Site-specific nutrient requirements of NPK for potato (Solanum tuberosum L.) in Western Indo-gangetic plains of India based on QUEFTS

Abstract

Potato productivity in India is static due to unbalanced use of nutrients and intensive cropping system. Nutrient use efficiency and yield can be increased by application of nutrients based on quantitative approaches. We calibrated the quantitative evaluation of fertility of tropical soils (QUEFTS) model for the estimation of NPK requirements for different targeted yields of potato. Published data sets were used to calibrate the model. The results of the study showed that to produce one ton of potato tubers, 18, 4, and 24?kg N, P, and K, respectively, would be needed with internal efficiencies of 55, 285, and 42?kg tuber dry yield/kg N, P, and K removed. The observed yields of potato with different amount of nutrients were in agreement with the values predicted by the model. Therefore, the QUEFTS model based NPK fertilizer recommendations can be adopted for site-specific nutrient management of potato.     

Effects of microbial inoculations on soil chemical,biochemical and microbial biomass carbon of cassava (Manihot esculenta Crantz) growing Vertisols

Cassava is an important subsidiary food in the tropics. In Tamil Nadu, India, microbial cultures were used to eradicate the tuberous root rot of cassava. Hence, an experiment was conducted for two consecutive years to test the effects of coinoculation of microbes on soil properties. The surface soil from the experimental site was analysed for soil available nutrients, soil enzyme activities and microbial biomass carbon. The treatment of Azospirillum with Trichoderma at the 50% recommended N:P₂O₅:K₂O (NPK) rate (50:25:50 kg ha^?1) significantly increased soil available nitrogen (142.81 kg ha^?1) by 72.66% over uninoculated control. There was a significant increase in available phosphorus in soil by the inoculation of AM (arbuscular mycorrhizal) fungi with Trichoderma at the 50% recommended NPK rate (41.04 kg ha^?1) compared to other treatments. The application of Pseudomonas fluorescens with Trichoderma at the 50% recommended NPK rate significantly increased available iron (19.34 µg g^?1) in soil. The treatment of Azospirillum with Trichoderma increased urease enzyme activity at the recommended NPK rate (816.32 μg urea hydrolyzed g^?1 soil h^?1). Soil application of all cultures at the 50% recommended NPK rate significantly increased dehydrogenase activity (88.63 μg TPF g^?1 soil) and β-glucosidase activity (48.82 μg PNP g^?1 soil) in soil. Inoculation of Trichoderma alone at the 50% recommended NPK rate significantly increased microbial biomass carbon (3748.85 μg g^?1 soil). Thus, the microbial inoculations significantly increased soil available nutrient contents, enzyme activities such as urease, dehydrogenase and β-glucosidase activity and microbial biomass carbon by reducing the amount of the required fertilizer.     

Quantitative determination of NPK uptake requirements of taro (Colocasia esculenta (L.) Schott)

Taro yield in many parts of the world is stagnant mainly due to conventional blanket recommendation of fertilizers, lower nutrient use efficiency and imbalance in the use of nutrients. The Quantitative Evaluation of Fertility of Tropical Soils (QUEFTS) model was used for determining the region specific balanced NPK uptake requirements and recommendations for a target yield of taro. The constants for minimum and maximum accumulation (kg cormel kg^?1 nutrient) of N (33 and 177), P (212 and 606) and K (25 and 127) were derived as standard model parameters. The results showed that taro requires N, P and K accumulation of 12.97, 2.75 and 17.47?kg t^?1 of cormel yield, suggesting an average NPK ratio in the plant dry matter of about 4.7:1:6.4. The NPK fertilizer requirements for different potential yield situations were also calculated. The results need to be validated in major taro growing regions.     

Assessment of hydrogeochemical characteristics of groundwater in shrimp farming areas in coastal Tamil Nadu, India

Brackishwater aquaculture is basically farming in coastal region, and it utilizes the saline water from either sea or estuary or creek. Assessment of hydrogeochemisty of groundwater resources in shrimp farming areas is very much required not only for monitoring the shrimp farming impacts, but also to suggest better management strategies for the long-term sustainability of shrimp farming and integrated water resources management in coastal regions. Watershed-based assessment is ideal as watershed is a geohydrological unit, and it will give the realistic and cumulative effects more precisely. With this background, the present investigation was carried out to evaluate the geochemical process regulating groundwater quality in shrimp farming areas of coastal miniwatersheds of Vellar and Coleroon river, Cuddalore district, Tamil Nadu, along the east coast of India. Representative groundwater (29) samples from shallow aquifer (hand pump and open well) were collected periodically (June 2008, January 2009, April 2009 and July 2009) using the simple random sampling method and analyzed for various water quality parameters viz. pH, TDS, total hardness, alkalinity, cations (Ca⁺, Mg⁺, Na⁺) and anions (Cl^?, SO₄ ^?, NO₃ ^?, HCO₃ ^?). The groundwater data indicated that the HCO₃ was the dominant ion in the study area with sodium (Na > Ca > Mg) and bicarbonate (HCO₃ > Cl > SO₄) as the predominant cation and anion, respectively. The large variations in mean and standard deviation of ionic concentration suggest that the water chemistry in the study region was not homogenous and may be influenced by complex sources for the hydrogeochemical processes. The piper trilinear diagram depicts the status of the groundwater quality and also suggests that the cation exchange and mineral dissolution was responsible for this elevated ionic composition at some locations in the study area. The multivariate statistical analysis viz., principal component analysis and cluster analysis clearly elucidated that the groundwater quality in the area is mainly due to natural process and the shrimp farming is not an influencing factor.     

