Evaluation of vermicompost and foliar methanol application on antioxidant activity of leaf, compatible osmolytes and some traits of triticale under salinity stress

Introduction Salinity is a global challenge issue that is drastically reducing agricultural production. More than 800 million hectares of agricultural land suffer from soil salinity. Intense salinity stress may cause accelerated aging enzymatic and metabolic disorders of the plant. Salinity stress leads to plant death by reducing photosynthetic carbon dioxide uptake and electron transport activity, chlorophyll degradation, reactive oxygen species (ROS) accumulation, and membrane damage. Methanol is one of the simplest alcohols, which is oxidized in the form of formaldehyde and carbon dioxide in the plant, and is produced in the form of amino acids (serine and methionine) and carbohydrates in various tissues of three-carbon plants (C3). Plants treated with methanol can increase their net absorption rate. Vermicompost provides a great potential to enhance crop productivity besides protecting soil health and environmental sustainability. Its application also enhances the physico-chemical, as well as the organic properties of the soil. Vermicompost is a solid product of organic residues enriched with earthworms and other micro-faunas that provide a significant source of growth regulator hormones, degrading enzymes (such as chitinase, cellulase, lipase, amylase, and proteases), and some essential vitamins. The aim of this study was the investigation the effects of vermicompost and methanol on the activity of antioxidant enzymes, compatible osmolytes and some traits of triticale under saline conditions. Materials and methods An experiment was conducted as factorial based on randomized complete block design with three replications in greenhouse research of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2022. Experimental factors were included salinity in three levels (no salinity as control, salinity 50 and 100 mM by NaCl), application of vermicompost at two levels (without vermicompost as control and application of vermicompost) and methanol foliar application in three levels (foliar application with water as control, foliar application 15 and 30% volume). "Sanabad" cultivar was used. The seeds were placed in a cold incubator (model IKH.RI90) for 12 days at 2°C for vernalization. The amount of vermicompost used in this experiment was 6 tons per hectare (equivalent to 83.08 g.pot-1). In this study, activity of CAT, PPO, POD, soluble sugar, protein, proline, MDA, H2O2, EC, RWC and grain yield were investigated. Electrical conductivity (EC) values were measured using an electrical-conductivity meter (Mi 180 Bench Meter model). The activity of antioxidant enzymes (CAT, PPO and POD) by the method of Sudhakar (Sudhakar et al., 2001), the total protein content of the flag leaf by the Bradford method (Bradford, 1976), the content of soluble sugars by method of Dubios (Dubios et al., 1956), malondialdehyde content by Stewart and Beweley's method (Stewart and Beweley, 1980), proline content by Bates et al.'s method (Bates et al., 1973) and hydrogen peroxide content was measured by the method of Alexieva et al. (Alexieva et al., 2001) on the flag leaf at the flowering stage (61 BBCH). At plant maturity, five plants of each pot were randomly harvested to measure grain yield per plant. Analysis of variance and mean comparisons were performed using SAS9.4 computer software packages. The main effects and interactions were tested using the least significant difference (LSD) test at 0.05 probability level. Results and discussion The results showed that both application of vermicompost and foliar application of 30% volume of methanol under salinity 100 mM increased the activity of peroxidase (73.4%), polyphenol oxidase (89.6%), soluble sugar (20.3%), protein (38%), proline (101.9%) and relative water content (20.6%) in compared to no application of vermicompost and methanol under the same of salinity level. Application of vermicompost decreased MDA and H2O2 content (9 and 20% respectively) in compared to no application of vermicompost. Foliar application of 30% volume of methanol decreased MDA and H2O2 content (40 and 55% respectively) in compared to no methanol application. Maximum of grain yield was obtained in both application of vermicompost and methanol at 30% volume under no salinity. Conclusion Based on the results of this study, it seems that the application of vermicompost and methanol can increase the grain yield of triticale under salinity stress due to improving activity of antioxidant enzymes and compatible osmolytes.