Wyniki wyszukiwania - Biblioteka Nauki

1

Salinity and its effects on the functional biology of legumes

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Manchanda G. , Garg N.

Acta Physiologiae Plantarum

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2008

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tom 30

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nr 5

EN

Salinity has plagued soil fertility and drastically affected growth and survival of glycophytes in irrigated regions of the world since the beginning of recorded history. It is particularly common in arid and semi-arid areas where evapotranspiration exceeds annual precipitation, and where irrigation is therefore necessary to meet crop water needs. Salt buildup in the soils and groundwater has threatened its productivity and sustainability. Plant responses to salt stress include an array of changes at the molecular, biochemical and physiological levels. Salt stress involves a water deficit induced by the salt concentration in the rhizosphere, resulting in disruption of homeostasis and ion distribution in the cell and denaturation of structural and functional proteins. As a consequence, salinity stress often activates cell signaling pathways including those that lead to synthesis of osmotically active metabolites, specific proteins, and certain free radical scavenging enzymes that control ion and water flux and support scavenging of oxygen radicals or chaperones. ROS detoxification forms an important defense against salt stress. Legumes are a key component of sustainable agriculture and can offer many economic and environmental benefits if grown more widely in crop rotations because of their ability to fix nitrogen in the root nodules in a symbiotic interaction with soil rhizobia. Due to their capacity to grow on nitrogen-poor soils, they can be efficiently used for improving saline soil fertility and help to reintroduce agriculture to these lands. However, in legumes, salt stress imposes a significant limitation of productivity related to the adverse effects on the growth of the host plant, the rootnodule bacteria, symbiotic development and finally the nitrogen fixation capacity. This paper reviews responses of legumes to salinity stress with emphasis on physiological and biochemical mechanisms of salt tolerance.

2

Influence of zinc on cadmium-induced toxicity in nodules of pigeonpea (Cajanus cajan L. Millsp.) inoculated with arbuscular mycorrhizal (AM) fungi

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Garg N. , Kaur H.

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2012

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tom 34

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nr 4

EN

Arbuscular mycorrhizal (AM) fungi are known to alleviate heavy-metal stress in plants. The intent of the present work was to analyze accumulation of heavy metals (Cd and Zn) in nodules of two Cajanus cajan (L.) Millsp. genotypes and their subsequent impact on nitrogen fixation, oxidative stress, and non-protein thiols (glutathione and phytochelatins) with and without AM fungus Glomus mosseae. Accumulation of Cd and Zn in nodules resulted in sharp reduction in nodule number, nodule dry mass as well as nitrogen fixation (leghemoglobin and nitrogenase (N₂ase)), although Cd had more pronounced effects than Zn. Cd-induced lipid peroxidation, H₂O₂ accumulation, and electrolyte leakage were largely reversed by Zn supplementation. Zn application significantly altered the negative effects of Cd on the synthesis of non-protein thiols, suggesting antagonistic behaviour of Zn. Higher concentration of Zn was more effective in lessening the negative effects of Cd than its lower concentration. Remarkable genotypic variation was found, with more severe effects of both the metals in P792 than Sel 85N. Glomus mosseae attenuated the phytotoxic effects of metals in nodules by decreasing metal uptake, oxidative stress, and by enhancing defense system ultimately leading to better nitrogen-fixing potential of pigeonpea nodules.

3

Prediction of Sound Insulation of Sandwich Partition Panels by Means of Artificial Neural Networks

80%

Garg N. , Dhruw S. , Gandhi L.

Archives of Acoustics

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2017

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tom Vol. 42, No. 4

643--651

EN

The paper presents the application of Artificial Neural Networks (ANN) in predicting sound insulation through multi-layered sandwich gypsum partition panels. The objective of the work is to develop an Artificial Neural Network (ANN) model to estimate the Rw and STC value of sandwich gypsum constructions. The experimental results reported by National Research Council, Canada for Gypsum board walls (Halliwell et al., 1998) were utilized to develop the model. A multilayer feed-forward approach comprising of 13 input parameters was developed for predicting the Rw and STC value of sandwich gypsum constructions. The Levenberg-Marquardt optimization technique has been used to update the weights in back-propagation algorithm. The presented approach could be very useful for design and optimization of acoustic performance of new sandwich partition panels providing higher sound insulation. The developed ANN model shows a prediction error of ± 3 dB or points with a confidence level higher than 95%.

4

Analysis of emergence stage facilitates the evaluation of chickpea (Cicer arietinum L.) genotypes for salinity tolerance imparted by mycorrhizal colonization

80%

Garg N. , Manchanda G. , Singla P.

