Growing areas under transgenic crops have created a concern over their possible adverse impact on the soil ecosystem. This study evaluated the effect of Bt-cotton based cropping systems on soil microbial and biochemical activities and their functional relationships with active soil carbon pools in Vertisols of central India (Nagpur, Maharastra, during 2012–2013). Culturable groups of soil microflora, enzymatic activities and active pools of soil carbon were measured under different Bt-cotton based cropping systems (e.g. cotton-soybean, cotton-redgram, cotton-wheat, cotton-vegetables and cotton-fallow). Significantly higher counts of soil heterotrophs (5.7–7.9 log cfu g?1 soil), aerobic N-fixer (3.9–5.4 log cfu g?1 soil) and P-solubilizer (2.5?3.0 log cfu g?1 soil) were recorded in Bt-cotton soils. Similarly, soil enzymatic activities, viz. dehydrogenase (16.6–22.67 µg TPF g?1 h?1), alkaline phosphatase (240–253 µg PNP g?1 h?1) and fluorescein di-acetate hydrolysis (14.6–18.0 µg fluorescein g?1 h?1), were significantly higher under Bt-cotton-soybean system than other Bt- and non-Bt-cotton based systems in all crop growth stages. The growth stage-wise order of soil microbiological activities were: boll development > harvest > vegetative stage. Significant correlations were observed between microbiological activities and active carbon pools in the rhizosphere soil. The findings indicated no adverse effect of Bt-cotton on soil biological properties. 相似文献
Nandus nandus is a threatened fish species that plays a significant role in the nutrition of India, especially in the Northeastern states. In the present study, induced spawning of a threatened freshwater fish Nandus nandus (Hamilton-Buchanan) was conducted using three commercially available synthetic GnRH preparations viz., wova- FH, ovaprim, and ovatide in different intensities. The brooder females were injected one time and left to spawn in the spawning hapa. It was found that at different dosages (0.1 ml, 0.2, and 0.3 ml/kg of body weight) hormone wova-FH and ovaprim could induce the fishes to spawn. No spawning was observed by females treated with ovatide and in control set. The spawning time, fertilization rate, hatching rate, and survival rate were quantified in each set of experiment. The egg output/gm female was higher with the dosage of 0.3 ml in comparison to 0.1 ml/kg and 0.2 ml/kg of body weight of ovaprim and wova-FH. The statistical analysis showed significant effect (P < 0.05) between hormonal doses with latency period, fertilization rate, incubation period, hatching percentage, and egg output. The present study suggests that wova –FH and ovaprim at 0.3 ml/kg body weight of fish are more effective in induction of spawning of N. nandus. 相似文献
Mercury (Hg) is an environmental pollutant which is detrimental to the health of living beings due to the toxicity in its all oxidation states. To control mercury pollution development of low cost, efficient and highly sensitive prototype mercury sensor remains a challenge. In the present work, we have proposed a low-cost prototype device based on silver nanoparticle-impregnated poly(vinyle alcohol) (PVA-Ag-NPs) nanocomposite thin film for mercury detection. The thin film, fabricated through a facile protocol, is shown to be a fast, efficient, and selective sensor for Hg2+ in aqueous medium with a detection limit of 10 ppb. We have utilized the aggregation and amalgamation of Ag-NPs with Hg2+ to develop the low-cost, highly efficient and feasible prototype mercury sensor. In the presence of Hg2+, the yellowish thin film turned into colourless due to the loss of intense surface plasmon resonance (SPR) absorption band of the silver nanoparticles (Ag-NPs) through aggregation and amalgamation with mercury. The developed sensor has high selectivity for Hg2+ ions over a wide range of other competing heavy metal ions, generally present in water of natural sources. The sensor response is found to be linear over the Hg2+ ion concentration regime from 10 ppb to 5 ppm. The developed sensor has shown to determine a trace Hg2+ ions in real water samples. Finally, using the proposed technique, we have developed a simple and inexpensive prototype device for monitoring in field environmental mercury pollution.
The temporal changes of nutrient concentration in leaves and their accumulation in fruit are good indicators of plant nutrient demand for each developmental stage. Seasonality of nutrients in leaves and fruits of pomegranate and their relation with fruit quality was evaluated in commercial orchards using cv. “Bhagwa.” The concentration of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), iron (Fe), zinc (Zn) and boron (B) in leaves decreased while calcium (Ca), magnesium (Mg), manganese (Mn) and copper (Cu) concentration increased during fruit growth and development. Total nutrient accumulation increased gradually in fruit and translated into growth of arils, and increase in juice content and total soluble solids, however as the biomass accumulation in fruit was much faster than nutrient accumulation, concentration of majority nutrients except Mg decreased rapidly, followed by slow and continuous decrease till maturity. During fruit enlargement, demand for N, P, K, Fe, Cu and Zn was high while requirement for Ca, Mg and S was high during fruit development. 相似文献
Huge depletion of soil microflora under conventional farming practice has become the primary contributory factor toward the present depletion of soil and crop productivity. Reconstitution of soil microbial dynamics has been identified as the only way out, but there has been a debate regarding the most effective pathway for soil rejuvenation i.e. whether to create the environment for natural proliferation or opt for inoculation of laboratory generated microbes. In this respect, a study was undertaken at Maud T.E. (Assam) under FAO-CFC-TBI Project, where bio-fertilizer (microbial inoculant, MI), vermicompost (organic food source, OF), vermicompost + bio-fertilizer (OF+MI), and Novcom compost (representing self-generated native microflora in the order of 1016c.f.u. along with organic food source, SNM); were taken as treatments for a yield target of 1500 kg made tea/ha. The highest crop yield (1500 kg ha?1) along with high and consistent soil quality development was noted under SNM treatment; while MI influenced lowest yield (1268 kg ha?1) and minimal soil response. Addition of the organic food source with cultured microbes (MI+OF) was found to improve crop performance (1427 kg ha?1), but with 7.60 times higher cost (Rs. 39.97 kg?1 made tea). Economic viability study indicated that except SNM, all other treatments were vulnerable toward crop loss or market downfall. 相似文献
