圆叶锦葵对Cd处理的光合生理响应及Cd富集特征

为揭示镉(Cd)处理下圆叶锦葵的光合耐性及其对Cd的富集特征,通过土壤盆栽试验,设置不同浓度Cd0(CK)、5、15、30、60、100 mg·kg^-1]对圆叶锦葵进行处理,测定不同Cd浓度处理下圆叶锦葵的生长、光合参数、光合色素含量、抗氧化酶(SOD、CAT、POD、APX)活性及对Cd的富集能力。结果表明,Cd处理促进了圆叶锦葵的生长,30 mg·kg^-1 Cd处理下生物量达到最大值。Cd处理下,光合速率(Pn)、蒸腾速率(Tr)均呈先增加后降低的趋势,5~60 mg·kg^-1处理时Pn和Tr显著高于CK,100 mg·kg^-1Cd处理下的Pn和Tr显著低于CK。Cd处理下,叶绿素a含量增加,而叶绿素b、总叶绿素含量和类胡萝卜素含量呈先升高后降低的趋势,分别在5 mg·kg^-1和30 mg·kg^-1处理时达到最大值,Cd处理下的光合色素含量均显著高于CK。0~5 mg·kg^-1Cd处理下的光合作用受气孔因素和非气孔因素(叶面积、光合色素和抗氧化酶等)的影响;而5~100 mg·kg^-1处理下的光合作用主要受气孔因素的影响。随着 Cd 浓度的增加,圆叶锦葵根、茎、叶组织中 Cd 含量逐渐增加,其生物富集系数(BCF)和转运系数(TF)均大于1.0,BCF值在5 mg·kg^-1Cd处理时达到最大值,其对Cd具有较强的富集能力,TF值在100 mg·kg^-1Cd处理时显著升高,且达到最大值(7.37),其对Cd具有较强的转运能力;100 mg·kg^-1Cd处理下,圆叶锦葵根、茎、叶组织中Cd>100 mg·kg^-1DW。综上,圆叶锦葵对Cd具有较强的光合耐性和超富集能力,是一种潜在的超富集植物。本研究结果为挖掘新的植物修复材料提供了理论依据。

Changes in Photosynthesis and Cd Accumulation Characteristic of Malva pusilla Smith Under Different Concentrations of Cd

In this study, in order to reveal the photosynthetic tolerance and accumulation characteristics of Malva pusilla Smith, a pot experiment was conducted to observe and analyse the growth parameters, photosynthetic gas exchange parameters, photosynthetic pigment content, antioxidant enzyme (SOD, CAT, POD, APX) activity of Malva pusilla Smith and enrichment characteristics of Cd in different concentrations of Cd 0(CK), 5, 15, 30, 60, 100 mg·kg^-1]. The research results showed that 5-100 mg·kg^-1 treatments promoted the growth of Malva pusilla Smith, and its biomass reached the maximum when the Cd concentration was 30 mg·kg^-1. With Cd concentrations increasing, the tendency of the photosynthetic rate (Pn) and transpiration rate (Tr) increased first and then decreased, Pn and Tr were significantly higher than controls when the treatment was 5-60 mg·kg^-1, but Pn and Tr was significantly lower than control when the treatment was 100 mg·kg^-1. The content of chlorophyll a increased under cadmium treatment, while chlorophyll b, total chlorophyll and carotenoid content increased first and then decreased, reaching the maximum at 5 mg·kg^-1 and 30 mg·kg^-1, respectively. The content of photosynthetic pigments under Cd treatment was significantly higher than that of CK. Stomatal factors and non-stomatal factors including leafy area, photosynthetic pigment and antioxidant enzymes affected the photosynthesis when the treatment was 5-60 mg·kg^-1, and stomatal factors affected the photosynthesis when the treatment was 100 mg·kg^-1. With the increasing concentration of Cd, the bioconcentration factor (BCF) and transfer factor (TF) were both greater than 1.0, and the BCF values reached a maximum with 5 mg·kg^-1 treatment indicating the plant had a strong ability to accumulate Cd. The TF value increased significantly at 100 mg·kg^-1 and reached a maximum of 7.37, indicating the plant had a strong transport capacity. The concentration of cadmium in the tissues exceeded 100 mg·kg^-1 when the treatment of Cd arriving 100 mg·kg^-1. The results showed that the Malva pusilla Smith had strong ability of photosynthetic tolerance and hyperaccumulation under cadmium treatment, indicating Malva pusilla Smith was a potentially hyperaccumulator. This study provided a theoretical basis for identifying new phytoremediation materials.