New metabolites in the degradation of alpha- and gamma-hexachlorocyclohexane (HCH): pentachlorocyclohexenes are hydroxylated to cyclohexenols and cyclohexenediols by the haloalkane dehalogenase LinB from Sphingobium indicum B90A

Technical hexachlorocyclohexane (HCH) and lindane are obsolete pesticides whose former production and use led to widespread contaminations posing serious and lasting health and environmental risks. Out of nine possible stereoisomers, alpha-, beta-, gamma-, and delta-HCH are usually present at contaminated sites, and research for a better understanding of their biodegradation has become essential for the development of appropriate remediation technologies. Because haloalkane dehalogenase LinB was recently found responsible for the hydroxylation of beta-HCH, delta-HCH, and delta-pentachlorocyclohexene (delta-PCCH), we decided to examine whether beta- and gamma-PCCH, which can be formed by LinA from alpha- and gamma-HCH, respectively, were also converted by LinB. Incubation of such substrates with Escherichia coli BL21 expressing functional LinB originating from Sphingobium indicum B90A showed that both beta-PCCH and gamma-PCCH were direct substrates of LinB. Furthermore, we identified the main metabolites as 3,4,5,6-tetrachloro-2-cyclohexene-1-ols and 2,5,6-trichloro-2-cyclohexene-1,4-diols by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In contrast to alpha-HCH, gamma-HCH was not a substrate for LinB. On the basis of our data, we propose a modified gamma-HCH degradation pathway in which gamma-PCCH is converted to 2,5-cyclohexadiene-1,4-diol via 3,4,5,6-tetrachloro-2-cyclohexene-1-ol and 2,5,6-trichloro-2-cyclohexene-1,4-diol.     

Empirical relationships for soil organic carbon transport from agricultural watersheds in Ohio

Improved quantification is needed for long‐term soil organic carbon (SOC) transport in runoff at watershed scales. Coshocton wheel samplers were used to collect runoff samples from no‐till and chisel‐till watersheds in corn (Zea mays) and soybean (Glycine max) rotations over 13 years. Samples were analyzed for SOC, N, P, K, and soil losses. The SOC losses, ranging from 0 to 357 kg ha⁻¹ event⁻¹, were correlated (r² = 0·80–0·94) in power law relationships with N, P, K, soil loss, and runoff. Two events occurring in corn when soybean and cover crop residue were present in no‐till had combined SOC transport of 460 kg ha⁻¹, nearly double the no‐till losses of a previous 11‐year period and 20 times higher than chisel‐till in the same events. Infrequent, extreme transport events that are not well characterized empirically, particularly in no‐till, can strongly influence hydrologic C transport from agriculture watersheds. Copyright © 2007 John Wiley & Sons, Ltd.     

Tillage effects on physical properties of agricultural organic soils of north central Ohio

Drainage, tillage, and intensive land use lead to drastic alterations in physical characteristics of organic soils. As decomposition and soil formation progress, bulk density (ρ_b) increases and total porosity (f_t) decreases due to subsidence, shrinkage, and mineralization of soil organic matter (SOM). However, the rate of subsidence and the changes in soil properties differ among management systems. Thus, the objectives of this study were to determine the effects of different tillage practices on ρ_b and f_t of cultivated peat soils. These experiments were conducted during 2004–2005, on Histosols in north central Ohio. Soil core samples were obtained from experimental plots managed with moldboard plow (MB), no-till (NT), or left bare (B). Conversion of plow tillage to NT increased ρ_b from 0.52 to 0.57 Mg m⁻³, and decreased f_t from 0.72 to 0.70 m³ m⁻³.     

