Effect of Leaf Surface Regulation of Zinc Fertilizer on Absorption of Cadmium, Plumbum and Zinc in Rice (Oryza sativa L.)

Abstract

The accumulation of heavy metals in rice is bound to affect human health and safety. In order to ensure food security, this study explores the effect of leaf surface regulation of zinc (Zn) fertilizer on the safety of rice in cadmium (Cd)-plumbum (Pb) polluted farmland. Through field experiments, the leaf surface control treatment of zinc fertilizer was set up, and the effects of leaf surface control of zinc fertilizer on rice yield, Cd and Pb concentration in different parts and zinc, nitrogen, phosphorus and potassium concentration in brown rice were studied in the growing period of rice. The results showed as follows: (1) Spraying twice or more in the growth stage of rice could increase the yield by 6.77–7.29% compared with the blank, which was significantly higher than that of single spraying in a certain growth stage. (2) After spraying zinc fertilizer on the leaf surface, Cd and Pb concentration in brown rice decreased by 29.52–56.01% and 11.10–28.34%, respectively, compared with CK. Two or more times of spraying can make Cd concentration in brown rice meet the Chinese standard GB 2762-2022, and one time of spraying can make Pb concentration in brown rice meet the standard. (3) Leaf surface control of zinc fertilizer could reduce the Cd enrichment ability of rice plant parts, and the Cd enrichment coefficient of brown rice was significantly reduced by 28.18–55.02%. Leaf surface control of zinc fertilizer can reduce Cd and Pb concentration in brown rice by reducing the transport ability of heavy metal Cd and Pb in rice roots to straw and then to brown rice. (4) The zinc concentration in brown rice was 18.16–20.68 mg·kg−1, which was 18.21–34.64% higher than that in CK, and the zinc enrichment effect was the most significant after spraying three times. Meanwhile, the nitrogen, phosphorus and potassium concentration in brown rice also increased with the increase of spraying times. By comprehensive analysis, the leaf surface control of zinc fertilizer can reduce the Cd and Pb concentration in rice, and the Cd and Pb concentration in brown rice can meet the Chinese standard GB 2762-2022 by spraying twice. At the same time, it can improve the concentration of zinc, nitrogen, phosphorus and potassium in brown rice, is feasible and has high economic benefits.

Correlation and Path Analysis of Early-Maturing Rice (Oryza Sativa L.) Treated With Zinc at Various Growth Phase

“…Rice is a plant that is sensitive to Zn. The zinc fertilizer application can significantly increase Zn concentration, reduce Zn deficiency, and increase grain yield (Hu et al, 2023). The findings of Rehman et al (2012) revealed that increased grain zinc concentration is parallel with increased remobilization of zinc in leaves during the grain-filling phase.…”

“…Therefore, if there is a deficiency of Zn nutrients in plants, it can cause leaf degeneration, the appearance of macules on the leaf veins, small leaf deformation, and slow growth. However, fulfilling the zinc needs of crop plants can be better through foliar application on the leaf surface, which the leaf epidermis can absorb easily for transport to other parts of the plant through the rice xylem and phloem (Oryza sativa L.) (Hu et al, 2023).…”

Analysis of Heavy Metal Impacts on Cereal Crop Growth and Development in Contaminated Soils

“…Leaf deformities represent another distinctive manifestation of heavy metal toxicity in cereals. Certain heavy metals, such as cadmium, mercury, and nickel, can cause physical deformities in leaves, altering their normal appearance and structure [79,201]. These deformities may include curling, twisting, irregular shapes, and abnormal growth patterns.…”

“…In alkaline conditions, metals may form insoluble precipitates or bind to soil particles, making them less available for plant uptake [124]. For instance, in soils with a pH above 7, heavy metals like nickel, cadmium, and zinc are more likely to form less soluble compounds, reducing their potential toxicity to cereal crops [201,235].…”

Phytoremediation of Toxic Lead from Contaminated Soil Using Neyraudia reynaudiana: Soil of Xuzhou as a Case Study

“…In addition to using hyperaccumulator plants to rehabilitate Pb-polluted soil, it can also increase the repair effect by regulating plant growth. Leaf surface control of zinc fertilizer can reduce the Pb concentration in brown rice by reducing the transport ability of Pb in rice roots to straw and then to brown rice [11]. In the upland soils, biochars made from blends of plant and manure materials demonstrated some capacity to reduce soil Pb bioaccessibility [12].…”