The effects of mercury stress on the photosynthesis and chlorophyll fluorescence of wheat (Triticum aestivum L.) genotypes

Mercury is one of the toxic and heavy metals that causes pollution in agricultural fields. Mercury aggregation disturbs cellular behaviors and stops plant growth. In order to examine the effects of mercury on wheat growth indexes, a study with ۴ commercial genotypes of Iran, Sirvan, Sivand, Parsi and Sepahan in various levels of this element (۰, ۳۰, ۷۰, ۱۰۰ mg/kg soil) was conducted. This experiment has been conducted in a random factorial design with ۳ replications and indices including CO۲ assimilation rate (A), transpiration rate (E), stomatal conductance (gs), water use efficiency (WUE), PSII photochemical efficiency (FV/FM), photosynthesis quantum yield (Y), electron transfer rate (ETR), intra-leaf CO۲ concentration (Ci), chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/b, chlorophyll stability index and carotenoids were measured after ۶۰ days. The result indicated that all measured parameters except carotenoid were decreased as mercury concentration increased. In ۱۰۰ mg/kg stress level, Sirvan genotype had the highest transpiration rate, chlorophyll a, b, total chlorophyll, carotenoid, PSII efficiency and Ci as compared to other investigated genotypes. Also, Sepahan genotype showed the highest increase in chlorophyll stability index, stomatal conductance, ETR and quantum yield of photosynthesis at a stress level of ۱۰۰ mg/kg as compared with control plants. Parsi genotype had the lowest transpiration rate, stomatal conductance, PSII efficiency, ETR and Ci at a stress level of ۱۰۰ mg/kg as compared to other investigated genotypes. Based on these results, Parsi genotypes can be introduced as sensitive genotypes, and Sivand and Sirvan genotypes can be introduced as tolerant genotypes to mercury treatment.

Keywords:

Chlorophyll fluorescence , Mercury , Photosynthesis , Triticum aestivum , Chlorophyll fluorescence , Mercury , Photosynthesis , Triticum aestivum