Detection of Cadmium Risk to the Photosynthetic Performance of Hybrid Pennisetum

Abstract

Photosynthesis plays an essential role in plant growth and crop yield, and the mechanisms of the effects of cadmium (Cd) on photosynthetic performance require more attention. The acute toxicity of Cd in soil to the photosynthetic capacity of Hybrid Pennisetum was evaluated using gas exchange parameters, A / C i curves, light response curves, and chlorophyll a fluorescence transients after exposure to elevated Cd concentrations (0, 10, 20, 50, 70, and 100 mg kg −1 ) for a 3-month period. The results indicated that leaf Cd concentration in Hybrid Pennisetum increased with the strength of soil Cd stress and ranged from 4.9 to 15.8 μg g −1 DW. The accumulation of leaf Cd severely restricted photosynthesis and its non-stomatal limitation in regulating the photosynthetic performance of Hybrid Pennisetum . The leaf chloroplasts at 10 and 20 mg kg −1 Cd concentrations showed no noticeable change, but the chlorophyll content significantly decreased by 9.0–20.4% at 50–100 mg kg −1 Cd concentrations. The Cd treatments also decreased plant ribulose-1,5-bisphosphate (RuBP) activity ( V cmax ) and regeneration capacity ( J max ), triose phosphate utilization ( TPU ), light-saturated photosynthesis ( A max ), apparent quantum yield ( AQY ), light saturation point ( LSP ), and dark respiration ( R day ), but Cd treatment increased the light compensation point ( LCP ). The shape of chlorophyll a fluorescence transients in leaves was altered under different Cd treatments. The increased OJ phase and the decreased IP phase in fluorescence induction curves suggested that Cd toxicity inhibited both light use efficiency and photodamage avoidance ability. These results suggested that the decrease in photosynthesis through exposure to Cd may be a result of the decrease in leaf chlorophyll content, Rubisco activity, and RuBP regeneration, inhibition of triose phosphate utilization, reduction of the ability to use light and provide energy, and restrictions on electron transport in PSII.

Ameliorative Effects of Exogenous Proline on Photosynthetic Attributes, Nutrients Uptake, and Oxidative Stresses under Cadmium in Pigeon Pea (Cajanus cajan L.)

“…In our current experiment, photosynthetic attributes and pigments were reduced in pigeon pea under different cadmium treatments (Table 2). Our results are consistent with previous findings, where similar reduced photosynthetic attributes have been observed in other plant species [24,55,56,59].…”

“…Cadmium reduces stomatal density, decreases stomatal pore size, and affects its normal opening and closing mechanism [21,55,56]. Cadmium ions disturb the thylakoid membrane chain and thus decrease rubisco efficiency in carbon fixation [24,55].…”

“…Cadmium ions disturb the thylakoid membrane chain and thus decrease rubisco efficiency in carbon fixation [24,55]. Moreover, the production of elevated H 2 O 2 contents in the leaves in Cd stress environments may also affect photosynthetic chain performance [55,56]. Chlorophylls play a vital role in the light reaction of photosynthesis.…”

Determination of the Best Controlled-Release Potassium Chloride and Fulvic Acid Rates for an Optimum Cotton Yield and Soil Available Potassium

“…The fluorescence parameters of chlorophyll, including the primary light energy conversion efficiency ( F v / F m ), non-photochemical quenching coefficient ( q N ), photochemical quenching coefficient ( q P ), and effective quantum yield of PSII photochemistry ( Φ PSII), were measured by an FMS2 portable fluorescence system (Hansatech instruments, King’s Lynn, Norfolk, United Kingdom). The F v / F m determination required leaves to be dark-adapted for half an hour ( Song et al, 2019 ).…”

Combined Effects of Inoculating Serendipita Indica on Soybean Growth and Soil Health Under Cd Stress

“…The main reason for this result may be that the host selected was different (Klichowska et al 2019). There was research also indicated that the decrease of photosynthesis under Cd stress was related to the decrease of carboxylase and ribose 1, 5diphosphate carboxylase activities (Song et al 2019). However, the application of S. indica enhanced Gs, Pn, Tr of soybean (Table 2).…”