GAUTAM, H.R.SHARMA, KISHOR2018-07-162018-07-162018-06-26http://krishikosh.egranth.ac.in/handle/1/5810060289ABSTRACT The present investigation titled “Potential of plant extract based silver nanoparticles for the management of green mould (Penicillium digitatum) of citrus” was conducted in the laboratories of the Department of Plant Pathology, experimental orchards of Dr. YSP, University of Horticulture and Forestry (RHR&TS) at Jachh. During the survey of the disease, incidence of green mould rot ranged between 16.5 to 27.0 per cent recorded. Average severity of disease was recorded maximum in Paonta Sahib (21.33%). Silver nanoparticles were synthesized from tulsi and neem leaf extract. Reduction of silver nanoparticles during exposure to plant extract was observed as result of colour change from light brown then to dark reddish brown. In case of O. americanum origin SNPs, absolute absorption peak was obtained at 448 nm which confirmed the reduction of AgNO3 in to silver nanoparticles. In case of SNPs synthesized from neem, the band concentrated around 442 nm. SNPs synthesized from tulsi were spherical to irregular in shape and size distribution in case of tulsi ranged between 100-250 nm and neem were also spherical to irregular in shape and size distribution ranged between 150-500 nm. Atomic force microscope image of tulsi SNPs indicated the height of sub-microscopic spherical to irregular shape silver nanoparticles ranging from 300 nm to 500 nm and 150-250 nm in case of neem SNPs. In Transmission electron microscopy (TEM) studies, the size of the SNPs of tulsi ranged between 22.8 to 70.0 nm. While, in case of neem, the size of the SNPs ranged between 26.5 nm to 85.0 nm. Aqueous leaf extract of Ocimum americanum was found most effective and significantly superior amongst all the treatments with 58.6 per cent average mycelial growth inhibition. SNPs of O. americanum origin silver nanoparticles proved most effective followed by A. indica origin SNP’s with 80.7 and 77.4 per cent mycelial growth inhibition at 1000 ppm concentration. Among sixteen treatments, treatment comprising of water extract of tulsi SNPs (1000 ppm) + water extract (10%) of tulsi was found most effective with no incidence of green mould rot, restriction in lesion size (98.85%), effective in retaining minimum fruit TSS (12.68oBrix), maximum titratable acidity (1.01%) and Minimum physiological loss in weight (2.94%) after 30 days of storage. Foliar sprays of treatment comprising of tulsi SNPs (1000 ppm) and water extract (10%) of tulsi and treatment comprising of neem SNPs (1000 ppm) and water extract (10%) of neem were found at par with the treatment where fruits were treated with fungicide (Score) with no incidence of green and blue mould on the fruits after 30 days of storage.ennullThesis