Paedomorphosis in the Ezo salamander (Hynobius retardatus) rediscovered after almost 90 years

Although paedomorphosis is widespread across salamander families, only two species have ever been documented to exhibit paedomorphosis in Hynobiidae. One of these two exceptional species is Hynobius retardatus in which paedomorphosis was first reported in 1924, in specimens from Lake Kuttara in Hokkaido. This population became extinct after the last observation in 1932; since then, no paedomorphs of this species have been reported anywhere. Here, we report the rediscovery of paedomorphs of this species. Three paedomorph-like male salamanders were collected from a pond in the south Hokkaido in December 2020 and April 2021; in size, these specimens were similar to metamorphosed adults but they still displayed larval features such as external gills and a well-developed caudal fin. An artificial fertilization experiment demonstrated that they were sexually compatible with metamorphosed females, thus, confirming them to be paedomorphs. Future efforts to find additional paedomorphs in this and other populations are required to assess the prevalence of paedomorphosis in H. retardatus and to improve understanding of the ecology and evolution of paedomorphisis in Urodela.

Effects of Organic Amendments on Soil Aggregate Stability and Microbial Biomass in a Long-Term Fertilization Experiment (IOSDV)

The effect of two types of organic amendment (manure and straw incorporation) and various doses (0–200 kg N*ha−1) of mineral N fertilization on microbial biomass C (MBC), aggregate stability (AS), soil organic C (SOC) and grain yield were investigated in an IOSDV long-term fertilization experiment (Keszthely, Hungary). This study was conducted during years 2015–2016 in a sandy loam Ramann-type brown forest soil (Eutric Cambisol according to WRB). Organic amendments had a significant effect on AS, MBC and SOC, increased their values compared to the unamended control. The organic amendments showed different effects on AS and MBC. AS was increased the most by straw incorporation and MBC by manure application. The magnitude of temporal variability of AS and MBC differed. Presumably, the different effects of organic amendments and the different degrees of temporal variability explain why there was only a weak (0.173) correlation between AS and MBC. AS did not correlate with SOC or grain yield. MBC correlated (0.339) with SOC but not with the grain yield. The N fertilizer dose did not have a significant effect on AS and MBC, but had a significant effect on SOC and grain yield.

Effects of the Contents of Mineral Elements on Gummosis in Prunus salicina Lindl.

To investigate the relationship between mineral elements and plum gummosis disease, Prunus salicina Lindl. trees with four grades of gummosis were used as the experimental materials. The contents of N, P, K, Ca, Mg, B, Fe, Mn, Zn and Cu in the branches and leaves were measured, and the correlation between mineral elements and gummosis was systemically analyzed through multiple comparisons, binary logistic regression analysis, and ordinal logistic regression analysis. In addition, the effects of prevention and control of the necessary mineral elements on the gummosis disease of P. salicina were verified after a fertilization experiment. The results indicate that the contents of nitrogen and manganese positively correlate with the occurrence of gummosis. In contrast, the contents of calcium and boron significantly negatively correlate with the occurrence of gummosis. A fertilization experiment facilitated the discovery that the control of nitrogen, as well as the increased application of boron and calcium fertilizers, contributed to the prevention and control on gummosis disease in P. salicina

Phosphorus regulates ecosystem carbon dynamics after permafrost thaw

<p>The ecosystem carbon (C) dynamics after permafrost thaw depends on more than just climate change since soil nutrient status may also impact ecosystem C balance. It has been advocated that the potential nitrogen (N) release upon permafrost thaw could promote plant growth and thus offset soil C loss. However, compared with the widely accepted C-N interactions, little is known about the potential role of soil phosphorus (P) availability. Here we combined two-year field observations along a permafrost thaw sequence (constituted by four thaw stages, <em>i</em>.<em>e</em>., non-collapse and 5, 14, and 22 years since collapse) with an in-situ fertilization experiment (included N and P additions at the level of 10 g N m<sup>-2</sup> yr<sup>-1</sup> and 10 g P m<sup>-2</sup> yr<sup>-1</sup>, respectively) in a Tibetan swamp meadow to evaluate ecosystem C-nutrient interactions upon permafrost thaw. Our results showed that changes in soil P availability rather than N availability played an important role in regulating the increases in gross primary productivity and the decreases in net ecosystem exchange along the thaw sequence. The fertilization experiment further confirmed that P addition had stronger effects on plant growth than N addition in this permafrost ecosystem. These two lines of evidence highlight the crucial role of soil P availability in altering the trajectory of permafrost C cycle under climate warming.</p>

