Purpose Rubber leaves are the abundant agro-waste and pineapple, the most economically important fruit crop in Tripura. So, in our present study, different amounts of rubber leaf vermicompost have been applied to the soils of pineapple plantation to determine their effects on earthworms-the soil ecosystem engineers, coupled with the vegetative growth and yield of pineapples. Methods During 30 months of field trial (2010-2012) in ICAR regional station, Lembucherra, West Tripura, the control plot (T 0 ) received no fertilizer, while experimental plots were fertilized with four different amounts of vermicompost viz. T 1 (5 tons ha -1 year -1 ), T 2 (10 tons ha -1 year -1 ), T 3 (20 tons ha -1 year -1 ) and T 4 (30 tons ha -1 year -1 ). Results A significant (p \ 0.05) but gradual increase in density (up to T 3 treatment) and biomass (up to T 4 treatment) of earthworms were recorded with the increasing amounts of vermicompost. During the second year, average length and width of leaves, number of leaves per plant, plant girth, fruit weight, fruit yield and fruiting percentage were highest in the T 3 plot compared to other treated plots and control. ConclusionThe present study reveals that crop yield is very much related to the particular concentration of vermicompost, beyond the level of which production declines and increase in vegetative growth, fruit weight and fruiting percentage of pineapple are strongly linked with the soil pH, av. P, av. K, clay content and the earthworm density of soils.

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The impact that plant communities may have on underground faunal diversity is unclear. Therefore, understanding the links between plants and organisms is of major interest. Earthworm population dynamics were studied in the pineapple agroecosystems of Tripura to evaluate the impact of monoculture plantation on earthworm communities. A total of thirteen earthworm species belonging to four families and five genera were collected from different sampling sites. Application of sample-based rarefaction curve and nonparametric richness estimators reveal 90–95% completeness of sampling. Earthworm community of pineapple agroecosystems was dominated by endogeic earthworms andDrawida assamensiswas the dominant species with respect to its density, biomass, and relative abundance. Vertical distribution of earthworms was greatly influenced by seasonal variations. Population density and biomass of earthworms peaked during monsoon and postmonsoon period, respectively. Overall density and biomass of earthworms were in increasing trend with an increase in plantation age and were highest in the 30–35-year-old plantation. Significant decrease in the Shannon diversity and evenness index and increase in Simpson’s dominance and spatial aggregation index with an increase in the age of pineapple plantation were recorded. Soil temperature and soil moisture were identified as the most potent regulators of earthworm distribution in the pineapple plantation.

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The present investigation has been conducted to assess the AMF (Arbusculr Mycorrhiza Fungi) colonization status along with rhizosphere soil properties of dominant plants and grass species in Rajshahi BCSIR forest of Bangladesh. Roots of six dominant plants (Psidium guajava, Swietenia mahagoni, Artocarpus heterophyllus, Manihot esculenta, Acalypha indica, Fragaria ananassa) and two grass species (Digitaria sanguinalis, Cynodon dactylon) were collected and rhizosphere soil samples were collected from rhizosphere zone. Mycorrhizal colonization percentages and edaphic factors (Soil pH, EC, N, P, Moisture and Soil Temperature) were documented. Highest colonization was obtained in Manihot esculenta (85±5%) followed by Swietenia mahagoni (78±10.36%) and lowest was observed in Acalypha indica (2±1.9%). Mycorrhizal structure as arbuscles, vesicles were present in Psidium guajava, Swietenia mahagoni, Manihot esculenta among the studied species. Research findings indicate that plants species of Rajshahi BCSIR forest is mycorrhizal but not well established as well as mycorrhizal infection is irregularly correlated with edaphic factors.