Effect of Predominant Integrated Nutrient Management Practices on Soil Quality Indicators and Soil Quality Indices under Post Monsoon (Rabi) Sorghum (Sorghum Bicolor) in Rainfed Black Soils (Vertisols) of Western India

A long-term study was conducted to study the impact of integrated nutrient management on soil quality in post-monsoon sorghum (Sorghum bicolor) at Solapur in Maharashtra State in Western India under All India Coordinated Research Project for Dryland Agriculture. The experiment was laid out with ten Integrated Nutrient Management Treatments in a randomized block design with three replications. The results of the study indicated that among all the integrated nutrient management treatments practiced, the application of 25 kg nitrogen (N) ha^?1 through crop residue (CR) + 25 kg N ha^?1 (urea) showed the highest soil quality index of 2.36, which was at par with other treatments receiving farmyard manure (FYM) and crop residues along with urea. The relative order of performance of the integrated nutrient management treatments in influencing soil quality was: T₆: 25 kg N ha^?1 (CR) + 25 kg N ha^?1 (urea) (2.36) >T₅: 25 kg N ha^?1 (FYM) (2.31) > T₇: 25 kg N ha^?1 (FYM) +25 kg N ha^?1 (urea) (2.30) = T₈: 25 kg N ha^?1 (CR) +25 kg N ha^?1 (Leucaena loppings) (2.30) > T₁₀: 25 kg N ha^?1 (Leucaena loppings) +25 kg N ha^?1 (urea) (2.17) > T₄: 25 kg N ha^?1 (CR:crop residues) (2.16) > T₉: 25 kg N ha^?1 (Leucaena loppings) (2.15) > T₃: 50 kg N ha^?1 (urea) (2.10) > T₂: 25 kg N ha^?1 (urea) (1.99) > T_1: 0 kg N ha^?1 (control) (1.77). The results of the study also indicated that average percent contribution of each soil key indicator towards soil quality indices was: pH (3.97%), EC (1.94%), organic carbon (18.6%), available P (2.80%), available K (6.57%), exchangeable Ca (7.02%), available S (3.45%), Available Zn (17.9%), dehydrogenase (DHA) (16.2%), microbial biomass carbon (MBC) (18.5%) and mean weight diameter (MWD) (3.14%). Thus, the results of the present study will be highly useful to the land managers in planning effective management of soil quality.     

Effect of Graded Levels of Surface Crop Residue Application Under Minimum Tillage on Carbon Pools and Carbon Lability Index in Sorghum (Sorghum bicolor (L.) Moench)-Cowpea (Vigna unguiculata) System in Rainfed Alfisols

A long term experiment (2005–2012) was conducted in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm of Central Research Institute for Dryland Agriculture, Hyderabad, India. The aim of this experiment was to study the long-term impacts of graded levels of surface crop residue application on carbon (C) pools, aggregate associated C, C lability index and their relationship with crop yield. The experiment was conducted in a randomized block design (RBD) with minimum tillage (MT). Experimental treatments comprised of four levels of surface application of sorghum crop residues (@ 0, 2, 4 and 6 t ha^?1). The test crops, sorghum and cowpea, were grown in rotation yearly. Based on the pooled analysis of long term data (2005–2012), the study revealed that the surface application of sorghum residue @ 6 t ha^?1 and 4 t ha^?1 recorded 21% and 16% higher sorghum grain yields, respectively over control (no residue) whereas, the corresponding increase in the cowpea yield was 50% and 60%, respectively. Besides, the concentrations of soil organic carbon (SOC), inorganic carbon (IC), total carbon (TC), particulate organic carbon (POC) in the top surface soil (upper layer, 0–5cm depth) were found significantly higher than the sub-surface soil (lower layers, 5–15 cm depth) in all the treatments. Storage of soil C was assessed in soil aggregates fractions, and it was found that the smaller size aggregate fractions (0.053mm) contained significantly (p = 0.05) higher content of SOC compared to the large sized fractions (2 mm). The amount of very labile fraction of C extracted with 12 N H₂SO₄ was significantly higher (1.04 g kg^?1) with the application of sorghum stover @ 6t ha-¹ compared to other residue level treatments, in the 0-5 cm soil layer. The Lability Index (LI) increased with the increase in the amount of residues applied and was significantly higher in the surface soils compared to subsurface soil. The results of this study will be highly relevant and of significant value from the view point of managing SOC and its different pools in soil under abiotically stressed semiarid tropical Alfisols soils.     

