The accumulation of Cd by rice poses significant health risks. Foliar fertilization with Zn can reduce grain Cd contents in rice grown in Cd-contaminated soils. However, atmospheric deposition on leaves is another vector of Cd contamination, and it remains unclear how Zn application affects the allocation of such Cd. We conducted an experiment where the flag leaves of rice plants were treated with solutions with various Zn concentrations and a constant Cd concentration. The 111 Cd stable isotope was used to trace the flux of foliar-applied Cd. Higher levels of foliar-applied Zn enhanced Cd efflux and grain allocation. This is attributed to limited sequestration of foliar-applied Cd in the leaf cell symplasm and increased Cd desorption from leaf cell walls when a high Zn 2+ concentration occurs in the apoplast . Nonionic Zn oxide nanoparticles mitigated these effects. Additionally, the expressions of OsLCT1 and OsZIP7 in flag leaves and OsHMA2 and OsZIP7 in the uppermost nodes were upregulated under high-Zn 2+ treatment, which may facilitate Cd phloem loading and grain allocation. Caution is advised in using foliar Zn in areas with high atmospheric Cd due to potential grain-contamination risks.
Pan Lixiang,Feng Xiaoxiao,Jing Jing,Zhang Jingcheng,Zhuang Ming,Zhang Yun,Wang Kai,Zhang Hongyan
The mixed application of pesticides and foliar fertilizer has been widely used in the production of cucumber, however, their effects on plant growth and pesticide dissipation are still unclear. In this study, the effects of mixed application of pymetrozine, tebuconazole and foliar fertilizer on the cucumber plant growth and pesticide dissipation were investigated simultaneously. The results show that the mixed use of pymetrozine, tebuconazole, especially adding foliar fertilizer, improved the physiological indexes (i.e., area, nitrogen content and chlorophyll content of the leaves, and root growth) of cucumber plants compared to those with the application of single pesticide. Meanwhile, it can significantly affect the dissipation of pymetrozine even in the slower growth matrices (lower leaves, stems, and plants). The residue of tebuconazole in cucumber plants was affected by the combination of formulation type and foliar fertilizer. This study can provide data for scientifically guiding the mixed application of pesticide and fertilizer.
The high loss of foliar-applied fertilizers in the wet season and other extreme weather conditions reduces fertilizer use efficiency remarkably low. Emerging nano-iron materials, owing to their highly desirable properties such as exceptionally small size, particle surface and interface attributes, strong adhesion and high iron ratio, could overcome the limitations of traditional fertilizers. However, their anti-leaching property, leaching resistance mechanism, iron nutrition enrichment capacity and cost effectiveness remain unclear. In this study, four nano-iron materials (Fe nanoparticles (Fe-NPs), Fe 3 O 4 -NPs, α-Fe 2 O 3 -NPs and γ-Fe 2 O 3 -NPs) were compared with traditional iron fertilizers (FeSO 4 and Fe-EDTA). The results showed that the efficiency of traditional iron fertilizers decreased greatly under simulated rainfall conditions due to their poor leaching resistance. In contrast, nano-iron fertilizers performed exceptionally well under simulated rainfall conditions with significant increase in leaf iron concentration, photosynthesis and growth of peanut. This was mainly attributed to their decreased contact angle, increased wetting capacity and increased adhesion on plant surface, which collectively decreased fertilizer leaching remarkably. The adhesion capacity of Fe 3 O 4 -NPs (53.5 mN/m), was nearly three times that of traditional iron fertilizer (18.3 mN/m). Therefore, only a small amount of Fe 3 O 4 -NPs (4 mg/plant) was needed relative to traditional iron fertilizers (FeSO 4 , 59 mg/plant) to achieve comparable high leaf Fe concentration (1076.96 μg/g) under rainfall conditions. Cost evaluation suggests that the cost-competitiveness of Fe 3 O 4 -NPs will become comparable to that of FeSO 4 when its price comes down from the current cost of $139/kg to $36/kg, the cost of FeSO 4 , which is likely considering the pace of nano-material technology development. Together, these results demonstrate the remarkable potential of nano-iron fertilizers in mitigating the escalating fertilizer cost and improving the environmental outcomes of peanut, as well as potentially other crops grown in wet season.
危险品化学品经营许可证（带存储）