Effects of Modifiers on the Growth, Photosynthesis, and Antioxidant Enzymes of Cotton Under Cadmium Toxicity

et al. 2020

Sci Rep

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Consistent use of large amounts of fertilizers, pesticides, and mulch can cause the accumulation of harmful substances in cotton plants. Among these harmful substances, cadmium (Cd), an undegradable element, stands out as being particularly highly toxic to plants. The objective of this study was to evaluate the ability of biochar (3%) and biofertilizer (1.5%) to decrease Cd uptake, increase cotton dry weight, and modulate the activities of photosynthetic and peroxidase (POD), superoxide dismutase (SOD), catalase enzyme (CAT) in cotton (Gossypium hirsutum L.) grown in Cd-contaminated soil (0, 1, 2, or 4 mg Cd kg−1 soil) in pots. These studies showed that, as expected, exogenous Cd adversely affects cotton chlorophyll and photosynthesis. However, biochar and biofertilizer increased cotton dry weight by an average of 16.82% and 32.62%, respectively. Meanwhile, biochar and biofertilizer decreased the accumulation of Cd in cotton organs, and there was a significant reduction in the amount of Cd in bolls (P < 0.05). Biochar and biofertilizer have a positive impact on cotton chlorophyll content, net photosynthesis, stomatal conductance, transpiration rate, and intercellular CO2 concentration. Thus, the addition of biochar and biofertilizer promote cotton growth. However, biochar and biofertilizer increased the SOD activity of leaves (47.70% and 77.21%), CAT activity of leaves (35.40% and 72.82%), SOD activity of roots (33.62% and 39.37%), and CAT activity of roots (36.91% and 60.29%), respectively, and the addition of biochar and biofertilizer decreased the content of MDA and electrolyte leakage rate. Redundancy analyses showed that biochar and biofertilizer also improved SOD and POD activities by reducing the heavy metal-induced oxidative stress in cotton and reducing Cd uptake in cotton organs. Therefore, biochar and biofertilizer have a positive effect on the growth of cotton.

Section: Introductionmentioning

confidence: 99%

Effects of biochar and biofertilizer on cadmium-contaminated cotton growth and the antioxidative defense system

Zhu

et al. 2020

Sci Rep

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“…For stem-girdling cottons, the content of K + and Na + in leaf were increased, and the content of Na + in root was decreased; moreover, the regulation effect of stem girdling on ion homeostasis in leaf and root was more prominent under saline stress, indicating that the regulation mechanism of ion homeostasis by stem girdling are different under saline stress and alkaline stress (Ma et al, 2020). Although stem girdling reduced the K + and Na + transport efficiency, the application of OPCM maintained the ion homeostasis in organs (An et al, 2019). Through RDA analysis, it was found that the effect of OPCM on the activities of SOD and POD in leaf and REC, Na + , and soluble sugar contents in root of cottons with stem girdling were consistent with that on those of cottons without stem girdling.…”

Section: Discussionmentioning

confidence: 96%

“…Preparation of enzyme extract: Potassium phosphate buffer (5 ml, 50 mM, pH: 7.8) was added to 0.5 g sample of each organ and ground to homogenate after an ice bath (An et al, 2019). The homogenate was centrifuged at 10,000 r min −1 for 20 min at 4°C, and the enzyme activity was measured spectrophotometrically using the supernatant.…”

Section: Measurement Of Enzymes Of Antioxidant Systemmentioning

confidence: 99%

Effects of Organic Polymer Compound Material on K+ and Na+ Distribution and Physiological Characteristics of Cotton Under Saline and Alkaline Stresses

et al. 2021

Front. Plant Sci.

