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Biodiversity of Diazotrophs in Rhizosphere of Potato Solanum Tuberosum L.

Thesis Info

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Author

Naqqash, Tahir.

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Natural Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9446/1/Tahir%20Naqqash%20-%20Thesis.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725607284

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Potato is the third most important food crop which requires high fertilizer that leads to environmental pollution. The use of biofertilizer is environment friendly and cost effective hence is suitable for sustainable agriculture. In this study, 44 bacterial isolates including mostly Azospirillum, Bacillus, Brevundimonas, Enterobacter, Pseudomonas and Rhizobium spp. were isolated from potato rhizosphere of which 32 were able to fix atmospheric N2 and 29 showed indole acetic acid (IAA) production. Strains showed high metabolic and genetic diversity based on BioLog, ERIC and BOX-PCR analysis. Out of potential plant growth promoting rhizobacteria (PGPR) tested for inoculation response in potato, it was observed that the N2 fixation (%Ndfa) decreases with the increase in applied N for Rhizobium sp. TN04 and Azospirillum sp. TN09 whereas no effect was observed for Azospirillum sp. TN03. Azospirillum sp. TN09 showed the highest %Ndfa among three tested isolates. Under field conditions, Azospirillum spp. TN03, TN09 and Rhizobium sp. TN04, Rhizobium sp. TN04 increased plant height (18%), dry weight (18.5%) tuber dry weight (14%) and tuber yield (19%). Azospirillum, Brevundimonas and Rhizobium spp. also maintain substantial population with potato roots. Metagenomics were employed to study total bacterial diversity in the rhizosphere of potato from major potato growing areas of Punjab, Pakistan showed that structural community (based on 16S rRNA) is almost similar across all the regions whereas functional diversity (based on nifH) of diazotrophs is mostly variable. Abundance of diazotrophs (108-1010 copies of nifH g-1 of soil) changed among regions. Pyrosequencing of nifH validated maximum diversity in Sheikhupura (446 species) whereas minimum in Gujranwala area (291 species). Overall in the potato rhizosphere, most abundant class was α-proteobacteria followed by β-proteobacteria. The study concludes that abundance of different genera varies across different regions due to many biotic and abiotic factors. Azospirillum spp. TN03, TN09 and Rhizobium sp. TN04 omnipresent and have potential to improve potato yield up to 15-19% subsequently saving 50% nitrogenous fertilizer, are recommended as potential candidates for biofertilizer production for potato crop. The study also shows that potato xvi harbor a diverse range of novel diazotrophs (not known earlier) which opens new horizons for future prospects.
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ہم کہ زندانی ہیں جس کے پیار کے

ہم کہ زندانی ہیں جس کے پیار کے
چھیڑیے قصے نگاہِ یار کے

موت کی وادی ہے جلوہ حسن کا
عشق کے سب دائرے ہیں دار کے

آنکھ کے تیور، مَیں اُن کے کیا کہوں
دل جگر چھلنی ہیں اس تلوار کے

اُن سے دوری جان لیوا ہو گئی
قرب کے وعدے تھے مجھ سے یار کے

تم فضاؔ مجھ زیست کا سامان ہو
اولیں ہو آخریں بھی پیار کے

Cognitive Semantic Study of the Preposition ‘Min’ in the Quran

The preposition ‘min’ is semantically more complex than what the traditional lexicaAl-syntactic approaches held it to be adverb or adverbial of place and time. This paper attempts to investigate the semantic complexity of the preposition ‘min’ from cognitive linguistic perspective to find out its semantic classification and linguistic symmetric patterns. Data has been taken from the Quran to investigate the claim of conceptual metaphor theory that sensorimotor neural structures generates the preposition ‘min’ on the image schema of source-path-goal. The findings reveal that the source-pathgoal image schema is not only at work in the use of preposition ‘min’ in spatio-geometric sense, but also to map the abstract concepts, emotional states and relationship with supernatural entities in spatial terms in the Quran. However, the data also show idiosyncratic behaviour of preposition, attaining different semantic arguments in different linguistic contexts, which strengthen the argument that language use cannot be abridged to static mapping in the human conceptual system. This paper recommends future research on the same preposition or other prepositions to investigate further the source-path-goal image schema in the Quran and Arabic language.

