Physico-chemical changes during vermicomposting of a terrestrial weed, Mikania micrantha and leaf litters of Acacia auriculiformis and Bambusa polymorpha mixed with cowdung

Aim: The aim of the present study was to understand the physico-chemical changes during vermicomposting of terrestrial weeds, Mikania micrantha and leaf litters of Acacia auriculiformis and Bambusa polymorpha mixed with cowdung.Methodology: Vermicomposting was done in 2.5 l earthen pot, each having 300 g waste materials [cowdung alone (300g) and different litter wastes mixed with cowdung in 7:3 ratio]. Based on our pilot study using cowdung and plant wastes in different ratios, it was observed that earthworm thrived well and acted better in 7:3 (plant wastes: cowdung) compared to other ratios. Each pot was inoculated with 30 adult earthworms, Perionyx excavatus [cumulative weight (g) 9.99±0.09] after 21 days of pre-composting of wastes. Samples from vermicomposting pots were collected on 0, 15, 30 and 45th day for physico-chemical analysis of wastes. Results: Vermicomposting brought about changes in pH values near to neutral at the end of the experiment in all the treatments. Significant increase (p<0.05) in the electrical conductivity, total nitrogen (%), available phosphorus (mg 100g-1), available potassium (mg 100g-1) and a significant decrease (p<0.05) in total organic carbon (%) and C:N ratios from initial feed mixtures to final product in all the vermicomposting treatments were observed. The maximum rise in electrical conductivity, nitrogen, available phosphorus, and available potassium were recorded in the vermicompost obtained from Mikania-cowdung-mixtures. Interpretation: Vermicompost derived from Mikania-cowdung mixtures may be considered as suitable organic resource. Addition of carbonaceous materials such as leaf litters, sawdust, straw etc. with Mikania-cowdung mixtures is recommended for vermicomposting to increase the C:N ratio of vermicompost for slow release of nutrients.

Impact of age of rubber (Hevea brasiliensis) plantation on earthworm communities of West Tripura (India).

A comparative analysis of earthworm communities was carried out in the rubber plantations (Hevea brasiliensis) of different age groups in West Tripura to understand the impact of such exotic and monoculture plantation in biodiversity conservation. Earthworm communities were studied on monthly basis over a period of one year (2006-2007) in the 3, 10, 14, 20 and 25 year-old plantations. Among twelve earthworm species collected from the studied sites, six species belonged to Octochaetidae [Eutyphoeus assamensis Stephenson, Eutyphoeus comillahnus Michaelsen, Lennogaster chittagongensis (Stephensen), Octochaetona beatrix Gates, Dichogaster affinis Michaelsen, Lennogaster yeicus (Stephensen)], two species each to Megascolecidae [Metaphire houlleti (Perrier), Kanchuria sp. 1] and Moniligastridae [Drawida nepalensis Michaelsen, Drawida papillifer papillifer Stephenson], one species each to Glossoscolecidae [Pontoscolex corethrurus (Muller)] and Ocnerodrilidae [Gordiodrilus elegans Beddard]. Exotic species P. corethrurus, M. houlleti and native peregrine species like D. nepalensis and D. papillifer papillifer were distributed in all the age groups of plantation, while other species showed restricted distribution. P. corethrurus contributed more than 60% biomass and 70% density of earthworm communities in rubber plantation. With aging of rubber plantations both the densities and biomasses of earthworms increased. High contents of polyphenol, flavonoid and lignin in the litters of 3 and 10 year-old-rubber plantations through their effects on food intake, probably resulted to low biomass values of earthworms in those age groups of plantation. With further increase in the age of plantations beyond 10 years, polyphenol, flavonoid and lignin contents decreased. Accordingly the biomass of earthworms increased with increase in the age of plantation. Soil moisture increased with increase in the age of plantation and there was a good positive correlation between soil moisture and earthworm biomass (p<0.01). Density, biomass and dominance of earthworms increased while species diversity, species richness and species evenness of earthworm community were decreased with increase in the age of rubber plantation.

Effects of five earthworm species on some physico-chemical properties of soil.

An incubation experiment was conducted to study the changes that occur in organic carbon content, phosphorous and potassium availability and other soil properties with ingestion of soil mixed with rubber leaf litter and cow dung by five earthworm species viz. Pontoscolex corethrurus, Drawida assamensis, Drawida papillifer papillifer, Eutyphoeus comillahnus and Metaphire houlleti of rubber plantation in Tripura (India). Due to earthworm activity organic C (1.56-1.63%) and available P (14.71-27.60 mg 100 g-1) and K (43.50-49.0 mg 100 g-1) content of the soil increased significantly (p<0.05) in most of the earthworm species studied. M. houlleti and D. papillifer papillifer had the highest P (27.60 mg 100 g-1) and K (49.0 mg 100 g-1) mobilization capacity, respectively. Earthworms, irrespective of the species, increased the pH (7.05-7.17) and electrical conductivity (663-1383 µS cm-1) of the soil significantly (p<0.05).

