Soil Salinity Status under Post-Irrigation Conditions at the Generalovskaya Irrigation System in Volgograd Oblast

Eurasian Soil Science - The aim of this work is to evaluate recent changes in soil salinity status at the Generalovskaya irrigation system in the dry-steppe zone of Volgograd oblast of Russia on...     

The Hymenopteran parasitoid complex associated with Coniesta ignefusalis (Hampson) (Lepidoptera: Crambidae) on Pearl millet in Mali

Phytoparasitica - Moths of Coniesta ignefusalis (Hampson) were collected by automatic light traps on millet field near Bamako in 2018. The light trap data shows three periods of moth flight. The...     

Comparison of Different Glycerol and Egg Yolk Concentrations Added to Tris‐based Extender for the Collared Peccaries (Tayassu tajacu) Semen Freezing

This study aimed to evaluate various concentrations of egg yolk (5, 10, or 20%) in combination with different concentrations of glycerol (3% or 6%) added to a Tris‐based extender on the post‐thaw characteristics of sperm obtained from Tayassu tajacu. For this purpose, semen from 10 sexually male mature collared peccaries was collected by electroejaculation and evaluated for sperm motility, vigour, viability, morphology and functional membrane integrity. The ejaculates were initially extended in Tris‐fructose plus egg yolk (5%, 10% or 20%). After cooling, the semen was added to Tris‐egg yolk plus glycerol (6% or 12%), resulting in a final concentration of 3% or 6% glycerol of the extender. Straws were frozen using liquid nitrogen and thawed in a water bath at 37°C for 30 s. The frozen–thawed semen was evaluated as reported for fresh semen. After thawing, a significant decrease was verified for sperm motility and vigour, for all the samples in comparison with fresh semen. However, no differences were evidenced among treatments for any sperm characteristics evaluated (p > 0.05), except for the combination between 10% egg yolk and 6% glycerol, which provided the worst preservation of functional membrane integrity (p < 0.05). The interactions between higher concentrations of egg yolk (20%) and glycerol (6%) and also between lower concentrations of the same substances (5% egg yolk and 3% glycerol) added to the Tris‐based extender negatively affected the preservation of the normal sperm morphology after thawing (p < 0.05). In conclusion, the use of Tris‐based extender added to 10% or 20% egg yolk plus 3% glycerol is recommended for effective sperm cryopreservation in collared peccaries.     

Seven invasive owlet moths (Lepidoptera: Noctuidae) in Israel and their potential parasitoids (Hymenoptera: Chalcidoidea)

Invasive tropical Noctuidae pest species collected in Israel included Spodoptera mauritia (Boisduval), Trichoplusia vittata (Wallengren), Anomis flava (Fabricius), Anomis sabulifera (Guenée), Earias vittella (Fabricius), Earias biplaga Walker, and Earias cupreoviridis (Walker). All seven noctuid species were rare and sporadically present only along the coastal plain. Possible reasons for this type of distribution are discussed. Abundance was greatest in May with smaller peaks present in February–March and September. Several common parasitoid species – Elasmus flabellatus (Fonscolombe), Elasmus nudus (Nees) and Elasmus viridiceps Thomson (Hymenoptera: Eulophidae), with potential as biological control agents for tropical noctuids, are detected in Israel.     

Water resources are the limiting favor in growing soybeans in rice crop rotations

It is shown that under conditions of Kalmykia when growing soybean in rice crop rotations, it is possible to form a stable yield of this crops up to 1.65 t/ha with consideration of the regularities of its growth and development along with the dynamics of saving resources.     

典型黑土区村级尺度侵蚀沟演变

侵蚀沟的演变是东北水土流失过程的重要方面.利用1968和2009年亚米级遥感影像,获取典型黑土区村级尺度的侵蚀沟分布、耕地垄向和土地利用数据,基于1∶1万地形图获取等高线、坡度、坡长和垄向坡度数据,在地理信息系统和遥感技术的支持下,分析典型黑土区41 a村级尺度侵蚀沟的动态变化及其影响因素.结果表明:1)41 a间,典型黑土区侵蚀沟密度有明显增加的趋势,基于分辨率为亚米级遥感影像解译的侵蚀沟密度较以往研究结果大幅增加;2)自然坡度0.25°～1.5°范围内为该区域侵蚀沟密度变化最大的区域,8°以上区域由于实施退耕还林措施,侵蚀沟密度降低;3)300～500 m坡长区域侵蚀沟密度出现极值;4)由于实施改垄措施,41 a后垄向坡度在0～0.25°范围内耕地面积增加,大于0.25°范围内耕地面积均减少.     

Experimental determination of the active organic matter content in some soils of natural and agricultural ecosystems

In incubation experiments, the soil supply with carbon of mineralizable (C_min), potentially mineralizable (C_pm), and active (C_ac) organic matter, and of microbial mass (C_mb) in natural and agricultural ecosystems of Moscow region (gray forest soil) and Catalonia (Xerochrept) was assessed based on the measurements of the C-CO₂ emission. In the gray forest soil, the C_pm and C_ac contents decreased in the following sequence of ecosystems: forest > meadow > unfertilized agrocenosis; in the Xerochrept, forest > pasture > scrub > agrocenoses with organic fertilizer > unfertilized agrocenosis. A method for measurement of the C_mb according to the C-CO₂ emission during an 11-to 14-day incubation of previously dried soils is proposed.     

Pore-scale view of microbial turnover: Combining 14C imaging, μCT and zymography after adding soluble carbon to soil pores of specific sizes

The location of microorganisms and substrates within soil pore networks plays a crucial role in organic carbon (C) processing, and its microbial utilization and turnover, and has direct consequences for C and nutrient cycling. An optimal approach to quantify responses to new C inputs from microorganisms residing in specific pores is the addition of new C to pores of target sizes in undisturbed soil cores. We used the matric potential approach to add ¹⁴C-labelled glucose to small (< 40 μm, root free) or large (60–180 μm, potentially inhabited by roots) pores of undisturbed soil cores. Localization of glucose-derived C via ¹⁴C imaging was related to pore size distributions and connectivity, characterized via X-ray computed microtomography (μCT), and to β-glucosidase activity, characterized via zymography. After 2-week incubations, 1.3 times more glucose was mineralized (¹⁴CO₂) when it was added to the large pores; however, more ¹⁴C remained in microbial biomass when glucose was added to the small pores. Consequently, although utilizing the same amounts of easily available C, the microorganisms localized in the large pores had faster turnover compared to microorganisms in small pores. Stronger associations between β-glucosidase activity and glucose-derived C were observed when glucose was added to the large pores. We conclude that (a) the matric potential approach allows placing, albeit not exactly, of soluble substrates into pores of target diameter range, and (b) microorganisms localized in large pores respond to new C inputs with faster turnover, greater growth and more intensive enzyme production compared to those inhabiting the small pores.     

Root exudates as an important factor of formation of nanomolecular structures of the rhizosphere

The content and qualitative composition of organic acids and sugars in the rhizosphere of tomato, cucumber, and wheat is investigated. Preservation of their high content in the rhizosphere of vegetable crops with inoculation of the plants with rhizobacteria is shown. The possible influence of this effect on the formation of nanomolecular structures of the rhizosphere is discussed.