The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, ?151 to ?37 mV; mean, ?68 mV) and nitrate (range, 0.01–1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100–630 mg/l; mean, 301 mg/l), Fe (range, 0.99–38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01–15 mg/l; mean, 0.54 mg/l), hardness (range, 46–600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19–88 mg/l; mean, 7.2 mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269 μg/l) and Fe (mean, 9.8 mg/l). Questionnaire survey highlights that ～70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated. 相似文献
Estimation of available‐boron (B) status through conventional methods in B‐deficient acidic Inceptisols and Entisols is often hampered because of their very low B content. In the present study, the extractability of available B by different extractants was tested in relation to soil properties. Plant availability of B was assessed with mustard (Brassica campestris L.) and wheat (Triticum aestivum L.) in pot experiments. Twelve soils with varying characteristics were extracted for available B with hot water (HW), hot CaCl2 (HCC), KH2PO4 (PDP), tartaric acid (TA), and mannitol‐CaCl2 (MCC). Mustard (cv. B‐9) and wheat (cv. PBW‐343) were grown with four levels of B (0, 0.25, 0.50, and 1.0 mg [kg soil]–1). Dry‐matter accumulation and B concentrations were determined at pre‐flowering and full‐maturity stages for mustard and at panicle‐initiation and maturity stages for wheat. The extraction of B from the soils ranked HCC > HW > PDP > TA > MCC. The higher extractability with HW and HCC was likely due to higher temperature and that of PDP because of its phosphorus content, which facilitated the desorption of B. The low B extraction with MCC resulted from the poor mannitol‐B complex formation in acidic soils. The application of B increased dry‐matter accumulation, plant B concentration, and uptake at all B levels and growth stages in both crops with the responses being more pronounced during the early developmental stage. Based on linear correlations, Mallow's Cp statistics, and principal‐component analyses, HCC and HW were the best extractants for estimating available B in the acidic experimental soils. 相似文献
Sarkar et al. (this issue) proposed a laboratory measurement method for obtaining the hydraulic conductivity of soil at near‐saturated moisture conditions, bridging the gap between measurements that can be obtained with the evaporation method in the medium dry region, and measurements of the saturated conductivity by traditional methods. The method is based on a tension infiltration on a limited part of the surface of a soil sample and drainage of the sample at the same tension, leading to a divergent flow field. Despite equal tensions at top and bottom of the sample (“unit gradient”), the water flux in the sample is smaller than the corresponding value of the soil hydraulic conductivity at the applied tension. From numerical analysis of the flow problem, they concluded that unsaturated conductivity can be obtained with an accuracy of 10% for all texture classes of the USDA soil texture triangle. In this paper, we test the methodology for three different soil types using an appropriate apparatus. The results match well with independent saturated conductivity measurements on the wet side, and with unsaturated conductivity measurements in the medium moisture range that were obtained with the evaporation method. 相似文献
Accurate and reliable predictive models are necessary to estimate above and below ground biomass of plant and biomass carbon stock non-destructively. Different growth models namely viz, Linear, Allometric, Logistic, Gompertz, Richard’s, Negative exponential, Monomolecular, Mitcherlich and Weibull were fitted to the relationship between dry biomass of litchi tree components with collar diameter. Richard’s model outperformed the others and fulfilled the validation criterions to the best possible extent with lowest Akaike information criteria (AICc) of 90.47 and root mean square error (RMSE) of 1.79. The value of adjusted R2 ranged from 0.947 to 0.971 for the Richard’s models fitted on various biomass components and the ‘t’ values for all the components was found non-significant (p > 0.05) indicating the validation of the model. The estimated total dry biomass varied from 0.50 Mg ha?1 in two year to 5.71 Mg ha?1 in 10 year old litchi orchards. The estimated stored biomass carbon stock in litchi orchards (branches, bole and roots) varied from 0.10 Mg ha?1 in two year to 1.85 Mg ha?1 in 10 year orchards with CO2 sequestration potential from 0.19–4.63 Mg ha?1. 相似文献
Efficient estimation of soil organic carbon (SOC) is vital for understanding and monitoring the effect of perennial fodder crops in conserving SOC. In subtropical regions, there is limited information on SOC accumulation and its allocation into different pools under long‐term grasses and legumes. Therefore, we investigated the dynamics of SOC in a 20‐year‐old field trial with seven perennial grass species and a legume in a Typic Paleudalf soil under subtropical climate in north‐east India by analysing oxidizable organic C (Coc) and its fractions of very labile (CVL), labile (CL), less labile (CLL) and non‐labile (CNL), microbial biomass C (Cmic) and mineralizable C (Cmin). Growing perennial fodder crops increased SOC in the 0–0.60 m soil depth from 19.9%–39.6% compared with the conventional cultivation with maize (Zea mays). The relative efficacy of the fodder species to SOC accumulation was Setaria sphacelata = Brachieria rosenesis > Panicum maximum cv. Makunia = Arachis pintoi > Panicum maximum cv. Hamil > Paspalam conjugalum = Pennisetum purpureum > Thysanolaena maxima. Among the analysed fractions, CVL, CL, CLL and Cmic were influenced most by the fodder crops and the active pools (CVL+CL) constituted 71.6% of the SOC. The results indicate that under the tested subtropical climate, soil under perennial grasses and legumes conserves organic C and that most of the SOC is in labile pools of short residence time. 相似文献
下载免费PDF全文