Adjusting agronomic measures to alleviate the kernel position effect in maize is important for ensuring high yields. In order to clarify whether the combined application of organic fertilizer and ...chemical fertilizer (CAOFCF) can alleviate the kernel position effect of summer maize, field experiments were conducted during the 2019 and 2020 growing seasons, and five treatments were assessed: CF, 100% chemical fertilizer; OFCF1, 15% organic fertilizer+85% chemical fertilizer; OFCF2, 30% organic fertilizer+70% chemical fertilizer; OFCF3, 45% organic fertilizer+55% chemical fertilizer; and OFCF4, 60% organic fertilizer+40% chemical fertilizer. Compared with the CF treatment, the OFCF1 and OFCF2 treatments significantly alleviated the kernel position effect by increasing the weight ratio of inferior kernels to superior kernels and reducing the weight gap between the superior and inferior kernels. These effects were largely due to the improved filling and starch accumulation of inferior kernels. However, there were no obvious differences in the kernel position effect among plants treated with CF, OFCF3, or OFCF4 in most cases. Leaf area indexes, post-silking photosynthetic rates, and net assimilation rates were higher in plants treated with OFCF1 or OFCF2 than in those treated with CF, reflecting an enhanced photosynthetic capacity and improved post-silking dry matter accumulation (DMA) in the plants treated with OFCF1 or OFCF2. Compared with the CF treatment, the OFCF1 and OFCF2 treatments increased post-silking N uptake by 66.3 and 75.5%, respectively, which was the major factor driving post-silking photosynthetic capacity and DMA. Moreover, the increases in root DMA and zeatin riboside content observed following the OFCF1 and OFCF2 treatments resulted in reduced root senescence, which is associated with an increased post-silking N uptake. Analyses showed that post-silking N uptake, DMA, and grain yield in summer maize were negatively correlated with the kernel position effect. In conclusion, the combined application of 15–30% organic fertilizer and 70–85% chemical fertilizer alleviated the kernel position effect in summer maize by improving post-silking N uptake and DMA. These results provide new insights into how CAOFCF can be used to improve maize productivity.
Due to its small size, large specific surface area and hydrophobicity, microplastics, and the adsorbed contaminants may together cause potential negative effects on ecosystems and human beings. In ...this study, kinetics and size effects on adsorption of Cu(II), Cr(III), and Pb(II) onto PE, PP and PET microplastic particles were explored. Results indicated that the PE and PET microplastics have the higher adsorption capacity for Cu(II), Cr(III), and Pb(II) than that for PP microplastic. The adsorption capacity was affected by microplastic types and metal species. Among the three metals, Pb(II) had the largest adsorption amount on microplastic particles, especially on PET particles. Moreover, the adsorption capacities of microplastics increase with the decrease of particle size. The metal adsorption capacity of <0.9 mm microplastics is greater than that of 0.9–2 mm and 2–5 mm microplastics. The size effect on metal adsorption was largest for PE microplastic. More attention should be paid in case of the coexistence of heavy metals and tiny PE and PET microplastics in the environment.
Microplastics have been proven to be hotspots of bacterial pathogens and antibiotic resistance genes (ARGs). The enrichment of ARGs in microplastisphere, the specific niche for diverse microbial ...communities attached to the surface of microplastic, has attracted worldwide attention. By collecting 477 pairs of ARG abundance data belonging to 26 ARG types, based on the standardized mean difference (SMD) under the random effect model, we have performed the first meta-analysis of the ARG enrichment on microplastics in aquatic environments in order to quantitatively elucidate the enrichment effect, with comparison of non-microplastic materials. It was found that ARGs enriched on the microplastics were more abundant than that on the inorganic substrates (SMD = 0.26) and natural water environments (SMD = 0.10), but lower abundant than that on the natural organic substrates (SMD = −0.52). Furthermore, microplastics in freshwater tended to have a higher degree of ARG enrichment than those in saline water and sewage. The biofilm formation stage, structure, and component of microplastisphere may play a significant role in the enrichment of ARGs.
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•Microplastics may enrich ARGs in aquatic environments.•ARG enrichment for microplastics is in-between inorganic and organic substrates.•Microplastics can enrich more ARGs in freshwater than in saline water or sewage.•Biofilm formation process affects the ARG enrichment in the microplastisphere.
