Xorazm ma ’ mun akademiyasi axborotnomasi – /2020 Ўзбекистон республикаси фанлар

 
Fig. 1. A conceptual framework for exposure of plants to heavy metals as affected by environmental factors and 
human activities. 
①
 Entry of heavy metals to the lands via using HMs-containing wastewater, pesticides, or 
fertilizers 
②
 foliar uptake of heavy metals by plants through atmospheric deposition, herbicides, dust storm, or 
volcanic emission 
③
 release of heavy metals into the soil via solubilization of minerals or mineralization of 
organic matter as mediated by plant beneficial rhizospheric microorganisms (PBRMs) 
④
 uptake of available 
heavy metals by plant roots 
⑤
 adsorption of heavy metals onto soil minerals, organic matter and biochar, 
decreasing their bioavailability 
⑥
 leaching of heavy metals from the soil profile and pollution of ground water 
⑦
 natural/synthetic chelating agents (such as EDTA) binding up to heavy metals, improving their 
bioavailability 
⑧
 enhancing the bioavailability and plant uptake of heavy metals by fungal hyphae 
⑨
 addition 
of heavy metals to the atmosphere through anthropogenic activities such as factories and smelting industries [3]. 
Materials and methods 
Sample Preparation.
Topsoil (0
–
30 cm) was collected from different Pb-Zn contaminated dark 
brown soils located in Angren Thermal Power Plant, Tashkent region (lat. 41.004897; 
lon.70.122799). Soil samples were stored in clean Ziploc plastic bags and transferred to the 
laboratory immediately. Basic physicochemical properties of the soils were determined and are 
presented in Table 1. Ryegrass seeds were sown in the pots after sterilization with 30% sodium 
hypochlorite solution for 2 min, washed three times with tap water, and rinsed with deionized water 
(DIW). 

---