Selenium Uptake by Lettuce (Lactuca sativa L.) and Berseem (Trifolium alexandrinum L.) as Affected by the Application of Sodium Selenate, Soil Acidity and Organic Matter Content

Effects of Selenium-Enriched Rape Returning Amount on Available Selenium Content in Paddy Soil and Selenium Accumulation in Rice

Selenium-rich rape "Selenium Ziyuan No.1" was used as green manure to study the effects of different amounts of green manure returned to the field on the release characteristics of available selenium in acidic paddy soil in southern China, and to analyze the absorption and transformation of selenium in rice, so as to provide a theoretical basis for planting natural selenium-rich rice in acidic areas of southern China. Six treatments with different amounts of selenium-enriched rapeseed returning (0, 5, 10, 15, 20, and 25 t/hm²) were set up. Two rice varieties (selenium-rich rice variety Meixiangzhan 2 and common rice variety Zhongguangxiang 1) were selected. The results showed that (1) with the increase of selenium-rich rapeseed returning amount, the available selenium in soil showed an increasing trend. Over time, soil available selenium showed a significant increasing trend, and the content of soil available selenium reached the maximum at tillering stage, and then decreased. (2) For selenium-rich varieties, when the amount of selenium-rich rapeseed returned to the field was less than 15 t/hm², the selenium content in rice grains increased significantly with the increase of the amount of selenium-rich rapeseed returned to the field, then remained basically stable. For conventional varieties, with the increase of the amount of selenium-rich rapeseed returned to the field, the selenium content of rice grains showed an increasing trend, but the overall selenium content was much lower than that of selenium-rich variety. (3) With the increase of the amount of rapeseed returned to the field, the rice yield had an increasing trend, but the maximum rice yields appeared when the amount of selenium-rich rapeseed returned to the field was 15 t/hm². Therefore, Se-enriched rape returning could promote the release of available selenium in soil and the enrichment of selenium in rice plants, and significantly increase the selenium content in rice. According to the selenium content and yield of rice, it is suggested that the selenium-rich rice variety Meixiangzhan 2 was chosen and the amount of Se-rich rape returning is 15 t/hm².

Effects of revetments on soil ecosystems in the urban river-riparian interface

By altering material and energy exchange between river and riparian, the city revetments have an unknown impact on the service function of river-riparian interface (RRI) ecosystems. This study analyzes the differences in natural, permeable (PR), and impervious revetment (IR). We found that the water-filled porosity of revetment increased from 20% to 100%, which coincided with an increase in soil potassium, air-filled porosity, the surface soil of moisture and organic matter (SOM), and a decrease in soil nitrogen, phosphorus nutrients, and in the middle and deep soil SOM. The changes affected the abundance of dominant bacterial and fungi genera. Compared with the PR, surface soil moisture, pH, and underground biomass were lower in IR surface soils, while surface soil SOM and middle soil moisture were higher. This research provides a development direction and theoretical basis for future urban planning and environmental governance.

Egyptian Clover Genotypic Divergence and Last Cutting Management Augment Nutritive Quality, Seed Yield and Milk Productivity

Under a changing climate, harvesting management and exploiting the genotypic divergence of Egyptian clover cultivars offers a biologically viable solution to sustainably boost the milk productivity of dairy animals. Two multi-season field trials were executed under semi-arid conditions whereby the first experiment aimed to assess the potential of Egyptian clover cultivars (Berseem Agaiti, Anmol and SB-11) for nutritional quality attributes and the digestibility of green forage and hay, forage palatability and milk productivity of buffaloes fed on hay. In the second field investigation, new promising line, SB-11, was tested for seed production potential under varying dates of the last harvesting regimes (10, 20 and 30 March along with 9 April and 19 April) owing to a sharp hike in temperature. In terms of the nutritive value of green forage and hay, SB-11 remained superior for recording the maximum crude protein (CP), ash, fat and nitrogen-free extract except dry matter (DM) content that was exhibited by the Anmol cultivar. Additionally, SB-11 remained unmatched by giving a minimum crude fiber (CF), while Berseem Agaiti yielded the lesser nutritive forage by producing 4% and 2% higher CF than SB-11 and Anmol, respectively. Moreover, SB-11 recorded the maximum digestibility of CP and DM. Furthermore, SB-11 exhibited a 6% and 9% higher palatability along with 8% and 11% higher milk production than Anmol and Berseem Agaiti, respectively. Additionally, 20 March surpassed the rest of the cutting dates by exhibiting 7%, 23%, 50% and 207% more seed yield than 10 March, 30 March, 9 April and 19 April, respectively, indicating quite a pronounced effect of the last cutting management on the seed production potential of Egyptian clover. The research findings suggest SB-11 as a promising genotype for bridging the nutritive gap of quality feed (forage and hay) for buffaloes along with addressing the seed production challenge of Egyptian clover.

Distribution of Selenium in the Soil–Plant–Groundwater System: Factors Controlling Its Bio-Accumulation

Selenium (Se) is an essential micronutrient for humans and animals, but both Se excess and deficiency can cause various health risks. Since Greece is among the European countries where people have very low Se-serum, the present study is focused on the Se distribution in cultivated and non-cultivated plants and relative soil coming from the Neogene basins of Greece (Assopos-Thiva and Attica), aiming to define potential Se-source/es and factors controlling Se bio-accumulation and enrichment in food. The dry weight Se values are relatively low (0.1–0.9 mg/kg) with the highest Se contents in garlic, beet and lettuce from the Assopos basin, where the translocation percentage [(mplant/msoil) × 100] for Se, P and S is much higher compared to non-cultivated Attica basin. There is a diversity between the Se source in soil and coastal groundwater which is used for irrigation in the cultivated Assopos–Thiva basin. The soil pH and oxidizing conditions (Eh) are considered the main driving force to make Se available for plant uptake. Potential sources for Se in Greece are Fe-Cu-Zn-sulphide ores and peat deposits in northern Greece, with a Se content ranging from decades to hundreds of mg/kg. Application of the leaching testing protocol is necessary to select the most appropriate proportion of additives to improve the Se deficiencies in agricultural soil.