Germination and the Biochemical Response of Pumpkin Seeds to Different Concentrations of Humic Acid under Cadmium Stress

Abstract

The poisoning of heavy metals and their accumulation in food chains are major environmental and health risks. There have been several reports that determined that pumpkins tend to collect small amounts of nitrate or heavy metals. Therefore, the aim of the present study is to investigate the effect of organic matter (humic acid) on the germination and activity of antioxidant enzymes, glycosylate cycle enzymes, and utilization of lipid and protein reserves of pumpkin seeds under cadmium stress conditions. An experiment was conducted to quantify the germination response and biochemical change of pumpkin seeds to the use of humic acid under cadmium stress conditions. The treatments were cadmium at three levels (0 (control), 100, and 200 mg.L−1) and humic acid at five levels (0 (control), 100, 200, 300, and 400 mg.L−1). Linear and sigmoidal models were used to investigate the trend of trait changes. The results show that changes in the germination percentage and seed vigor were affected by applying humic acid and cadmium stress. The highest germination percentage for pumpkins was observed without stress and cadmium stress at a concentration of 200 mg.L−1. The results of quantification for the germination and seed vigor also showed that the model of germination changes by the use of humic acid was sigmoidal in non-stress and cadmium stress conditions of 100 mg.L−1, but it was linear for seed vigor in the stress conditions of 200 mg.L−1. The activity of superoxide dismutase, catalase, peroxidase, isocitrate lyase, and malate synthase was also affected by the simultaneous use of humic acid and cadmium stress, and the trend of their changes was linear.

Embryo growth alteration and oxidative stress responses in germinating Cucurbita pepo seeds exposed to cadmium and copper toxicity

“…Our findings reveal that even at low concentrations (100 µM) of cadmium or copper, the lengths and weights of zucchini seedlings experience a significant reduction compared to the control (Table 1 ). As supported by Asadi Aghbolaghi, et al 23 , higher concentrations of cadmium (200 mg/L) can lead to the decline of protein and lipid structures due to the influence of free radicals, resulting in a reduction of these reserves. Additionally, previous studies have shown that oxidative stress induced by osmotic stress 50 and the involvement of reactive oxygen species (ROS) play a role in programmed cell death during germination and seedling development.…”

“…The phytotoxic effects of cadmium (Cd) and copper (Cu) on seed germination and seedling development have been documented by various researchers in different plant species, including zucchini ( C. pepo ) 57 , Atriplex ( A. halimus ) 59 , mung bean ( P. aureus Roxb) 60 , and rice ( O. sativa ) 61 . Recent research by Asadi Aghbolaghi, et al 23 concluded that C. pepo seeds exhibit relative tolerance to the toxic effects of cadmium at an early stage of germination, accompanied by a depletion in protein and lipid reserves, as well as a reduction in seed vigor and the activity of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POX) in germinated zucchini seeds.…”

Seed Fatty Acid Changes Germination Response to Temperature and Water Potentials in Six Sesame (Sesamum indicum L.) Cultivars: Estimating the Cardinal Temperatures

“…Variations in seed oil affect membrane lipid composition in terms of function and membrane permeability, which affects germination, establishment, and tolerance to environmental stresses [37]. In oilseeds, the first step of food storage consumption is performed by the lipase enzyme, which breaks ester bonds and releases fatty acids and glycerol due to the activity of this enzyme [38,39].…”

Influence of the application of humic substances on the growth of watermelon and melon seedlings

“…However, there is much variation in the chemical composition of humic substances, in addition to different effects depending on the crop species (Asadi Aghbolaghi et al, 2022;Rostami et al, 2022, Sensoy et al, 2022. Therefore, it is necessary to evaluate the application of humic substances in short-term cycle fruit species growing under the conditions of the Brazilian Cerrado.…”