Ecotoxicological assessment of cigarette butts on morphology and photosynthetic potential of Azolla pinnata.

Cigarette butts (CBs) have become the most ubiquitous form of anthropogenic litter globally. CBs contain various hazardous chemicals that persist in the environment for longer period. These substances are susceptible to leaching into the environment through waterways. The recent study was aimed to evaluate the effects of disposed CBs on the growth and development of Azolla pinnata, an aquatic plant. It was found that after a span of 6 days, the root length, surface area, number of fronds, and photosynthetic efficacy of plant were considerably diminished on the exposure of CBs (concentrations 0 to 40). The exposure of CBs led to a decrease in the FM, FV/F0, and φP0, in contrast, the φD0 increased in response to CBs concentration. Moreover, ABS/CSm, TR0/CSm, and ET0/CSm displayed a negative correlation with CB-induced chemical stress. The performance indices were also decreased (p-value ≤ 0.05) at the highest concentration of CBs. LD50 and LD90 represent the lethal dose, obtained value for LD50 is 20.30 CBs and LD90 is 35.26 CBs through probit analysis. Our results demonstrate that the CBs cause irreversible damage of photosynthetic machinery in plants and also reflect the efficacy of chlorophyll a fluorescence analysis and JIP test for assessing the toxicity of CBs in plants.

Effects of malachite green on biochemistry and photosystem II photochemistry of Eichhornia crassipes.

Malachite green (MG) is a common synthetic dye that raises environmental concerns. This study reveals that MG has inhibitory effects on the biochemistry and physiology of Eichhornia crassipes . Effects of different concentrations of MG on ROS-scavenging enzymes, α-amylase, proline, chlorophyll pigments, and various photosynthetic parameters of E. crassipes were investigated. Chlorophyll fluorescence analysis coupled with the JIP test showed the inhibitory effects of MG on biochemistry and photosynthetic potential depended on concentration and time. Up to 2days of MG exposure, α-amylase and proline were upregulated with increasing MG concentration. When exposure time and concentration increased, all the parameters initially increased, then sharply declined. Chlorophyll content decreased with exposure time and concentration. Due to the slowing down of electron transport on the donor side brought on by MG exposure, P680+ builds up. According to an analysis of E. crassipes PSII activity, exposure to MG raises the proportion of inactive PSII reaction centres and active PSII centres. After increasing the exposure period (2, 4, and 6days) and MG concentration (50, 100, 150, and 200mgL-1 ), it decreased the absorption efficiency electron transport potential, maximal quantum yield of primary photochemistry, and the quantum yield of electron transport. These modifications led to a decline in the entire photosynthesis performance. The current research suggests that MG has detrimental effects on plants; therefore, the need for stringent regulations to prevent the release of dye-containing effluents into aquatic environments.

Effect of different waterlogging periods on biochemistry, growth, and chlorophyll a fluorescence of Arachis hypogaea L.

Peanut is among the main oil crops in India with huge economic importance. The unpredictable rainy season during the growing time of peanuts causes waterlogging in peanut fields. Waterlogging triggers major environmental limitations that negatively affect the growth, physiology, and development of peanuts. Thus, the export and production of peanuts are severely affected by waterlogging. Therefore, the understanding of metabolic mechanisms under waterlogging is important to future water-stress tolerance breeding in peanuts. This study aimed to evaluate how peanuts responded to various waterlogging conditions in terms of their development, metabolic processes, and chlorophyll fluorescence characteristics. The evaluations were carried out at different stages of peanut variety DH-86 treated with waterlogging. The peanut plants were subjected to different waterlogging periods of 20, 40, 60, 80, and 100 days. The growth parameters including total dry mass, total leaf area, and total leaves number were calculated in all treatments. The phenomenological and specific energy fluxes and maximum photosystem II efficiency (FV/Fm) were also determined. The measurements were done statistically using PCA, G-Means clustering, and correlation analysis to explore the interaction between different physiological parameters. The waterlogging for 100 days caused a significant reduction in the total number of leaves, dry mass, and total leaf area. The most sensitive parameters are specific and phenomenological energy fluxes and Fv/Fm, which notably decreased as waterlogging duration increased. The results indicated the growth and physiological performance of the peanut cv. DH-86 was affected significantly due to waterlogging and the interaction between all these parameters in waterlogging. This research focused on how peanuts respond to waterlogging stress and provides the basis for future plant breeding efforts to improve peanut waterlogging tolerance, especially in rainy regions. This will improve the sustainability of the entire peanut industry.