Effect of ammonium sulfate on the phytotoxicity, foliar uptake, and translocation of imazamethabenz in wild oat
Experiments were conducted in greenhouse, growth chamber, and laboratory conditions to determine the effect of ammonium sulfate [(NH4)2SO4] on the phytotoxicity, foliar uptake, and translocation of imazamethabenz on wild oat. Rates of (NH4)2SO4 up to 5% (w/v) applied with a greenhouse sprayer did not affect the phytotoxicity of the herbicide when the mix was applied at the one- to two-leaf stage. However, inclusion of 1 and 2% (NH4)2SO4 increased the phytotoxicity of the herbicide when the mix was sprayed at the two- to three-leaf, or the three- to four-leaf stage. At 10%, (NH4)2SO4 decreased the phytotoxicity of the sublethal dosage of the herbicide. When the herbicide was applied as individual drops to the growth chamber-grown plants, inclusion of (NH4)2SO4 at 1% did not affect phytotoxicity as measured by shoot growth. The presence of (NH4)2SO4 did not affect the amount of imazamethabenz retained by wild oat foliage, but it decreased [14C]imazamethabenz absorption, slightly antagonized acropetal translocation, and increased the basipetal translocation of [14C]imazamethabenz. It was concluded that application methods greatly modify the effect of (NH4)2SO4 on imazamethabenz phytotoxicity. Herbicide absorption and translocation as determined by one method do not necessarily represent the absorption and translocation patterns when different application methods are used. Absorption and translocation were not the factors that were responsible for the observed effect of (NH4)2SO4 on the herbicide phytotoxicity.
Nitrogen and phosphorus removal and physiological response in Zizania latifolia and Sagittaria sagittifolia under different degree of eutrophic water
Two aquatic plants, Zizania latifolia and Sagittaria sagittifolia, were used to study the variation of physiological responses and the water qualities under mild, moderate and weighty eutrophic water in plastic pot scale experiments. The physiological characteristics of both plants were investigated, which included contents of leaf malondialdehyde (MDA) and proline, membrane permeability (MP), and activities of catalase (CAT) and peroxides (POD). The water qualities were analyzed correspondingly. The results showed remarkable effects of different degree of eutrophic water on physiological characteristics of the plants. Compared with mild eutrophic water, increasing degree of eutrophication significantly increased the contents of MDA and MP, decreased POD activity, especially in Zizania latifolia. The proline content increased more evidently in Sagittaria sagittifolia than that in Zizania latifolia, and the CAT activity showed no significant change in both plants. Removals of TN, NH4+-N and TP increased with increasing degree of eutrophication, reaching the highest value 96.5%, 97.2% and 92.7%, respectively, in Sagittaria sagittifolia under weighty eutrophic water. However, Zizania latifolia achieved its highest remove efficiency of TN and NH4+-N under moderate eutrophic water and that of TP under weighty eutrophic water. Besides, TN, NH4+-N and TP removals were higher in Zizania latifolia than those in Sagittaria sagittifolia under mild eutrophic water. These results suggested that Zizania latifolia and Sagittaria sagittifolia were the recommended aquatic plants in phytoremediation of mild and weighty eutrophicated water, respectively.
Soil organic matter and microbiological development of technosols in the South Wales Coalfield
Abstract Degraded land (formerly ‘reclaimed’) after surface-coal-mining is a serious problem in South Wales. This project uses forestation to foster soil development on opencast coal-mine spoil technosols. It compares records of humification and the soil microbiological system (microcoenosis) using paired data from the same plantings in 1998 and 2018. Statistical analysis finds no significant difference between samples collected under trees planted by the pit-planting versus trench planting method or trees planted using organic or mineral fertilizer. However, there are strong significant differences in both soil organic matter and microflora components and significant correlations with time since tree planting. Most components of the soil organic carbon (TOC) and the microflora increase, often significantly. However, compared to 2018, 1998 samples contain significantly greater maximum levels of Insoluble Carbon while the microflora had significantly more Ammonifying bacteria. Decreases in Insoluble Carbon explain the relatively small increase in TOC between 1998 and 2018. The % extracted with 0.1 N H2SO4 is significantly larger in 2018, suggesting active weathering. Similarly, both the maxima and minima of total Humic and Fulvic acids content, extracted with 0.1 M Na4P2O7 + 0.1 M NaOH, are significantly greater in 2018. Total microflora shows significant positive correlations with time-since-tree-planting as do the proportions of bacilli and actinomycetes but the correlation with ammonifying bacteria is negative. In 1998, the microflora was dominated by non-spore-forming bacteria while, in 2018, bacilli and actinomycetes prevail; both are involved in the transformation of complex organic compounds and humification. This indicates active transformation of more complex organic compounds and advancing humification. In sum, forestation of these degraded, formerly reclaimed, opencast coal-mine spoils has resulted in a massive increase in both the size and functioning of the soil organic system.