Small-sized microplastics (MPs) pose greater ecological toxicity due to their larger surface area, which makes them more likely to act as carriers for other pollutants and to be ingested by aquatic ...organisms. However, traditional visual analysis often neglects small-sized MPs and their associated ecological risk. This study utilized Laser Direct Infrared (LDIR) spectroscopy and traditional visual analysis to examine MPs in 31 sediment samples from Jinzhou Bay, a typical semi-enclosed bay located at the economic center of Dalian, China. The results showed significant heterogeneity in MP distribution, with averages of 1192 and 2361 items/kg dry weight reported by visual analysis and LDIR spectroscopy, respectively. LDIR spectroscopy identified MPs as small as 10 μm, with the majority of MPs (89.21 %) within the 10–250 μm range, and a significant proportion (46.45 %) between 10 and 50 μm among them. However, visual analysis was limited to detecting MPs >50 μm, and significant portions were identified between 50 and 100 μm (49.36 %) and 100–250 μm (31.01 %), missing a substantial fraction of smaller MPs. The predominant polymers identified were polyamide (PA), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and acrylonitrile butadiene styrene (ABS). LDIR spectroscopy demonstrated a strong positive correlation between MP abundance and clay content, a relationship not observed with traditional visual analysis. The Potential Ecological Risk Index (PERI) indicated that over 87 % of sites posed an extremely high risk according to LDIR spectroscopy, compared to 51 % by traditional visual analysis. These discrepancy underscores the underestimation of ecological risks by traditional methods, particularly for small-sized MPs. High-risk polymers such as polyvinyl chloride (PVC), ABS, and polyurethane (PUR) significantly influenced PERI values. These findings highlight the critical need for precise identification and thorough risk assessment of small-sized MPs in environmental studies and offer insights for understanding of MP vertical migration in aquatic environments, particularly in the context of co-settlement with sediments.
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•LDIR may avoid the overlook of smaller MPs by stereomicroscope.•Ecological risks are underestimated using the traditional visual analysis.•Strong positive correlation between MP and clay content was observed by LDIR.
Improving SO2/H2O resistance at low temperatures is a key challenge for industrial applications of NH3-SCR catalysts. Herein, a novel catalyst with remarkable low-temperature NH3-SCR activity and ...strong SO2/H2O resistance was designed by loading MoOx protective layer over porous kit-CeO2. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupled with basic characterization techniques were utilized to further elucidate the underlying mechanisms, and a dynamic balance between the deposition and decomposition of ammonia bisulfate was captured over porous kit-CeO2. Highly dispersed MoOx species pre-adsorbed with NH3 significantly curtailed the adsorption of NOx molecules, and the catalytic reaction over MoOx/kit-CeO2 primarily followed by the Eley-Rideal mechanism. At 250 °C, in the presence of SO2 and H2O, the Ce-O-Mo pairing site was almost unaffected and the super SO2- and H2O-tolerant property originated from the facilitated decomposition of ammonium bisulfate (ABS) and the shielding effect of Mo protective layer on SO2/H2O. This study provided an important guidance to the application of ceria-based catalysts for environmental control within low-temperature operations in non-power industries such as glass, steel, cement manufacturing, etc.
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•A catalyst with good NH3-SCR activity was designed by loading MoOx over kit-CeO2.•MoOx/kit-CeO2 shows strong SO2/H2O resistance.•The NH3-SCR reaction primarily followed by the Eley-Rideal mechanism.•MoOx/kit-CeO2 can facilitate decomposition of ammonium bisulfate.•MoOx protective layer on SO2/H2O shows the shielding effect.
Microplastics (MPs) undergo aging over time, which can influence their behavior in the environment. While laboratory-simulated studies have investigated MP aging, research on natural aging in various ...real environments remains limited. This study aims to investigate the physical, chemical and biological changes that occur in five types of MPs after more than 10 months of natural aging in three different real environments: seawater, air and soil. Results are compared with previous laboratory experiments. The surface roughness of all types of aged MPs was found to be higher in seawater than in air and soil, which differed from previous simulated studies that showed the highest roughness in air. All aged MPs exhibited the occurrence of hydroxyl and carbonyl groups due to the oxidation processes. Interestingly, the MPs aged in soil showed the lowest level of these functional groups, while in seawater or air, some MPs demonstrated the highest. This contrasts with previous studies indicating the highest level of oxygen-containing functional groups in aged MPs in air. Bacterial analysis identified fourteen bacterial phyla on the surface of aged MPs in all three real environments, with varying abundance in specific environments. Notably, the composition of bacterial communities in the microplastisphere was determined by the surrounding environments, independent of MP types. Natural aging is more complex than laboratory simulations, and the degree of MP aging increases with the complexity of environmental factors. These findings enhance our understanding of the natural aging of MPs in different real environments.
