STUDIES ON ALTERNARIA FRUIT ROT OF CHILLI

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dc.contributor.advisorDr. J. KRISHNA PRASADJI
dc.contributor.authorUSHAM SUDHEINA SINGH
dc.date.accessioned2017-10-12T06:39:36Z
dc.date.available2017-10-12T06:39:36Z
dc.date.issued2015
dc.descriptionD5196en_US
dc.description.abstractAlternaria fruit rot of chilli caused by Alternaria alternata (Fr.) Keissler is prevalent in most of the chilli growing regions of Guntur district of Andhra Pradesh, India. The incidence and severity (PDI) of Alternaria fruit rot were in the range of 2.19 to 10.49% and 0.83 to 8.42, respectively, while the corresponding incidence and severity of Colletotrichum fruit rot were 3.41 to 14.17% and 1.26 to 8.96%, respectively in 25 locations on nine chilli varieties during Kharif 2013-14 in Guntur district. Symptoms were found to be distinct for both Colletotrichum fruit rot and Alternaria fruit rot. Generally one or occasionally two to three elliptical spots surrounded by bleached tissue was characteristic of Colletotrichum fruit rot. One to three generally circular spots without bleached tissues were found to be the typical symptoms of Alternaria fruit rot. None of the fruits was found infected by both pathogens at any stage of investigation. Both the pathogens were also found to be both externally and internally seed borne in almost all the varieties and in all mandals of the district surveyed. Association of A. alternata with chilli seeds ranged from 0% to 47.00% (mean, 20.08%) as externally seed borne and 0% to 25.00% (mean, 8.20%) as internally seed borne while that of C. capsici varied from 0% to 67.00% (mean, 30.00%) as externally seed borne and 0% to 45.00% (mean, 17.84%) as internally seed borne. Other fungal flora infesting chilli seeds were Fusarium spp., Aspergillus spp. and Curvularia spp. at very low frequency. The seed mycoflora of chilli exhibited different distribution pattern as externally and internally seed borne and among which Colletotrichum and Alternaria had higher colonizing frequency (CF) and isolation recovery (IR) irrespective of location and variety. For externally seed borne mycoflora the highest Simpsion’s diversity index (DI=0.585) and Shannon-Wiener diversity index (H’=1.040) were in seed samples from Thullur mandal and Sattenapalli mandal, respectively. The species richness was the greatest in seeds from Amravati mandal (0.516) but more uniform in seed samples from Sattenapalli mandal with the highest species evenness (0.646). Among varieties the highest DI (0.614) and H’ (1.100) were in seeds from Byadagi variety while the greatest species richness (0.763) and species evenness (0.683) were in varieties LCA-577 and Byadagi, respectively. The highest diversity of internally seed borne fungi was in seeds from Piduguralla mandal with the highest DI (0.519) and H’ (0.853) values while the greatest species richness (1.508) and evenness (0.530) were in seeds from Amaravati mandal and Piduguralla mandal, respectively. Among varieties, mycofloral diversity in Avatar variety was the highest in terms of DI (0.531) while the highest H’ (0.875) was in Byadagi variety while species richness was the highest in Sarada variety (1.768) and evenness in Byadagi variety (0.544). Studies corroborated the seed borne nature of both fruit rot pathogens despite encountering competition from other saprophytes associated with chilli seed. In vitro study of interaction between A. alternata and C. capsici on detached matured transition stage chilli fruits revealed dominance of A. alternata over C. capsici which accounted to its greater necrotrophic nature of nutrition and preference of senescing and injured tissues than C. capsici. Colletotrichum fruit rot incidence increased with age of the crop and was in the range of 19.98 to 35.80% at 187 DAT. Based on incidence three genotypes viz., LCA 334, LCA 436 and G4 were categorized as moderately resistant. However, based on severity all the genotypes were grouped under the moderately resistant category. Progress of Alternaria fruit rot incidence was similar but started later to Colletotrichum fruit rot and ranged from 34.13 to 69.68% at 194 DAT. Severity of Alternaria fruit rot in terms of PDI was between 31.93 and 58.24 based on which all the genotypes were categorized as either susceptible or highly susceptible. Among the various biochemical and nutrient content of chilli fruits only total phenol and calcium content showed significant negative correlation with severity (PDI) of Alternaria fruit rot of chilli. Benomyl (0.05%) either alone or in combination with either Trichoderma harzianum (108 spores/ml) or gingelly oil (0.5%) significantly reduced incidence and severity of post harvest Alternaria fruit rot of chilli. Benomyl reduced incidence by 70.58% and severity by 83.02%.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810032950
dc.keywordsALTERNARIA, FRUIT ROT, CHILLIen_US
dc.language.isoen_USen_US
dc.pages157en_US
dc.publisherAcharya N.G. Ranga Agricultural University, Gunturen_US
dc.research.problemSTUDIES ON ALTERNARIA FRUIT ROT OF CHILLIen_US
dc.subPlant Pathologyen_US
dc.subjectnullen_US
dc.themeSTUDIES ON ALTERNARIA FRUIT ROT OF CHILLIen_US
dc.these.typeM.Scen_US
dc.titleSTUDIES ON ALTERNARIA FRUIT ROT OF CHILLIen_US
dc.typeThesisen_US
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