E-Segments

Published Online in Agricultural Segment: 2(2) AGS/1558, 2011 : Enzyme Dynamics And Soil Properties In Paddy Soil Fertilized With Mineral And Green Manure N Sources

admin — Wed, 28 Dec 2011 12:51:05 +0000

Enzyme Dynamics And Soil Properties In Paddy Soil Fertilized With Mineral And Green Manure N Sources

Field experiments were conducted during kharif and rabi seasons of 2007 to study the influence of green manures and fertilizer nitrogen on enzyme dynamics and soil properties in lowland rice soil. The treatments consisted of N sources (prilled urea, Sesbania aculeata, Sesbania speciosa and Crotolaria juncea) and N levels (0, 50,100 and 150 kg ha^-1). The experiment was conducted in clay loam soil of Typic Haplustert having low organic carbon and nitrogen, medium in available P and high in available potassium. The test crop was rice var. ADT 43 (kharif) and ADT 38 (rabi). The results revealed that addition of green manures and fertilizer nitrogen recorded significant increase in enzyme activities (urease, dehydrogenase, phosphatase and amidase) throughout crop growth over control in both seasons. Green manure amended soil recorded higher enzyme activities over fertilizer nitrogen and Sesbania aculeata being dominant. All the enzyme activities increased consistently with N levels with urease and amidase being prominent. The highest enzyme activity was observed with 150 kg N ha^-1. The dehydrogenase, phosphatase and amidase activities increased up to flowering while urease increased up to tillering and then declined. All the enzymes showed significant and positive correlation with organic carbon, available N, P and K. Effect of enzyme activities was reflected in higher amount of available nutrients in soil in different treatments.

Authors: Sriramachandrasekharan M.V and M. Ravichandran

Published Online in Applied Science Segment: 1(2) APS/1531, 2010 : A Bidirectional Bayesian Monte Carlo Approach for Estimating Parameters of a Profile Hidden Markov Model

admin — Mon, 07 Mar 2011 19:22:32 +0000

A Bidirectional Bayesian Monte Carlo Approach for Estimating Parameters of a Profile Hidden Markov Model

Hidden Markov Models (HMMs) are statistical models frequently applied for modeling biological sequences. A Profile Hidden Markov Model (PHMM) is one of the applications of HMMs in bioinformatics. Estimating parameters of PHMM is one of the main challenges in applying them to real data in bioinformatics. In this paper, we give a brief review of two approaches named: the Baum-Welch algorithm and Bayesiyan Monte Carlo Markov Chain (BMCMC) method, for estimating parameters of PHMM. The common method for estimating parameters of HMMs usually considers the left side information of each observation. In order to improve the prediction accuracy of HMMs, in this paper we consider information on both sides of residues in a sequence for parameter estimation. The results show that using information on both sides of residues enables us to compare different methods for parameter estimation, more precisely. It is concluded that BMCMC method performs better than the Maximum Likelihood estimation. We also compare our results with those obtained when the Left-to-Right PHMM is applied.

Authors: Rosa Aghdam, Hamid Pezeshk^*, Seyed Amir Malekpour, Soudabeh Shemehsavar, Mehdi Sadeghiand Changiz Eslahchi

Published Online in Agricultural Segment: 1(2) AGS/1530, 2010 : Chemical composition and antifungal activity of the essential oil of Pulicaria arabica (L.) Cass. from Tunisia

admin — Wed, 09 Feb 2011 16:34:31 +0000

Chemical composition and antifungal activity of the essential oil of Pulicaria arabica (L.) Cass. from Tunisia

The chemical composition of the essential oils obtained by hydrodistillation from the parts of Pulicaria arabica (L.) Cass.growing in Tunisia and collected at full flowering stage were analysed by GC/MS. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds. The principal components of flowers essential oil were γ-cadinene (11.75 %), δ-cadinene (9.55 %); α-cadinol (8.59 %) while thymol (15.22 %), δ-cadinene (9.12 %), τ-cadinol (6.65 %) constituted the major components of stems essential oil. The roots were mainly composed of three constituents non identified, α-cadinol (2.9%) and thymol (2.45%). The essential oils were tested against Fusarium solani f.sp. cucurbitae, F. oxysporum f.sp. lycopersici, F. oxysporum f.sp. niveum, Phytophtora cactorum, Alternaria solani and Rhizoctonia solani. The results obtained show that the essential oils could be considered as natural fongicid agents.