Community structure of earthworms under rubber plantations and mixed forests in Tripura, India.

Studies on community structures of earthworms of rubber (Hevea brasiliensis) plantations and their adjacent mixed forests in West Tripura (India) revealed that both the studied sites harvoured 10 earthworm species. Nine species (Pontoscolex corethrurus, Kanchuria sp 1, Metaphire houlleti, Drawida papillifer papillifer, Drawida assamensis, Gordiodrilus elegans, Eutyphoeus assamensis, Eutyphoeus comillahnus and Eutyphoeus gigas) were common to both. While Octochaetona beatrix was found only in the rubber plantations, Dichogaster affinis was restricted to the mixed forest only. Earthworms were found mostly within 15 cm depth of soils having mean temperature of 27ºC, moisture of 23%, pH of 4.57, organic matter of 1.34% and water holding capacity of 36%. Mean earthworm density in rubber plantations (115 ind. m-2) was significantly higher (p = 0.003, t = 3.83) than that in the mixed forests (69 ind. m-2) due to dominance of Pontoscolex corethrurus, an exotic species. Numbers of dominant species were two (P. corethrurus and D. assamensis) in the rubber plantations and five (P. corethrurus D. assamensis, D. papillifer papillifer, M. houlleti and Kanchuria sp 1) in the mixed forests. Compared to the mixed forests, significantly low (p<0.05) Shannon diversity index (H) and species evenness and high index of dominance in the rubber plantation were evaluated.

Oxidant-antioxidant system: role and significance in human body.

Present article gives a holistic view of the causes, role and conrol of oxidative stress in the development and progression of various human diseases. Several types of reactive species are generated in the body as a result of metabolic reactions in the form of free radicals or non-radicals. These species may be either oxygen derived or nitrogen derived and called prooxidants. They attack macromolecules including protein, DNA and lipid etc. causing cellular/tissue damage. To counter their effect, the body is endowed with another category of compounds called antioxidants. These antioxidants are produced either endogenously or received from exogenous sources and include enzymes like superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, minerals like Se, Mn, Cu and Zn, and vitamins like vitamin A, C and E. Other compounds with antioxidant activity include glutathione, flavonoids, bilirubin and uric acid etc.. In a healthy body, prooxidants and antioxidants maintain a ratio and a shift in this ratio towards prooxidants gives rise to oxidative stress. This oxidative stress may be either mild or severe depending on the extent of shift and remains the cause of several diseases such as cardiovascular diseases, neurological diseases, malignancies, renal diseases, diabetes, inflammatory problems, skin diseases, aging, respiratory diseases, liver diseases and different types of viral infections. As more and more reports are pouring in, a lot of information is being unfolded about oxidative stress in relation to several other diseases.

Cocoon production, morphology, hatching pattern and fecundity in seven tropical earthworm species - a laboratory-based investigation.

Data on the reproductive biology of seven Indian species of earthworms, viz. Perionyx excavatus Perrier, Lampito mauritii Kinberg, Polypheretima elongata (Perrier), Pontoscolex corethrurus (Muller), Eutyphoeus gammiei (Beddard), Dichogaster modiglianii (Rosa) and Drawida nepalensis Michaelsen are presented. The peregrine earthworms such as Perionyx excavatus, Pontoscolex corethrurus, Dichogaster modiglianii, and Polypheretima elongata are considered to be continuous breeders with high fecundity. Native Lampito mauritii and Drawida nepalensis are semi-continuous and Eutyphoeus gammiei discrete breeders. There is a dramatic increase in cocoon production by most earthworm species of Tripura in the summer and monsoon with a corresponding peak during April and July. Cocoon production decreased or ceased during winter. Temperature affected the incubation period of cocoons. With increase in temperature, incubation period increased in the endogeic worms, Pontoscolex corethrurus, Polypheretima elongata and Drawida nepalensis and decreased in the epigeic worms, Perionyx excavatus and Dichogaster modiglianii, within a temperature range between 28-32 degrees C under laboratory conditions. There was a significant (P < 0.05) positive correlation between number of hatchlings per cocoon and incubation period in Lampito mauritii. High rate of cocoon production, short development time with high hatching success, as well as continuous breeding strategies in the epigeic species Perionyx excavatus and Dichogaster modiglianii and the top soil endogeic species, Pontoscolex corethrurus, Drawida nepalensis and Lampito mauritii, indicate their possible usefulness in vermiculture. The giant anecic worm, Eutyphoeus gammiei, which has a very long cocoon development time, discrete breeding strategy and very low rate of cocoon production, is not a suitable species for vermiculture.