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Researcher Panchal, B. J.
Advisor Jha, Sanjay
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Doctor of Philosophy (Ph.D.)
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Biotechnology and Molecular Biology ♦ Ph.d. Thesis
Abstract Phosphorus (P) is a major growth-limiting nutrient, which is rapidly made immobile and less available for plant use after addition to the soil as a soluble fertiliser. Large amount of P applied as fertilizer enters in to the immobile pools through precipitation reaction with highly reactive Al3+ and Fe3+ in acidic, and Ca2+ in calcareous or normal soils. Efficiency of P fertilizer throughout the world is around 10 - 25 % and concentration of bioavailable P in soil is very low reaching the level of 1.0 mg kg–1 soil. Phosphate-solubilising microorganisms (PSMs) play a key role in soil P dynamics and subsequent availability of phosphate to plants. There are strong evidences that soil fungi are capable of transforming soil P to the forms available to plant. Eight efficient phosphorus solubilizing fungi (PSF) were isolated from the rhizosphere of different weeds, which are capable of utilizing sucrose and rock phosphate as the sole carbon and phosphate source, respectively in buffered 100mM tris minimal rock phosphate (TRP) media (pH-8.0). All isolates under study released inorganic phosphate from rock phosphate. The P solubilizing potential of PSF was tested under in-vitro and in-vivo conditions. Cunninghamella spp. and Fomitopsis spp. exhibited the maximum and constant P solubilization potential throughout the incubation period in the presence of rock phosphate in TRP medium. The potential of P-solubilization by PSF ranged from 536.80µM to 1020.36µM in liquid medium. Constant enhancement in P solubilizing activity at different incubation period was recorded. The capacity to solubilize inorganic phosphate by these PSF can be attributed to the secretion of organic acids (gluconic acid, succinic acid, oxalic acid and acetic acid), to determine their presence in the cultures supernatant, reverse-phase high performance liquid chromatography was performed. The mechanism of this organic acid production was studied by analysing the enzymes invertase (BFF), glucose oxidase, isocitrate lyase and oxaloacetate. These PSF exhibited plant growth promoting activity by producing plant growth stimulator, Indole-3-Acetic Acid (IAA) (1097.7 µg ml-1) and siderophore production. Efficacy of the isolates on nutrient availability as well as on growth promotion of tomato and moth bean crops was confirmed by pot experiments. Results obtained show that in inoculated pots the overall plant growth was higher compared to un-inoculated pots. Fomitopsis sp. NAU-B2 and Cunninghemella sp. NAU-B5 inoculated plants showed best performances during tomato and moth bean pot experiment. These two PSFs isolates promoted plant growth and also suppressed fusarium wilt disease in tomato root by significantly increasing the level of jasmonic acid. The result indicates that the effective strains of Fomitopsis sp. and Cunninghemella sp. could be used for nutrient availability and crop production.
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Size (in Bytes) 29.84 MB
Page Count 126