Characterization of rhizosphere and endophytic microflora from organically grown amaranth for management of leaf spot diseases
| dc.contributor.advisor | Sainamole, Kurian P | |
| dc.contributor.author | Aparna, V S | |
| dc.contributor.author | KAU | |
| dc.date.accessioned | 2017-08-26T10:32:59Z | |
| dc.date.available | 2017-08-26T10:32:59Z | |
| dc.date.issued | 2015 | |
| dc.description.abstract | Amaranth is the most important and popular leafy vegetable of Kerala. Rapid growth, quick rejuvenation after each harvest, higher yield per unit area and easiness in cultivation make it the cheapest vegetable which is rightly described as the ‘poor man’s spinach’. However, leaf spots and blights caused by fungal pathogens are serious threats to amaranth growers. The present investigation was carried out to explore the influence of various organic sources of nutrients on leaf spot diseases and to characterize potential antagonists from organically grown amaranth for management of these diseases. During the study, the pathogen causing leaf blight disease was isolated as this was the only foliar disease observed on amaranth plants grown for the field experiment. The cultural and morphological characters of the pathogen along with pathogenicity on amaranth confirmed it as Rhizoctonia solani (Kuhn). Population of fungi, bacteria and actinomycetes present in different organic sources of nutrients viz., farm yard manure, neem cake, vermicompost and poultry manure were estimated. Poultry manure contained the highest number of microflora per unit weight. A field experiment was conducted to study the effect of different organic sources of nutrients on leaf blight, growth and yield of amaranth. The results revealed that, there was no significant difference among organic sources of nutrients on disease severity. However, rate of growth indicated by various biometric parameters was the highest in plants grown with poultry manure (T5) as organic nutrient source. The population of rhizosphere microflora was estimated at periodical intervals i.e. pre-treatment, 30, 60 and 75 days after transplanting. The results revealed that, after application of organic sources of nutrients the microflora increased in the rhizosphere up to 60 days after transplanting. Bacteria were predominant in rhizosphere followed by fungi and actinomycetes. The pre-treatment fungal, bacterial, fluorescent pseudomonad and actinomycete population was not significantly different. But the population varied significantly among the treatments throughout the period of experiment. The endophytic microorganisms from stem and roots showed that endophytes were lesser in number compared to rhizosphere microorganisms and bacteria are predominant in the endosphere of amaranth plants. In general, both fungi and bacteria are more in roots. Actinomycetes could not be isolated from any of the samples. Based on colony characters, 123 different isolates were collected from rhizosphere and endosphere of amaranth plants in which 25 fungal and 36 bacterial isolates showed antagonistic activity against R. solani. These were further evaluated under dual culture. From rhizosphere the bacterial isolate RB-21(65.33%) had the highest per cent inhibition against R. solani immediately followed by RB-14 (63.33%). From endosphere EB-2 (62.66%) showed maximum per cent inhibition and the fungal isolate, EF-8 recorded cent per cent inhibition of the pathogen. These were selected for evaluation in pot culture experiment. A pot culture experiment was conducted to study the efficacy of organic sources of nutrients and selected antagonists on management of leaf blight of amaranth. Even though there was 100 per cent disease incidence in all the treatments, significant difference was observed in the case of per cent disease severity. The plants treated with RB-14 (T8) at 15 DAT, EF-8 (T9) at 30 DAT and RB-14 (T6) at 45 DAT exhibited less disease severity during the period of experiment. It was observed that T10 (Trichoderma viride of KAU) had the highest value for most of the biometric parameters and T9 (EF-8) was the second best in promoting plant growth. Based on cultural, morphological and biochemical properties, the selected bacterial isolates, RB-21 and RB-14 were tentatively identified as fluorescent Pseudomonas sp. and EB-2 as non-fluorescent Pseudomonas sp. Based on conidia and conidiophore characters, the fungal isolate (EF-8) was identified as Trichoderma sp. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810029776 | |
| dc.keywords | Plant pathology | en_US |
| dc.language.iso | en | en_US |
| dc.publisher | College of Horticulture, Vellanikkara | en_US |
| dc.sub | Plant Pathology | en_US |
| dc.subject | null | en_US |
| dc.theme | endophytic microflora from organically grown amaranth for management of leaf spot diseases | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Characterization of rhizosphere and endophytic microflora from organically grown amaranth for management of leaf spot diseases | en_US |
| dc.type | Thesis | en_US |