The effects of EDTA and Trichoderma species on growth and Cu uptake of maize (Zea mays) plants grown in a Cu-contaminated soil.

Metal contamination in soil poses a significant environmental concern worldwide, necessitating effective remediation strategies such as phytoremediation. The present study investigated the effects of EDTA dosage (1.5 and 3 mmol kg-1) and two Trichoderma species (T. harzianum and T. aureoviride) on copper (Cu) content and growth of maize plants grown in a Cu-contaminated soil, as well as Cu fractionation in the soil. In the absence of EDTA, only inoculation with T. harzianum led to a significant increase in shoot biomass. Combining fungal inoculum with EDTA only yielded a significant increase in shoot biomass when using T. aureoviride at a low EDTA rate, highlighting the interplay between fungal species and EDTA rates on plant growth. Results also indicated that EDTA application increased Cu bioavailability, enhancing Cu dissolution and root (not shoot) Cu concentrations. Conversely, inoculation with both Trichoderma species reduced Cu mobility and bioavailability in soil, thereby decreasing the shoot Cu concentrations of plants. When combined with EDTA, only application of T. harzianum resulted in an enhanced shoot Cu concentration, whereas combined application of T. aureoviride and EDTA did not make a significant change compared to the corresponding control (no fungal inoculation, no EDTA), possibly due to a lower compatibility of the T. aureoviride isolate with EDTA. Our results demonstrated that EDTA application, in both non-inoculated and inoculated treatments, increased Cu availability by facilitating its redistribution and transformation from less plant-available fractions (residual, Fe/Mn oxide-bound, and carbonate-bound) to the more readily plant-available forms (water-soluble and exchangeable fractions). In conclusion, although individual Trichoderma application proved beneficial for phytostabilization by reducing Cu content and mitigating Cu toxicity in plants, the combined application of EDTA and a compatible Trichoderma isolate (here, the T. harzianum isolate) holds promise for enhancing the phytoextraction capacity of plants. Although using maize has the advantage of being a food crop, to optimize phytoextraction, plant species with superior metal tolerance and phytoextraction capabilities should be selected, exceeding those of maize.

The Role of Social Support and Socioeconomic Factors in the Prediction of Depression among First-Year Undergraduate Students.

Aim: This study was devoted to determining the role of social support and socioeconomic factors in predicting students' depression. Methods: In this cross-sectional study, all first-year undergraduate students in the Shahrekord University of Medical Sciences, Iran, during the 2019-2020 academic year were included via the census method. Data collection tools include a researcher-made checklist about demographic and socioeconomic status, a standard questionnaire of perceived social support, and Beck's depression questionnaire. Smoothly clipped absolute deviation (SCAD) linear regression was used to model the role of social support and socioeconomic factors in predicting depression. Results: Out of the 220 first-year undergraduate students, 174 (79.1%) were female, and 176 (80.0%) were single. The mean ± SD of depression score among the first-year undergraduate students was 10.56 ± 5.19, and the mean ± SD of social support score was 48.86 ± 5.46. The mean score of depression was significantly higher in female students than in males (11.09 versus 8.59, P = 0.001) but was not statistically significant in different categories of age (P = 0.70), marital status (P = 0.37), ethnicity (P = 0.10), parents' education, and the other demographic variables. Pearson's correlation showed an inverse and significant correlation between depression and social support (R = -0.20, P = 0.003). The mean score of depression was at the highest level for students of public health and environmental health majors and was the lowest for students of laboratory sciences, which was statistically significant (P < 0.001). After adjusting the other variables, SCAD regression showed that social support plays a key role in depression prediction, and increasing social support leads to a decrease in depression score. Conclusion: Considering the existence of an inverse and significant correlation between depression and social support, any intervention to promote social support for first-year undergraduate students may decrease depression.