹ protein on day six after inoculation. These increases were 1.38- and 1.30-fold, respectively, compared with control.

Conclusion

    Potassium phosphite treatment can enhance rice seedling resistance to rice blast by increasing the activity of defense-related enzymes. While these greenhouse results are promising, field trials are necessary to confirm the effectiveness of potassium phosphite for blast disease management under real-world conditions.

Author contribution

All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.

Data availability

    The data will be made available on request.

Acknowledgement

    This research was supported by the Plant Protection Department of University of Kurdistan. We thank university of Kurdistan for providing research facility and support.

Ethical consideration

The study was conducted on plant-pathogen fungus and beneficial entophy-

tic bacteria that are abundant in the environment and do not require ethical

approva

   The study was conducted on plant-pathogen fungus and beneficial entophytic fungi that are abundant in the environment and do not require ethical approval.

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.