Biochemical Studies of Flavonids and Related Compounds

Flavonoids are the most common group of polyphenolic compounds in the human diet including fruits, vegetables, nuts and plant derived beverages, tea and wine. These compounds have been reported to possess a wide range of bio-activities. Structural variations of these flavonoids are associated with many different biological and pharmacological activities including antioxidant, anticancer, antiinflamatory, antihyperglycemic, antidiabetic, antibacterial, antifungal and antiviral activities. Antioxidant enzymes as well as non enzymatic antioxidants are the first line of defense against oxidative stress. This oxidative stress is the underline mechanism for diabetic complications. In recent years, the high therapeutic properties of flavonoids and their analogues have brought attention of chemists to synthesize various kinds of their derivatives by improving the existing synthetic methodologies.It is therefore, the aim of present study was to synthesis and characterize the novel flavonoids and their derivatives. These compounds were screened for their antioxidants potential and evaluate their antihyperglycemic activity. By using Claisen−Schmidt condensation, 2,5-dihydroxyacetophenone was allowed to condense with different aromatic aldehydes. Four kinds of products were isolated; chalcones (105, 106, 108, 110, 115, 119, 121), flavanones (107, 109, 111, 120, 123), Arylmethylidene flavanone (112, 113, 114, 116, 117, 118, 122, 124, 127, 128) and 2-Arylmethylidene indanones (125, 126). A series of chalcones (131-135) was also synthesized by reacting 2 hydroxy-5-nitro acetophenone with different aromatic aldehydes. The synthesized chalcones 134 underwent cyclization in the presence of iodine to obtain compound 136. Compound 105 was reacted with hydrazine hydrate to obtain 2-(5-(2-nitrophenyl)4,5-dihydro-1H-pyrazol-3 yl)benzene-1,4-diol (129) and compound 108 was reacted with hydrazine hydrate to form 2 (5-(4-nitrophenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl)benzene-1,4-diol (130). The compound (125) was reacted with different N-substituted-2-bromoacetamide (137-139) to form compound (144-146). After reacting 8-acetyl-7-hydroxy-4-methylcoumarin (142) with 2′-Bromo-N-benzylacetamide (137), the product 2-[(8-acetyl-4-methyl-2-oxo-2H-chromen 7-yl)-oxy]-N-phenylacetamide (143) was obtained. All the synthesized compounds were characterized and confirmed through spectroscopic analysis i.e., Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR) spectroscopy and Electron Ionization Mass Spectrometry (EIMS). The compounds 105-126, 129, 130 and 131-135 were checked for their antioxidant potential by α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging, Iron chelating activity, Iron chloride (FeCl3) reducing power activity, Phosphomolybdinum assay and 2,2′ azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activity. Among all the synthesized compounds, the chalcones 105, 106, 108, 110, 115, 119, and 121 showed excellent antioxidant activity. The chalcones 105, 110 and 115 exhibited better antioxidative behavior than trolox and ascorbic acid. The Oral glucose tolerance test (OGTT) was performed in normal hyperglycemic rats for compounds 105, 106, 107, 108 and 109. The compound 109 exhibited good activity in normal hyperglycemic rats while the compound 105 showed significant activity in streptozotocin (STZ) induced diabetic rats as compared to reference Glabenclamide. For in silico studies, Quantitative Structure-Activity Relationships (QSAR) were performed for compounds 105-126 and 131-135. The comprehensive intra molecular charge transfer has been perceived from the highest occupied molecular orbitals (HOMOs) to the lowest unoccupied molecular orbitals (LUMOs). The smaller ionization potential (IP) and bond dissociation energy (BDE) values for compound 105, 106, 107, 108 and 109 revealed that these compounds would show proficient antioxidant behavior which is in good agreement with the antioxidant experimental data. Experimental and computational investigations concluded that compound 105 might be an effective antihyperglycemic agent because of its antioxidative nature and smallest ionization potential.