Authors: Nadia El Abed*, Fethia Harzallah-Skhiri and Naima Boughalleb

Published Online in Biological Segment: 1(2) BS/1528, 2010 : Sub lethal effect of copper on bioaccumulation in the spiny lobster, Panulirus homarus, (Linnaeus,1758)

admin — Sat, 05 Feb 2011 07:38:08 +0000

Sub lethal effect of copper on bioaccumulation in the spiny lobster, Panulirus homarus, (Linnaeus,1758)

The spiny lobster Panulirus homarus were exposed to sublethal effects of copper and the accumulation of copper were analysed in muscle, hepatopancreas and gill tissues. The LC₅₀ 96hrs values 95.5µg/l in spiny lobster were estimated and various sublethal concentrations like 9.55µg/l and 19.1µg/l were selected. The accumulation of copper were observed in the sublethal concentrations on 7^th, 14^th,21^st and 28^th days of exposure. From the present study it is apparent that copper accumulation in P.homarus follows a pattern such as gills > hepatopancreas > muscle.

Author: Maharajan.A, Rajalakshmi,S, Vijayakumaran.M and Kumarasamy.P

Published Online in Agricultural Segment: 1(2) AGS/1525, 2010 : Water saving and eggplant response to subsurface drip irrigation

admin — Sat, 05 Feb 2011 07:32:12 +0000

Water saving and eggplant response to subsurface drip irrigation

New irrigation methods are being explored to find ways to save more water without losing the benefits of irrigation. Subsurface drip irrigation is a variation of the conventional surface drip irrigation. This study was conducted to evaluate the surface drip irrigation and subsurface drip irrigation’s application effects on eggplant crop performance at the Chott Mariem High Agronomic Institute, Sousse, Tunisia from February to June 2006. The observations were recorded on growth parameter, soil moisture content and yield of crop. Soil moisture measurements were taken up to 80 cm depth, using the Time Domain Reflectometry method. The experimental results indicated that the surface drip irrigation led to a greater yield making significant water saving 23.2% compared to surface drip irrigation. The study indicated that soil moisture content under subsurface drip irrigation was more uniform as compared with surface drip. It was found that plant height, yield and water use efficiency of eggplant increased due to subsurface laterals placement. The increased yield reached 40% compared to the surface drip (20 Kg/m² for drip irrigation and 28 Kg/m² for surface drip irrigation at 0.15 m depths of lateral placement) and the relative water stock`s variation is 46% compared to that surface drip.

Author: DOUH Boutheina* et BOUJELBEN Abdelhamid

Published Online in Agricultural Segment: 1(2) AGS/1523, 2010 : Rapid regeneration and efficient acclimatization of aromatic indica rice varieties

admin — Thu, 07 Oct 2010 18:02:46 +0000

Rapid regeneration and efficient acclimatization of aromatic indica rice varieties

Aromatic rice has a stronger aroma than ordinary rice and is very popular in South-East Asia. The present investigation was performed to optimize protocol for somatic embryogenesis and regeneration and to identify developmental stages of somatic embryos in different aromatic rice cultivars of rice. For all the cultivars hormone free MS medium was found suitable for callus proliferation as well as somatic embryogenesis. 0.5 mg l^-1 BAP in MS medium was found to be optimum is regeneration. MS medium (half strength) with 0.5 mg l^-1 NAA was found suitable for root induction. The globular and post globular stages of somatic embryos were found in microtome section cuttings. Well rooted plantlets from tissue culture medium were transferred to NFT (Nutrient Film Technique) for 4-6 weeks for proper root development.

Authors: Namita Singh, Alok Shukla and R.C. Pant

Published Online in Applied Science Segment: 1(2) APS/1522, 2010 : Synthesis of some substituted-1, 2, 4-triazole derivatives and investigation of their antimicrobial activities

admin — Thu, 07 Oct 2010 17:57:15 +0000

Synthesis of some substituted-1, 2, 4-triazole derivatives and investigation of their antimicrobial activities

The syntheses of a series of some sustituted-1, 2, 4-triazole derivatives are described. The reaction of sodium salt of α-sulphonated of stearic acid hydrazide (1) with carbon disulphide in alcoholic KOH yielded the corresponding sodium 1-(4-amino-5-mercapto-4H-[1, 2, 4]-triazol-3yl) heptadecane-1-sulfonate (2). The reaction of compound (2) with carbon disulphide in pyridine, acid chlorides and appropriate aldehydes yielded the substituted 1,2,4-triazole derivatives (3), (4) and (5) respectively. All the synthesized compounds were characterized by IR, PMR, Mass spectral data and elemental analyses. All newly synthesized compounds have been assayed for their antibacterial activity against S. aureus, E. coli, B. subtilis and P. aeruginosa.