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•Complexity of nature induce the disparities of aged MPs with lab-simulations.•More complex environmental factors induce a higher degree of MP aging.•Microplastisphere is determined by aging environments rather than MP types.
Increasing plant density usually increases the intra‐specific competition of maize plants. This study was conducted to determine whether maize (Zea mays L.) hybrid density tolerance is related to ...intra‐specific competition. Field experiments were conducted using a split‐plot design, the main plots contained four maize hybrids, and subplots were 12 plant densities varied from 1.5 to 18 × 104 plants ha−1. This study focused on dry matter accumulation, grain yield (GY), competition intensity (CI), and absolute severity of competition (ASC) based on the above treatments. Among all tested hybrids, GY exhibited a curvilinear response to plant density, which was well characterized by the Steinhart–Hart equation. Maize hybrids differed in optimum GY in descending order as follows: Zhongdan909 (ZD909) > Xianyu335 (XY335) = Yedan13 (YD13) > Zhongdan2 (ZD2). The CI and ASC of tested maize hybrids indicated that intra‐specific competition increased with increasing plant density. In most cases, the CI and ASC of older maize hybrids were higher than those of modern maize hybrids when plant density exceeded 9.0 × 104 plants ha−1. The results showed that the slope of the linear regression of ASC and plant density (i.e., the k‐value) could be used to compare the intra‐specific CI of maize hybrids, and there were significant negative correlations of k‐value with optimum plant density and GY. Intra‐specific competition is negatively correlated with the density tolerance of maize hybrids. This relationship may provide new insights for determining future maize breeding targets.
•The rod drop dynamic of the TMSR – SF1 is investigated by experimental and theoretic analysis.•The efficiency of the driving mechanism is deduced as a relationship with the rod dropping ...velocity.•The calculated rod drop time is satisfied with the limiting fast drop time of the TMSR – SF1.•A hydraulic buffer is designed to alleviate the dropping shock in the scram.
The scram function renders the core subcritical in response to plant upsets, which is realized by fast drop of the control rods. In the solid fuel (SF) thorium molten salt reactor system (TMSR), denoted as the TMSR – SF1 project, the drop time of the rod is obviously affected by the driving mechanical drag and the hydraulic resistance of the liquid environment. An inner-house code is developed to analyze the rod drop in the TMSR – SF1. In the code, the total transmission efficiency of the driving mechanism is deduced as a relationship with dropping velocity of the rod. With the experimental and theoretic analysis, the motion process of the rod drop is simulated in this study. And it turns out that the drop time in the molten salt is satisfied with the limiting drop time in the TMSR – SF1. In addition, a hydraulic buffer is designed to alleviate the dropping shock from the scram and the calculation results are presented in the paper as well.
Cotton (Gossypium hirsutum L.) is characterized by an indeterminate growth habit, and removal of early fruiting forms often elicits compensatory growth. However, no consensus has been reached on the ...response of cotton to removal of fruiting forms. We conducted field experiments in 2010 and 2011 with four different early fruiting branch removal treatments (CK, untreated control; R1, removal of one basal fruiting branch; R2, removal of two basal fruiting branches; and R3, removal of three basal fruiting branches) to explore the effects of removing early fruiting branches on premature senescence, yield, and fiber quality of cotton planted on two planting dates. Our results showed that removing early fruiting branches delayed premature senescence of cotton in terms of chlorophyll content, malondialdehyde content, and peroxidase and superoxide dismutase activities at the mid‐late growth stage, especially with R1 and R2 treatments for early‐planted cotton. Removing early fruiting branches increased the leaf area index, leaf area duration, and net assimilation rate compared with untreated plants, which further increased the dry matter accumulation, yield, and some yield components, and significant differences were observed for the R1 and R2 treatments, especially for early‐planted cotton. However, no significant beneficial effects were observed on fiber quality after removing early fruiting branches. In conclusion, removing one or two early fruiting branches delayed premature senescence and improved yield in early‐planted cotton but did not affect fiber quality. Therefore, it could be an effective practice to incorporate into cotton production.
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