The effect of irrigation water salinity on biomass and some morpho-physiological characteristics of two-year-old seedlings Vetiver grass (Chrysopogon zizanioides L)

Document Type : Research Paper

Authors

• Atefe Farjadi ¹
• Maasoumeh Movaghari ²
• Mitra Cheraghi ¹

¹ Department of Nature Reclamation Engineering, Agricultural Sciences and Natural Resources University of Khuzestan, Khuzestan, Iran

² , Department of Nature Reclamation Engineering, Agricultural Sciences and Natural Resources University of Khuzestan,, Khuzestan. Iran

Abstract

Keywords

• Khuzestan
• Range Improvement
• Halophytes

Main Subjects

• ..

Introduction

Soil salinity is a critical challenge in arid and semi-arid regions, as high evaporation and low rainfall promote salt accumulation, consequently reducing plant growth and yield. Salinity stress limits water uptake, causes ionic imbalance, and disrupts physiological functions, ultimately constraining crop productivity. Chrysopogon zizanioides (vetiver grass) is a tropical grass widely recognized for its tolerance to harsh conditions. It grows rapidly, produces deep roots reaching up to 4 m, and adapts to various soils. Reaching heights of 50–150 cm, vetiver stabilizes soil, prevents erosion, and thrives even on steep slopes. Its ability to absorb nutrients, heavy metals, and pollutants also makes it efficient for wastewater and leachate treatment. In addition to ecological functions, young leaves provide moderate nutritional value as forage in stress-prone regions. Reported salinity tolerance thresholds for vetiver vary widely, influenced by genotype, soil type, and methodology. Further studies are therefore essential to define its tolerance range and enhance applications in saline environments.

Method

This study was conducted in 2022 using two-year-old vetiver seedlings grown in 6.5 kg-capacity pots at the nursery of Khuzestan Agricultural Sciences and Natural Resources University, which is located in a dry climate. Six salinity levels (city water (as control), 4, 8, 16, 32, and 64 dS m⁻¹) were applied with four replications. To avoid osmotic shock, salinity treatments were gradually increased, and irrigation was managed using the gravimetric method with a leaching fraction to prevent excessive salt accumulation. The experiment lasted for 10 months. Growth traits, including plant height and crown diameter, were measured monthly. At the end of the experiment, fresh and dry weights of shoots (aerial parts) and roots were recorded, and total biomass was calculated. Photosynthetic pigments (chlorophylls and carotenoids), relative water content (RWC), and leaf proline concentration were also determined. To evaluate the plant’s phytoremediation potential, salt concentrations in soil, roots, and shoots were analyzed, and transfer factor (TF), bioconcentration factor (BCF), and biological accumulation coefficient (BAC) were calculated. Data were analyzed using a One-Way Analysis of Variance (ANOVA) based on a completely randomized design (CRD). Mean comparisons were then conducted using the LSD test in SPSS software.

Results

Monthly measurements of vetiver plant height showed no significant differences among salinity treatments during the initial six months. From the seventh month onward, only the 32 dS/m treatment showed a significant increase in height compared to the control. Crown diameter remained unaffected by salinity throughout the experiment. Fresh and dry weights of aerial biomass and leaves were not significantly affected; however, minor increases were observed up to 32 dS/m, followed by a decline at 64 dS/m. In contrast, root biomass was significantly reduced at higher salinity levels, particularly from 32 dS/m onward. Total biomass showed no significant changes across treatments. Photosynthetic pigments, including chlorophyll a, b, total chlorophyll, and carotenoids, were stable under all salinity levels. Leaf relative water content increased significantly only at 64 dS/m, while proline content decreased under all saline treatments. Salt accumulation analysis indicated higher salt concentrations in roots than shoots. Translocation factor (TF) values were below one, reflecting limited upward salt movement. Biological accumulation and concentration factors were also below unity, confirming effective salt regulation in plant tissues. These findings indicate that vetiver tolerates moderate to high salinity by restricting salt translocation, maintaining photosynthetic activity, and preserving leaf water content. Despite reduced root biomass under extreme salinity, the species’ adaptive responses, such as osmotic adjustment and selective ion compartmentalization, support its growth and highlight its suitability for saline soil reclamation and management.

Conclusions

The results showed that vetiver grass maintains its vegetative growth, biomass production, and photosynthetic pigments even at a high salinity level of 64 dS/m. Furthermore, it exhibits high salt tolerance by restricting salt translocation from roots to shoots. Collectively, these traits make vetiver an effective option for saline range restoration, forage production, and soil conservation.

Author Contributions

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

Data Availability Statement

The raw data generated and analyzed during this study are available from the corresponding author, Maasoumeh Movaghri, upon reasonable request and pending permission from the co-authors.

Acknowledgments
The authors gratefully acknowledge the support of Department of Nature Reclamation Engineering, Agricultural Sciences and Natural Resources University of Khuzestan, which provided facilities and guidance essential for Atefeh Farjadi’s master’s research project.

Ethical Considerations

The authors avoided data fabrication, falsification, plagiarism, and misconduct.

Conflict of Interest

The authors declare no conflict of interest.