CHARACTERIZATION OF VOLATILE ORGANIC COMPOUNDS (VOCs) PRODUCED BY BIOAGENTS AND POSTHARVEST MANAGEMENT OF FRUIT ROT IN GRAPES
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Date
2022-12-06
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University of Agricultural Sciences, Bangalore
Abstract
Grapes (Vitis vinifera L.) is an important fruit crop belonging to the family Vitaceae. Even though grapes fruits are prone to a number of diseases, fungal pathogens inflict greater losses. Grapes fruits are extremely susceptible to postharvest spoilage because of its perishable nature. The causal agent of the important postharvest pathogens of grapes were isolated and identified as Alternariaalternata,Colletotrichumgloeosporioides and Penicilliumcitrinum. Their identity was confirmed at molecular level. Twenty-nine bacterial and two yeast epiphytes were isolated from the phylloplane and fructoplane of grapes and screened them for their antagonistic effect against postharvest pathogens of grapes. Among them fifteen bacterial and two yeast isolates were found effective and they were identified at molecular level and characterized biochemically. After excluding three opportunistic bacterial pathogen isolates, remaining fourteen isolates were tested for the production of VOCs and among them threebacterial (Bacillus spp.) and two yeast isolates (Hanseniosporaopuntiae)
were effective in the production of anti-fungal volatiles suitable for the postharvest disease management. The VOCs viz., styrene, aceticacid 2-phenylether ester, azulene, n-hexadecanoic
acid, beta- cubebene, trans- beta bergamotene, beta- phyllandrene and benzene propyl were
identified from effective antagonists in pure culture and during their interaction with pathogen using solid phase microextraction -gas chromatography and mass spectrometry (SPMEGCMS). Based on the commercial availability of the VOCs, n- hexadecanoic acid (palmitic acid) was selected for further work and at higher concentration (20%), and inhibited the radial growth of target pathogens significantly. Exposure of grapes fruits (cv. Dilkush) to the volatiles of IIHR_MIFY01 and IIHR_GSPB02 and fruits of cv. Sonaka to 20 per cent of palmitic acid was found effective in reducing the postharvest diseases and maintaining the shelf life and quality of grapes fruits.