Garnet secondary ion mass spectrometry oxygen isotopes reveal crucial roles of pulsed magmatic fluid and its mixing with meteoric water in lode gold genesis.

SignificanceThere is a common consensus that lode gold deposits mostly precipitated from metamorphic fluids via fluid boiling and/or fluid-rock interaction, but whether magmatic hydrothermal fluids and the mixing of such fluids with an external component have played a vital role in the formation of lode gold deposits remains elusive. We use garnet secondary ion mass spectrometry oxygen isotope analysis to demonstrate that the world-class Dongping lode gold deposit has been formed by multiple pulses of magmatic hydrothermal fluids and their mixing with large volumes of meteoric water. This study opens an opportunity to tightly constrain the origin of lode gold deposits worldwide and other hydrothermal systems that may have generated giant ore deposits in the Earth's crust.

Effects of different sowing dates on biomass allocation of various organs and allometric growth of Fagopyrum esculentum.

Introduction: The sowing date plays a crucial role in influencing the growth and reproduction of plants, with its specific impact on biomass allocation and allometric growth remaining unclear. Understanding these effects is essential for optimizing agricultural practices and enhancing crop productivity. Methods: To investigate the effects of sowing dates on biomass allocation and allometric growth, a field experiment was conducted with sequential sowings of Fagopyrum esculentum from April 12th to August 11th in 2018. Biomass measurements were taken across various plant organs, and corresponding allocation calculations were made. A detailed analysis of the allometric growth relationship involving organ biomass variations was performed. Results: The study revealed that the accumulation and allocation of organ biomass in buckwheat were significantly impacted by the sowing dates. Delayed planting led to reduced vegetative growth and increased biomass allocation towards reproduction. Allometric parameters such as exponent, constant, and individual size of buckwheat were notably affected by delayed planting. Interestingly, the allometric exponents governing the relationships between reproductive vs. vegetative biomass and belowground vs. aboveground biomass exhibited varying trends across different sowing dates. Discussion: Notably, late sowings resulted in significantly higher reproductive biomass compared to early and middle sowings. These findings highlight the nuanced relationship between plant size and reproductive biomass under different sowing dates, emphasizing the critical role of planting timing in shaping mature plant sizes and reproductive outcomes. The study underscores the importance of considering sowing dates in agricultural practices to optimize plant growth and productivity.

Observed Changes of Rain-Season Precipitation in China from 1960 to 2018.

Precipitation during the main rain season is important for natural ecosystems and human activities. In this study, according to daily precipitation data from 515 weather stations in China, we analyzed the spatiotemporal variation of rain-season (May-September) precipitation in China from 1960 to 2018. The results showed that rain-season precipitation decreased over China from 1960 to 2018. Rain-season heavy (25 ≤ p < 50 mm/day) and very heavy (p ≥ 50 mm/day) precipitation showed increasing trends, while rain-season moderate (10 ≤ p < 25 mm/day) and light (0.1 ≤ p < 10 mm/day) precipitation showed decreasing trends from 1960 to 2018. The temporal changes of precipitation indicated that rain-season light and moderate precipitation displayed downward trends in China from 1980 to 2010 and rain-season heavy and very heavy precipitation showed fluctuant variation from 1960 to 2018. Changes of rain-season precipitation showed clear regional differences. Northwest China and the Tibetan Plateau showed the largest positive trends of precipitation amount and days. In contrast, negative trends were found for almost all precipitation grades in North China Plain, Northeast China, and North Central China. Changes toward drier conditions in these regions probably had a severe impact on agricultural production. In East China, Southeast China and Southwest China, heavy and very heavy precipitation had increased while light and moderate precipitation had decreased. This result implied an increasing risk of flood and mudslides in these regions. The advance in understanding of precipitation change in China will contribute to exactly predict the regional climate change under the background of global climate change.

Trade-off relationship and internal mechanism of plant leaf size and number in Hulunbuir grassland, China.

The trade-off between leaf size and number is the basis for plant growth strategies. It is of great significance to study the underlying mechanism of leaf size and number trade-offs for well understanding plant growth strategies. In this study, leaf size was expressed by the dry mass of single leaf, while leafing intensity was expressed by the number of leaves per unit stem volume. We used standardized major axis regression analysis method to examine the trade-off relationship between leaf size and number in Hulunbuir grassland. There was a significant negative isometric-growth trade-off between leaf size and number in Chenqicuogang (typical steppe) and Chenqibayi (meadow steppe). There was a significant negative allometric-growth trade-off between leaf size and number in Xeltala (meadow steppe). The underlying mechanism of the relationship between leaf size and number depended on the leaf and stem biomass allocation mechanism and the changes of the stem tissue density.

Phenotypic plasticity of four Chenopodiaceae species with contrasting saline-sodic tolerance in response to increased salinity-sodicity.

It is unknown whether phenotypic plasticity in fitness-related traits is associated with salinity-sodicity tolerance. This study compared growth and allocation phenotypic plasticity in two species with low salinity-sodicity tolerance (Chenopodium acuminatum and C. stenophyllum) and two species with high salinity-sodicity tolerance (Suaeda glauca and S. salsa) in a pot experiment in the Songnen grassland, China. While the species with low tolerance had higher growth and allocation plasticity than the highly tolerant species, the highly tolerant species only adjusted their growth traits and maintained higher fitness (e.g., plant height and total biomass) in response to increased soil salinity-sodicity, with low biomass allocation plasticity. Most plasticity is "apparent" plasticity (ontogenetic change), and only a few traits, for example, plant height:stem diameter ratio and root:shoot biomass ratio, represent "real" plasticity (real change in response to the environment). Our results show that phenotypic plasticity was negatively correlated with saline-sodic tolerance and could be used as an index of species sensitivity to soil salinity-sodicity.

Responses of soil specific enzyme activities to short-term land use conversions in a salt-affected region, northeastern China.

Soil enzyme activity is a sensitive indicator of soil quality changes. The response of soil enzyme activity to different land uses is important in addressing the issues of agricultural sustainability. The objectives of this study were to investigate the effects of short-term land use conversions on soil specific enzyme activity (per unit microbial biomass carbon) of sodic soils and compare the responses of soil absolute (per unit soil mass) and specific enzyme activities in northeastern China. Four specific enzyme activities, including catalase, invertase, urease and alkaline phosphatase were assayed at 0 to 20 cm depth under five land uses, including cropland (CL), alfalfa perennial forage (AF), monoculture grassland (AG), monoculture grassland for hay once a year (AG + M) and successional regrowth grassland (RG). The specific activities of catalase, urease and alkaline phosphatase at 10 to 20 cm depth were 117.3%, 40.0% and 35.6% higher than that in 0 to 10 cm depth, irrespective to the land uses. Conversion of cropland to re-vegetation land increased the specific activities of catalase (2.8%), invertase (99.0%), urease (14.3%) and alkaline phosphatase (14.0%). Under land uses of AF, AG + M, AG and RG, the geometric mean (0.2%, 32.8%, 65.7% and 24.3%, respectively) and sum (2.6%, 38.0%, 82.8% and 29.6%, respectively) of specific enzyme activities at 0 to 20 cm depth were higher than that under CL treatment. The soil specific enzyme activities showed the better discrimination to different land uses than the soil absolute enzyme activities. In conclusion, re-vegetation has a positive effect on the improvement of soil enzyme activity in northeastern China, and the responses of soil specific enzyme activities to short-term land-use conversions are more obvious than the absolute enzyme activities, which could be used as s suitable and sensitive indicator of land use change in semiarid agroecosystems.