| Jute?Corchorus capsularis L.?is the most commonly used natural fiber as reinforcement in green composites and,due to its huge biomass,deep rooting system,and metal tolerance in stressed environments,it is an excellent candidate for the phytoremediation of different heavy metals.Furthermore,Corchorus species are indigenous leafy vegetables and show phytoremediation potential for different heavy metals.This species has been used for the phytoremediation of different toxic pollutants such as Cu,Ni,Zn,Cd,Pb,and many others which can cause toxicity in plants.The accumulation of these toxic heavy metals in agricultural regions initiates concerns regarding food safety and reductions in plant productivity and crop yield.There is a need to remediate soils contaminated with toxic substances,and phytoremediation is a cheap,effective,and in situ alternative,and jute can be used for this purpose.Thus,the cultivation of jute?Corchorus capsularis L.?plant cv.C-3,Hong Tie Gu Xuan and Gu Ba Chang Jia using various levels of Cu and phosphorus P has been established to get higher biomass and Cu concentration in an artificially spiked and naturally aged Cu contaminated soils.In the present studies,the effect of phytotoxicity of Cu and fertilization of P were evaluated on plant growth,biomass,photosynthetic pigments,gaseous exchange attributes,fibre yield and quality,oxidative stress,antioxidative response and TEM analysis in the green house experiment.The results from these studies could offer basis for the cultivation of C.capsularis as a fibrous crop using optimal levels of P fertilizer for higher biomass and phytoremediation potential in Cu mining soils of China.The main results were summarized as follows:1. Effect of different levels of Cu on morphology and physiology of C.capsularis plantThis experiment was carried out to examine the growth,antioxidant capacity,gaseous exchange attributes,and phytoremediation potential of C.capsularis grown at different concentrations of Cu(0,100,200,300,and 400 mg kg-1)in a glass house environment.The results illustrate that C.capsularis can tolerate Cu concentrations of up to 300 mg kg-1without significant decreases in growth or biomass,but further increases in Cu concentration(i.e.,400 mg kg-1)lead to significant reductions in plant growth and biomass.The photosynthetic pigments and gaseous exchange attributes in the leaves of C.capsularis decreased as the Cu concentration in the soil increased.Furthermore,high concentrations of Cu in the soil caused lipid peroxidation by increasing the malondialdehyde content in the leaves.This implies that elevated Cu levels cause oxidative damage in C.capsularis.Antioxidants,such as superoxidase dismutase and peroxidase,come into play to scavenge the reactive oxygen species which are generated as a result of oxidative stress.In the present study,the concentrations of Cu in different parts of the plant?the roots,leaves,stem core,and fibres?were also investigated at four different stages of the life cycle of C.capsularis,i.e.,30,60,90,and 120 days after sowing?DAS?.The results of this investigation reveal that,in the earlier stages of the growth,Cu was highly accumulated in the belowground parts of the plant while little was transported to the aboveground parts.Contrastingly,at a fully mature stage of the growth?120 DAS?,it was observed that the majority of Cu was transported to the aboveground parts of the plant and very little accumulated in the belowground parts.The results also show a progressive increase in Cu uptake in response to increasing Cu concentrations in the soil,suggesting that C.capsularis is a potential bio-resource for the phytoremediation of Cu in Cu-contaminated soil.2. Influence of phosphorus on copper phytoextraction in two jute?Corchorus capsularis L.?varieties grown in a copper mining soilSoil in mining areas is typically highly contaminated with heavy metals and lack essential nutrients for plants.P reduces oxidative stress,improves plant growth,composition,and cellular structure,as well as facilitates the phytoremediation potential of fibrous crop plant species.In this study,we investigated two jute?Corchorus capsularis?varieties Hong Tie Gu Xuan and Gu Ba Chang Jia cultivated in Cu-contaminated soil(2221mg kg-1),under different applications of phosphorus(0,30,60,and 120 kg ha-1)at both anatomical and physiological levels.At the same Cu concentration,the tolerance index of Hong Tie Gu Xuan was higher than that of Gu Ba Chang Jia,indicating that Hong Tie Gu Xuan may be more tolerant to Cu stress.Although the normal concentration of P(60 kg ha-1)in the soil improved plant growth,biomass,chlorophyll content,fibre yield and quality,and gaseous exchange attributes.However,high concentration of P(120 kg ha-1)was toxic to both jute varieties affected morphological and physiological attributes of the plants under same level of Cu.Moreover,Cu toxicity increased the oxidative stress in the leaves of both jute varieties was overcome by the activities of antioxidant enzymes.Furthermore,the high concentration of Cu altered the ultrastructure of chloroplasts,plastoglobuli,mitochondria,and many other cellular organelles in both jute varieties.Thus,phytoextraction of Cu by both jute varieties increased with the increase in P application in the Cu-contaminated soil.This suggests that P application enhanced the phytoremediation potential jute plants and can be cultivated as fibrous crop in Cu-contaminated sites. |
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