Semen characteristics and biochemical composition of cloacal foam of male Japanese quails (Coturnix coturnix Japonica) fed diet incorporated with selenium

An attempt was made to investigate the effect of dietary selenium (Se) on physical and cloacal gland size, foam production, biochemical composition of foam and semen biochemical characteristics of male Japanese quail (Coturnix coturnix Japonica). Two hundred twenty‐five (225)‐day‐old male Japanese quail were randomly distributed to three dietary treatment groups for a period of 20 weeks. Each treatment comprised of three replicates, each containing 25 chicks. Three experimental diets were supplemented with 0, 0.5 and 1.0 mg Se/kg (T₁, T₂ and T_3, respectively), and diet T₁ was considered as control. Sodium selenite was used as the source of selenium. All the birds were provided with feed and water ad libitum. Cloacal foam characteristics, that is cloacal gland index and foam weight, were significantly higher in T₂ group. However, body weight, frequency of foam discharge and testes weight (left and right) did not differ significantly (p > 0.05). Physical characteristics of semen, that is semen volume and sperm concentration, did not differ (p > 0.05) among the Se‐treated groups. The sperm motility, live–dead count and abnormality improved significantly (p < 0.05) in 0.5 mg/Se‐supplemented group compared to 0 or 1.0 mg/Se‐supplemented groups. Similarly, fertility and hatchability percentages were higher (p < 0.05) in 0.5 mg/Se‐supplemented group than in control or 1.0 mg/Se‐supplemented counterparts. The biochemical characteristics of foam in terms of total protein, acid phosphatase (ACP) and nitric oxide did not differ (p > 0.05), while the concentration of glucose was higher (p < 0.05) in 0.5 mg/Se‐supplemented diet. On the other hand, alkaline phosphatase (ALP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were lower (p < 0.05) in 0.5 mg/Se‐supplemented group compared to control or 1.0 mg/Se‐supplemented groups. From this study, it was concluded that supplementation of 0.5 mg Se/kg diet was beneficial for foam variables, biochemical composition of foam, semen characteristics and fertility in male Japanese quail.     

Phytosanitary risk of bruchids in lentil imported into India

Import of lentil grain for various purposes involves an inherent risk of introducing exotic pests. There are 26 seed pests reported on lentil including 18 bruchids, of which 12 have not yet been reported from India. These may be transported across geographical boundaries as hidden infestations of imported lentil grain. An attempt has been made to analyse the literature, according to the relevant ISPMs, to provide scientific justification of the relevant phytosanitary measures applied in India. The various aspects of risk analysis considered were: initiation (compilation of world pest record and identification of pathway), risk assessment (ascertaining pest status, pest distribution, damage, host range, etc.) and risk management (pest exclusion) through X-ray radiography, thermal and insecticidal treatments. The repeated detection of bruchids in imported breeding material of lentil ( Acanthoscelides obtectus , Bruchus ervi , Bruchus lentis , Callosobruchus analis , Callosobruchus chinensis and Callosobruchus maculates ) highlights their potential phytosanitary importance in bulk imports. Analysis of risk prior to import is the first step in this direction.     

Synthesis of new 7H-1,3,4-thiadiazolo[3,2-a] [1,3,5] triazine-7-thiones as potential fungicides

A number of 2-aryl- and 2-aryloxymethyl-5-aryl-7H-1,3,4-thiadiazolo[3,2-a][1,3,5]triazine-7-thiones have been synthesised and their fungitoxicities determined in vitro against Aspergillus niger and Fusarium oxysporum. Two alternative routes for synthesis of the title compounds are described. Some of the compounds had activities comparable with that of the commercial fungicide mancozeb. Structure/activity relationships for the compounds are discussed.