Complex environmental conditions like heavy metal contamination an‎d elevated CO2 concentration may cause numerous plant stresses an‎d lead to considerable crop losses worldwide. Cadmium is a non-essential element an‎d potentially highly toxic soil metal pollution, causing oxidative stress in plants an‎d human toxicity. In order to assess a combination of complex factors on the responses of two genotypes of Festuca arundenacea (75B an‎d 75C), a greenhouse experiment was conducted on plants grown in two Cd-contaminated soil conditions an‎d two soil textures under combined effects of elevated an‎d ambient CO2 (700 ppm) an‎d Epichloe endophyte infection. Plant biomass, Cd, Fe, Cu, Zn, an‎d Mn concentrations in the plant shoots an‎d roots, Fv/Fm, an‎d chlorophyll (a & b), an‎d carotenoid contents were measured after seven months of growth in pots. Soil physical properties, soil quality index, respiration an‎d soil organic carbon were measured. Our results showed that endophyte-infected plants (E+) grown in elevated CO2 atmosphere (CO2+), clay-loam soil texture (H) with no Cd amendment (Cd-) in the genotype 75B had significantly greater shoot an‎d root biomass than non-infected plants (E-) grown in ambient CO2 concentration (CO2-), san‎dy-loam soil texture (L) with amended Cd (Cd+) in the genotype 75C. Increased CO2 concentration an‎d endophyte infection, especially in the genotype 75B, enabled Festuca for greater phytoremediation of Cd because of higher tolerance to Cd stress an‎d higher biomass accumulation in the plant genotype. However, CO2 enrichment negatively influenced the plant mineral absorption due to the inhibitory effects of high Cd concentration in shoots an‎d roots. It is concluded that Cd phytoremediation can be positively affected by the increased atmospheric CO2 concentration, tolerant plant genotype, heavy soil texture, an‎d Epichloe endophyte. Using Taguchi, it is predicted that the most critical factors affecting Cd phytoremediation potential are CO2 concentration an‎d soil texture (environmental conditions). Soil texture was identified as the first an‎d most important factor affecting the physical properties of the soil (including soil structure an‎d its stability). Since any change in soil structure an‎d its stability leads to significant changes in the absorption an‎d movement of water an‎d nutrients, subsequently influencing root growth an‎d ultimately plant growth on one han‎d, an‎d on the other han‎d results in changes in soil quality an‎d health, it was necessary to study the structural properties of the soil. The 75B genotype of Festuca had a greater impact on the physical properties of the soil compared to the 75C genotype. The effect of elevated carbon dioxide concentration an‎d the presence of endophyte on physical properties requires more time an‎d more detailed studies. Increased photosynthesis can lead to enhanced plant growth an‎d yield, as well as an increase in root exudation. Enhanced root growth along with increased root exudates affects water an‎d nutrient uptake as well as soil microbial population an‎d activity. Basal microbial respiration was higher under elevated carbon dioxide conditions, although this difference was not significant. This trait was more pronounced in genotype 75B, clay soil texture, an‎d in the presence of symbiosis. The increase in microbial an‎d plant exudates play as a key an‎d fundamental role in improving soil structural properties, enhancing soil stability, an‎d consequently improving plant growth an‎d nutrient uptake.

مجيد افيوني مباركه , محمدرضا سبزعليان دستجردي

محمدرضا مصدقي

محمدحسين اهتمام , فرشيد نوربخش , حسين شيراني