AUTHOR=Farhangi-Abriz Salar , Ghassemi-Golezani Kazem 

TITLE=The modified biochars influence nutrient and osmotic statuses and hormonal signaling of mint plants under fluoride and cadmium toxicities

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1064409

DOI=10.3389/fpls.2022.1064409

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Chemically modified biochars are a new generation of biochars that have a great ability to absorb and stabilize environmental pollutants. In this research, the physiological performance of mint plants (<italic>Mentha crispa</italic> L.) under fluoride and cadmium toxicities and biochar treatments was evaluated.</p></sec><sec><title>Methods</title><p>Four levels of soil toxicities including non-toxic, 600 mg NaF kg<sup>-1</sup> soil, 60 mg Cd kg<sup>-1</sup> soil, and 600 mg NaF kg<sup>-1</sup> soil + 60 mg Cd kg<sup>-1</sup> soil were applied. The biochar addition to the soil was 25 g kg<sup>-1</sup> (non-biochar, solid biochar, H<sub>2</sub>O<sub>2</sub>, KOH, and H<sub>3</sub>PO<sub>4</sub>-modified biochars).</p></sec><sec><title>Results</title><p>The results showed that the application of biochar and especially chemically modified biochars reduced fluoride (about 15-37%) and cadmium (30-52%) contents in mint leaves, while increased soil pH and cation exchange capacity (CEC), nitrogen (12-35%), phosphorus (16-59%), potassium (17-52%), calcium (19-47%), magnesium (28-77%), iron (37-114%), zinc (45-226%), photosynthetic pigments of leaves and plant biomass (about 10-25%) under toxic conditions.</p></sec><sec><title>Discussion</title><p>The biochar-related treatments reduced the osmotic stress and osmolytes content (proline, soluble proteins, and carbohydrates) in plant leaves. Plant leaf water content was increased by solid and modified biochar, up to 8% in toxic conditions. Furthermore, these treatments reduced the production of stress hormones [abscisic acid (27-55%), salicylic acid (31-50%), and jasmonic acid (6-12%)], but increased indole-3-acetic acid (14-31%) in plants under fluoride and cadmium stresses. Chemically modified biochars reduced fluoride and cadmium contents of plant leaves by about 20% and 22%, respectively, compared to solid biochar.</p></sec><sec><title>Conclusion</title><p>This result clearly shows the superiority of modified biochars in protecting plants from soil pollutants.</p></sec>