Author: Ram Janam Singh

Published Online in Agricultural Segment: 1(2) AGS/1521, 2010 : Zinc efficiency, Zinc concentration of Maize cultivars grown in a zinc-deficient calcareous soil

admin — Thu, 07 Oct 2010 17:52:31 +0000

Zinc efficiency, Zinc concentration of Maize cultivars grown in a zinc-deficient calcareous soil

Four cultivars of Maize (301 Single Grass (A), 302 Single Grass (B), 307 Single Grass (C), 400 Single Grass (D), Zea mays L.) were used to study the influence of varied zinc (Zn) supply on Zn efficiency, and on shoot dry weight and Zn concentration. Plants were grown in a Zn-deficient calcareous soil under greenhouse conditions with (+Zn = 10 mg kg soil) and without (-Zn) Zn supply. plants were harvested after 40 and 80 days. Zinc efficiency, expressed as the percentage of shoot dry weight produced under conditions of Zn deficiency compared to Zn supply, ranged between 62.3% and 75.5% in first stage and between 63.5% and 81.2% in second stage. application of Zinc caused increase in shoot dry weight in all cultivars. After 40 day, highest and lowest amount of Zn concentration in shoot were in D and A cultivars respectively and in second stage maximum concentration of Zinc was in D cultivar which has highest Zn efficiency. Zn concentration in shoot was related to Zn efficiency. Zn efficiency correlated with Zn concentration in shoot of different cultivars.

Authors: A. Chaab, Gh. Savaghebi and B. Motesharezadeh

Published Online in Agricultural Segment: 1(1) AGS/1520, 2010 : Comparative growth of weedy rice and rice in Asia

admin — Sun, 26 Sep 2010 13:34:17 +0000

Comparative growth of weedy rice and rice in Asia

A study was conducted in a screenhouse to characterize the competitive abilities of weedy rice (WR) populations from five Asian countries [India (IWR), Malaysia (MWR), Philippines (PWR), Thailand (TWR), and Vietnam (VWR)] grown together with rice (cv. IR64, a widely grown variety in Asia). Rice and each weedy rice population were grown in a replacement series design at proportions of 0:100, 25:75, 50:50, 75:25, and 100:0. Response curves were used as an indicator of the extent of competition between IR64 and weedy rice. TWR was equally competitive to IR64 in terms of producing number of tillers, and leaf area. Conversely, other four weedy rice populations were more competitive than IR64. Relative yield of IR64 based on the shoot biomass was lower than that of IWR, MWR, PWR, or VWR, whereas it was comparable to that of TWR. Rice plants had similar height to TWR plants, but were shorter than the plants of other four weedy rice populations. The results from this study demonstrate that weedy rice populations have varying response to competition with cultivated rice (IR64). Multiple approaches, including varietal and agronomic practices, need to be exploited in Asia as a component of integrated weed management in weedy rice control.

Authors: Bhagirath S. Chauhan and David E. Johnson

Published Online in Applied Science Segment: 1(1) APS/1519, 2010 : Magneto Hydrodynamic Transient Natural Convective Flow past a surface embedded in Porous Medium due to combined effects of Thermal and Mass Diffusion

admin — Sun, 26 Sep 2010 13:29:23 +0000

Magneto Hydrodynamic Transient Natural Convective Flow past a surface embedded in Porous Medium due to combined effects of Thermal and Mass Diffusion

This paper presents an analysis of combined heat and mass transfer flow past an oscillating vertical plate under the action of transverse applied magnetic field taking into account the periodic temperature variation of the plate when the plate is embedded in porous medium. The governing equations are solved in closed form by Laplace-transform technique. The results are obtained for temperature, velocity, penetration, Nusselt number and skin-friction. The effects of various parameters on flow variables are illustrated graphically and the physical aspects of the problem are discussed.

Author: Dr. Arpita Jain