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Soil salinization and alkalization greatly restrict crop growth and yield. In this study, NaCl (8 g kg−1) and Na2CO3 (8 g kg−1) were used to create saline stress and alkaline stress on cotton in pot cultivation in the field, and organic polymer compound material (OPCM) and stem girdling were applied before cotton sowing and at flowering and boll-forming stage, respectively, aiming to determine the effects of OPCM on K+ and Na+ absorption and transport and physiological characteristics of cotton leaf and root. The results showed that after applying the OPCM, the Na+ content in leaf of cotton under saline stress and alkaline stress were decreased by 7.72 and 6.49%, respectively, the K+/Na+ ratio in leaf were increased by 5.65 and 19.10%, respectively, the Na+ content in root were decreased by 9.57 and 0.53%, respectively, the K+/Na+ ratio in root were increased by 65.77 and 55.84%, respectively, and the transport coefficients of K+ and Na+ from leaf to root were increased by 39.59 and 21.38%, respectively. The activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and the relative electrical conductivity (REC) in cotton leaf were significantly increased, while the content of malondialdehyde (MDA) was decreased; but the changes in those in root were not significant. The boll weights were increased by 11.40 and 13.37%, respectively, compared with those for the control. After stem girdling, the application of OPCM still promoted the ion transport of cotton organs; moreover, the CAT activity in root was increased by 25.09% under saline stress, and the SOD activity in leaf and CAT in root were increased by 42.22 and 6.91%, respectively under alkaline stress. Therefore, OPCM can significantly change the transport of K+ and Na+ to maintain the K+ and Na+ homeostasis in leaf and root, and regulate physiological and biochemical indicators to alleviate the stress-induced damage. Besides, the regulation effect of OPCM on saline stress was better than that on alkaline stress.

“…On April 5th, 2017, to maintain the original soil profile, soils were packed into plastic barrels (length × width × height = 30 cm × 30 cm × 80 cm), and then barrels were buried back into the field. Based on previous studies 14 and pre-test results, cadmium chloride (CdCl 2 •2.5H 2 O) solution was added into the barrels and mixed fully with the plough layer. The Cd content in the plough layer reached approximately 40 mg kg −1 after three weeks.…”

Section: Discussionmentioning

confidence: 99%

Study on the effects of polymer modifiers and phloem girdling on cotton in cadmium-contaminated soil in Xinjiang Province, China

Wei

et al. 2020

Sci Rep

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The effects of two liquid modifiers (polyacrylate compound modifier and organic polymer compound modifier) and phloem girdling (stem girdling and branch girdling) on cadmium (Cd) content, Cd transport, and photosynthetic parameters of cotton (Xinluzao 60) in Cd-contaminated soil (40 mg kg −1) were studied through barrel experiment. The results showed that the distribution ratios of Cd in stem, leaves, and bolls, leaf net photosynthetic rate (Pn), leaf stomatal conductance (Gs), leaf transpiration rate (Tr), and chlorophyll content were decreased after girdling; and the application of modifiers reduced the Cd content and the Cd transported to the shoot, while alleviating photosynthetic damage caused by girdling. In general, our results indicated that the inhibition of carbohydrate supply caused by girdling reduced the photosynthetic capacity of cotton, while the applications of the two liquid modifiers decrease the influence to cotton photosynthesis. Moreover, Cd and modifiers may be transported to the shoot through both phloem and xylem. Cadmium (Cd) is a toxic heavy metal commonly found in agricultural soils 1. It is not necessary for plants, but it is easily absorbed by plant root and enriched in different tissues and organs 2. Therefore, many scholars have studied the accumulation of Cd in crops and tried to reduce the uptake of Cd by crops. For example, Sebastian et al. 3 found that the application of organic acids reduced the accumulation of Cd in plant leaves, while the application of malic acid reduced the accumulation of Cd in plant roots. Shi et al. 4 found that super absorbent polymer (SAP) immobilized heavy metals in soil, which had a positive effect on maize photosynthesis and growth. Moreover, to reduce the accumulation of Cd, it is necessary to understand the mechanism of Cd transport in plants 5,6. Mori et al. 7 indicated that the xylem unloading limited the transport of Cd from root to shoots of wild eggplant. Qin et al. 8 found that phloem played a leading role in the transport of Cd from root to leaves. However, there is no conclusive study on the transport of Cd in cotton at present. Photosynthesis is a biological process in which plants convert light energy into chemical energy that can be used in life processes and synthesize organic matter. It is the physiological basis of plant survival and one of the most basic physiological processes in plant production 9. However, Cd may inhibit photosynthesis of plants 10. Moradi and Ehsanzadeh 11 reported that Cd inhibited chlorophyll synthesis, resulting in a decrease in the amount of light-harvesting chlorophyll a/b-binding protein. Paunov et al. 12 reported that Cd interfered with the photosynthetic electron-transfer process and decreased the efficiency of energy conversion in photosystem II. Therefore, the remediation of Cd pollution has been studied through plant photosynthesis regulation. For example, Liu et al. 13 found that the application of salicylic acid significantly reduced Cd absorption in most Cd-stressed plants and restored photosynthet...