Acta Physiologiae Plantarum

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2014

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tom 36

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nr 10

EN

Salinity is an ever-increasing constraint limiting crop production in arid and semi-arid regions. Arbuscular mycorrhiza (AM) helps host plant to cope with detrimental effects of salinity. Experiments were aimed to examine the hypothesis that emergence is a better stage to determine salt tolerance of chickpea genotypes than germination and genotypic variability in their tolerance ability at emergence and subsequent vegetative growth is the manifestation of differential benefits imparted by mycorrhiza. Investigations were carried out at germination and emergence stage of genotypes (PBG 5, GPF 2, PBG 1, BG 1053, L 550) at 0, 40, 60, 80 mM NaCl. Significant genotypic variations in salt tolerance were observed at emergence rather than germination because of greater inhibitory effects on seedling emergence. Percent mycorrhizal colonization (MC) and its resulting impact on respiration rate (RR) and salt tolerance index (STI) at emergence indicated that PBG 5, with lowest RR, highest STI and mycorrhiza benefit percentage was the most tolerant whereas, L 550 the most sensitive genotype. Genotypic variability recorded at 30 days was consistent with that at emergence stage. Superior salt tolerance of PBG 5 than L 550 could be attributed to higher correlation between MC and physio-biochemical traits (RWC, chlorophyll a/b, proline accumulation, antioxidant activities). The study supported the hypothesis that both emergence stage and mycorrhizal effectiveness are important determinants of salt tolerance in chickpea genotypes. Evaluation of genotypes for relative adaptation to salinity should include estimation of their differential salt tolerance at different growth stages and symbiotic effectiveness of AM.

5

Parametric Sensitivity Analysis of Factors Affecting Sound Transmission Loss of Multi-Layered Building Elements Using Taguchi Method

80%

Garg N. , Kumar A. , Maji S.

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2014

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tom Vol. 39, No. 2

165--176

EN

The paper presents application of Taguchi method in optimizing the sound transmission loss through sandwich gypsum constructions and those comprising of masonry concrete blocks and gypsum boards in order to investigate the relative influence of the various parameters affecting the sound transmission loss. The application of Taguchi method for optimizing sound transmission loss has been rarely reported. The present work uses the results analytically predicted on “Insul” software for various sandwich material configurations as desired by each experimental run in an L8 orthogonal array. The relative importance of the parameters on single-number rating, Rw (C, Ctr) is evaluated in terms of percentage contribu- tion using Analysis of Variance (ANOVA). The ANOVA method reveals that type of studs, steel stud frame and number of gypsum layers attached are the key factors controlling the sound transmission loss characteristics of sandwich multi-layered constructions.

6

Technical Notes : Practical Concerns Associated with Single-Number Ratings in Measuring Sound Transmission Loss Properties of Partition Panels

80%

Garg N. , Kumar A. , Maji S.

Archives of Acoustics

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2013

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tom Vol. 38, No. 1

115--124

EN

The paper presents an extensive review investigating the practical aspects related to the use of single- number ratings used in describing the sound insulation performance of partition wall panels and practical complications encountered in precise measurements in extensive frequency range from 50 Hz to 5 kHz. SWOT analysis of various single number ratings is described. A laboratory investigation on a double wall partition panel combination revealed the significant dependence of STC rating on transmission loss at 125 Hz attributed to 8 dB rule. An investigation conducted on devising alternative spectrums of aircraft noise, traffic noise, vehicular horn noise and elevated metro train noise as an extension to ISO 717-1 Ctr for ascertaining the sound insulation properties of materials exclusively towards these noise sources revealed that the single-number rating Rw + Ctr calculated using ISO 717-1 Ctr gives the minimum sound insulation, when compared with Rw + Cx calculated using the alternative spectrums of aircraft noise, traffic noise, etc., which means that material provides a higher sound insulation to the other noise sources. It is also observed that spectrum adaptation term Cx calculated using the spectrum of noise sources having high sound pressure levels in lower frequencies decreases as compared to ISO 717-1 Ctr owing to significant dependence of Ctr at lower frequencies.

7

Evaluation and Analysis of Environmental Noise Pollution in Seven Major Cities of India

61%

Garg N. , Sinha A. K. , Dahiya M. , Gandhi V. , Bhardwaj R. M. , Akolkar A. B.

Archives of Acoustics

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2017

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tom Vol. 42, No. 2

175--188

EN

The paper describes the noise monitoring data acquired from the pilot project on the establishment of National Ambient Noise Monitoring Network (NANMN) across seven major cities in India for continuous noise monitoring throughout the year. The annual average Lday (06–22 h) and Lnight (22–06 h) values observed in year 2011–2014 for the 35 locations under study in which 14 locations are in commercial zone, 5 in Industrial, 7 in residential and 9 in silence zones are described. The long-term noise monitoring shows that ambient noise levels have marginally increased for 29 sites (82.9%) since past four years. The present study is focused on evaluation and analysis of environmental noise pollution at 35 noise monitoring sites in seven major cities of India and shall be instrumental in planning for the noise abatement measures for controlling the noise pollution in these sites.