Differential response of short‐ and long‐duration cassava cultivars to applied mineral nitrogen

The differential response of two contrasting cassava cultivars to different rates of soil‐applied nitrogen (N) on the number of tuberous roots, harvest index, yield, nitrogen uptake, and fertilizer‐nitrogen‐use efficiency was studied over a period of 2 years on a typic Plinthustults in Kerala state in Southern India. The experiment was laid out in a split‐plot design with two popular cultivars of cassava, namely Sree Vijaya (6 months) and M‐4 (10 months) in the main plots, and eight urea‐N rates (0, 12.5, 25, 50, 75, 100, 150, and 200 kg ha^–1) in subplots. Half of the N was applied at the time of planting and the other half 60 d later. The study revealed significant differences between the two cultivars regarding their response to fertilizer‐N application. The tuberous‐root yield of the short‐duration cultivar Sree Vijaya increased significantly up to 100 kg N ha^–1 whereas the yield of the long‐duration cultivar M‐4 increased significantly only up to 50 kg N ha^–1 rate. Also the N‐use‐efficiency parameters (i.e., agronomic, recovery, and physiological efficiencies) were higher in Sree Vijaya than in M‐4 but declined at N rates beyond 100 kg ha^–1. The more efficient N use in the short‐duration cultivar was associated with a higher N uptake and a more efficient internal use.     

Empirical feed formulations for the marine ornamental fish,striped damsel,Dascyllus aruanus (Linné 1758) and their physical,chemical and nutritional evaluation

Formulated feeds containing a common ingredient mixture (CIM) consisting of fishmeal (anchovies), shrimp meal (Acetes), squid meal (Loligo) and soybean meal incorporated in ascending levels to obtain protein levels ranging from 180 to 560 g kg^?1(18.34%, 25.35%, 36.27%, 46.61% and 56.28%) and an energy level of 19 MJ kg^?1 were fed to the marine ornamental fish, striped damsel, Dascyllus aruanus <200 mg and 200–300 mg in size for periods of 35 and 63 days. The <200 mg fish accepted particles <0.5 mm in size and showed maximum growth in terms of absolute growth rate (AGR), relative growth rate (RGR) and specific growth rate (SGR) with the feed containing 380 g kg^?1 CIM having a protein content of 362 g kg^?1. Second‐degree polynomial regression equations fitted confirmed these observations with a predicted requirement of 360 g kg^?1 protein. In fish weighing 200–300 mg, growth was not significantly different (P>0.05) in fish fed with feeds containing 380 and 580 g kg^?1 CIM with 360 and 470 g kg^?1 protein. With these data, the second‐degree polynomial regressions showed that a protein level of 464 g kg^?1 would result in an RGR of 107%. The feeds were well accepted by the damselfish, showing good colour retention and health.The cost of the feeds excluding processing costs ranges from US $ 1.35 to 3.36 kg^?1. This is the first report on the development of formulated feeds for damselfish that would help in rearing and aquarium keeping of damselfish worldwide.     

Evaluation of Biochemical and Nutritional Potential of Seaweeds from Lakshadweep Archipelago

The variation of the proximate composition and mineral content of nine seaweeds available in the Lakshadweep group of islands were studied to evaluate their nutritional quality. The proximate composition and the mineral contents were determined as per standard methodologies. The nutritional quality was found to be comparable with common vegetables and fruits. Hansen’s nutritional quality index has shown the seaweeds U. lactuca, H. valentea, and H. muciformis, in particular, to be safe for their versatile use and that they can contribute to a healthy balanced diet.     

Prevalence of zoonotic important parasites in the red fox (Vulpes vulpes) in Great Britain

A national necropsy survey of red foxes was carried out across Great Britain to record Echinococcus, Trichinella and Toxoplasma. The survey did not record directly, or indirectly using coproantigen/PCR tests, evidence for the presence of Echinococcus multilocularis in 588 animals, although E. granulosus was suspected in six animals. Parasitological evidence for Trichinella spp. could not be found in 587 fox muscle digests, and a specific PCR test also failed to detect Toxoplasma in a sub-set of 61 random fox tongue biopsies. The upper 95% confidence interval for the above parasites was 0.60% (E. multilocularis), 0.60% (Trichinella spp.) and 5.6% (Toxoplasma). The commonest gut parasites were the hookworm Uncinaria stenocephala (41.3%) and the ascarid Toxocara canis (61.6%). This study also reports the second occurrence of Trichuris vulpis in Great Britain.     

The role of WC1(+) gamma delta T-cells in the delayed-type hypersensitivity (DTH) skin-test reaction of Mycobacterium bovis-infected cattle

Delayed-type hypersensitivity (DTH) skin-testing with mycobacterial antigens is often used as a means of identifying Mycobacterium bovis-infected cattle. Better understanding of the cellular basis underlying the DTH reaction is required if diagnostic methods are to be improved upon. Previous studies have shown that gamma delta T-cells, particularly those bearing the WC1 molecule, are present at an early stage of developing DTH responses and that such cells may modulate the developing immune response immediately following M. bovis-infection. However, their role, if any, in the DTH response remains unclear. In the present study we have used an in vivo model to deplete WC1(+) gamma delta T-cells, from cattle with established M. bovis-infection, prior to skin-testing. Results indicate that, although WC1(+) gamma delta T-cells do infiltrate the skin-test site in normal calves, they do not appear to be essential for the development of DTH skin swelling, as indicated by effective development of skin responses in calves depleted of circulating WC1(+) gamma delta T-cells.