Evaluating changes in nitrogen and sulphur content in a soil-plant system in a long-term fertilization experiment

The objective of this study was to evaluate the impact of long term NPK fertilization (considering that S containing superphosphate was supplied for 26 years of experiment, but since 9 years S has not used any longer) on sulphur- and nitrogen content and N/S ratio of winter wheat. The second objective of this work was to determine the changes of the amount of the different nitrogen and sulphur fraction in chernozem soil in a long term fertilization experiment. The third aim of the work was to determine if a relationship could be established between the studied parameters. Based on our results, it can be stated that the sulphur containing superphosphate supplied in the period of 1984-2010 has no longer significant effect on total sulphur content of plant in 2018. The NPK fertilization treatments had positive effect on total nitrogen content of winter wheat. In general, increasing NPK doses resulted in significantly higher nitrogen. The effect of irrigation applied in previous years has no statistically significant effect on the sulphur and nitrogen content of wheat. The wheat grain produced in our experiment, especially in fertilized treatments showed S deficiency. Analysing the changes of CaCl2 soluble nitrate-N and total N of the soil, it can be stated that the effect of increasing fertilizer doses clearly appears in these parameters, because the treatment with increasing fertilizer doses resulted higher CaCl2 soluble N forms compared to the control treatment in soil. These values increased until flowering stage of wheat and after that a slightly decrease was observed as a result of higher N uptake of plant. In overall, it can be stated, that the effect of superphosphate on measured sulphur fraction is prevailed. With increasing fertilizer doses higher sulphate content was detected in soil, but the sulphate content measured in different soil extractant is not enough for the wheat in this experiment area. Studying the correlation between the measured parameters of plant and soil, it can be concluded, that the relationships between nitrogen in the plant and in the soil is stable, and did not change during the growing season. The correlation between plant S and soil S varied in the measured periods and the r value was low in most cases. At the stage of flowering the highest r value was found between KCl-SO4 and plant S. In the stage of ripening the strongest correlation was detected between KH2PO4-SO4 and grain S content.

Simulating the Impact of Long-Term Fertilization on Basic Soil Productivity in a Rainfed Winter Wheat System

Basic soil productivity (BSP) is the ability of a soil, in its normal environment to support plant growth. However, the assessment of BSP remains controversial. The aim of this study is to quantify and analyze the trends of BSP in winter wheat seasons using the decision support system for agrotechnologie transfer (DSSAT) model under a long-term fertilization experiment in the dark loessal soil region of the Loess Plateau of China. In addition, we evaluated the contribution percentage of BSP to yield and its influencing factors. A long-term fertilization experiment with a winter wheat/spring maize rotation was established in 1979 in a field of the Gaoping Agronomy Farm, Pingliang, Gansu, China, including six treatments: (1) no fertilizer as a control (CK), (2) chemical nitrogen fertilizer input annually (N), (3) chemical nitrogen and phosphorus fertilizer input annually (NP), (4) straw return and chemical nitrogen fertilizer input annually plus phosphorus fertilizer added every second year (SNP), (5) manure input annually (M), and (6) M plus N and P fertilizers added annually (MNP). The application of the DSSAT-CERES-Wheat model showed a satisfactory performance with good Wilmott d-index (0.78~0.95) and normalized root mean square error (NRMSE) (7.03%~18.72%) values for the tested genetic parameters of winter wheat. After the 26-years experiment, the yield by BSP of winter wheat under the M and MNP treatment significantly increased, at the rate of 2.7% and 3.82% a year, respectively, whereas that of CK and N treatments significantly decreased, at the rate of 0.23% and 3.03%. Moreover, the average contribution percentage of BSP to yield was 47.0%, 39.4%, 56.3%, 50.0%, and 61.9% in N, NP, SNP, M, and MNP treatments, respectively. In addition, soil organic carbon contents were the main controls of BSP under the different fertilization conditions in the dark loessial soil area. As a result, the combined application of organic fertilizer or straw and chemical fertilizer can be an effective form of fertilization management to greatly enrich basic soil productivity, continually promote the contribution percentage of BSP, and ultimately increase crop yield.