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2012 - 20172
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Subject: Plant Pathology × Author: Remya, J S × End date: 2019 × Start date: 2010 ×
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    ThesisItemOpen Access
    Enhancement of systemic resistance to soil borne pathogens of ginger by enriched spent mushroom substrate of pleurotus sajor-caju
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2017) Remya, J S; KAU; Beena, S
    Spent mushroom substrate (SMS) is the composted organic material retained after a crop of mushroom. The world mushroom industry needs to discard more than 50 million tons of SMS every year. The latest research throw light on the efficient use of SMS for the disease management of crop plants. A preliminary study on the use of SMS of Pleurotus spp. as mulch for the management of rhizome rot complex disease of ginger under pot culture condition was carried out in the Department of Plant Pathology, College of Horticulture, Vellanikkara. In this study, among the various SMS used, the paddy straw SMS of P. sajor-caju as mulch recorded the highest biometric characters and least disease incidence compared to control. Hence this project was proposed as the continuation of the above study to evaluate the efficacy of enriched SMS of P. sajor-caju in enhancing growth and systemic resistance for the management of soil borne pathogens of ginger under field conditions. SMS of P. sajor-caju was produced during three different periods viz., March-April, June-July and November-December (2013) at six different locations of Kerala viz., College of Horticulture, Vellanikkara (Thrissur dist.), farmer’s field at Kodakara (Thrissur dist.), Perinjanam (Thrissur dist.), Krishnagiri (Wayanad dist.), Mananthavady (Wayanad dist.) and College of Agriculture, Vellayani (Thiruvananthapuram dist.). Enumeration of microflora of these SMS was carried out and a total of 47 fungal and 45 bacterial isolates were obtained. The antagonistic efficiency of these isolates were evaluated against the five pathogens viz., Pythium aphanidermatum, Fusarium oxysporum, Rhizoctonia solani, Sclerotium rolfsii and Ralstonia solanacearum under in vitro conditions. All the isolates from SMS showed antagonistic property against one or the other soil borne pathogens, with varying degree of inhibition. Mutual compatibility between the most efficient fungal and bacterial antagonists was evaluated to develop an effective microbial consortium for enriching the SMS and could be used against the soil borne diseases of ginger. Biosoftening efficiency of selected fungal and bacterial antagonists on SMS was evaluated. Two separate experiments were carried out with the selected antagonists effective against fungal and bacterial pathogens. For each experiment, five fungal antagonists, five bacterial antagonists and three compatible pairs were selected based on the in vitro evaluation of antagonistic efficiency and mutual compatibility studies. SMS was enriched separately with different antagonists and standardized the period for biosoftening of SMS as mulch for ginger cultivation. A period of 15 days was selected as most suitable for biosoftening the SMS as mulch with optimum antagonistic fungal and bacterial population. Wide range of C:N ratio was recorded by the SMS enriched with each antagonists. By considering the C:N ratio along with external appearance, the treatments having C:N ratio of 30:1 to 45:1 were selected, since it was the most suitable stage to be used as mulch in ginger. The effectiveness of biosoftened SMS against rhizome rot and bacterial wilt diseases of ginger was evaluated in two pot culture experiments. Three fungal and bacterial antagonists each and one compatible pair of antagonists which were selected based on the in vitro evaluation of antagonistic and biosoftening property were used for enriching the SMS. After enrichment, the SMS were kept for 15 days for biosoftening and were applied as mulch in the experiments. Observations on germination percentage and other growth parameters viz., number of tillers/plant, number of leaves/tiller and height of tillers were recorded at one month intervals from two months after planting (MAP). Challenge inoculation of pathogens was done at 45 days after germination and per cent disease incidence was recorded at 7 and 14 days after inoculation (DAI). In the experiment for the management of P. aphanidermatum, the lowest disease incidence was observed in T7 (SMS softened with P1F1+ M1F2) on 14th day after inoculation (DAI). This treatment also recorded the highest number of tillers, number of leaves/ tiller and height of tillers and rhizome yield. In the experiment for the management of R. solanacearum, the treatment T2 (SMS softened with T1F2) was found to be the most efficient one, which recorded the least disease incidence at 14 DAI, whereas the highest values for biometric characters and rhizome yield were recorded by T7 (SMS softened with K1B1 + T2B1). The activity of phenol and defense related enzymes such as peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were estimated by spectroscopy, before challenge inoculation with pathogen and at one, three and five days after the challenge inoculation. For estimation, leaf samples were collected separately from the pot culture experiments I and II for the management of P. aphanidermatum and R. solanacearum respectively. The treatments which recorded less disease incidence in both the pot culture experiments exhibited the highest activity of defense related enzymes and phenol. The highest activity of defense related enzymes and phenol was recorded at 5 DAI. Thus the present study showed that in addition to direct antagonism and plant growth promotion, induction of defense related enzymes was also contributed by SMS to enhance resistance against invasion of soil borne pathogens of ginger. Field evaluation of the selected treatments from pot culture experiments showed the lowest disease incidence in the treatment T2 (SMS softened with T1F2) followed by T5 (SMS softened with P1F1+M1F2). Statistically these were on par with each other. The treatment T5 (SMS softened with P1F1+M1F2) recorded the highest germination percentage, number of tillers, number of leaves/tiller and rhizome yield also. Analysis of primary nutrients viz., nitrogen, phosphorus and potassium in SMS, plant and soil from field experiment was conducted. Among these, SMS softened with P1F1+M1F2 recorded the highest percentage of N, P and K. This treatment recorded the highest nutrient content in ginger rhizome and soil also. Attempts were also made to identify the fungal and bacterial antagonists selected for field experiment. Based on the cultural and morphological characters, the fungal antagonists viz., Kr1F4, T1F2, P1F1 and M1F2 were tentatively identified as Trichoderma viride (Pers.), T. viride (Pers.), T. koningii (Oudem.) and T. harzianum (Rifai) respectively. The identification got confirmed from National Centre for Fungal Taxonomy (NCFT), New Delhi. The bacterial antagonists selected for field experiment were also identified based on cultural, morphological, biochemical and 16s rRNA sequence analysis. The three bacterial antagonists P3B2, T2B1 and K1B1 were identified as Bacillus safensis, B. methylotrophicus and Burkholderia gladioli respectively. Spent mushroom substrate is rich in microflora and these microflora exert antagonistic activities against soil borne pathogens. It stimulates the natural defense system in plants, provide necessary nutrients for plant growth and also improve soil physical condition. From field evaluation it was found that the SMS softened with T. viride recorded the lowest disease incidence and which enhanced systemic resistance to soil borne pathogens of ginger by defense related enzymes and phenol. The results were on par with the SMS softened with consortium of antagonists, T. koningii and T. harzianum (P1F1+M1F2). The highest rhizome yield and other growth parameters were also contributed by the SMS softened with T. koningii and T. harzianum. The content of nitrogen, phosphorus and potassium were also recorded the highest in this SMS. So from the present study it can be concluded that the SMS softened with T. koningii and T. harzianum can be used as mulch in ginger which was found equally effective to induce systemic resistance against soil borne pathogens and to enhance growth parameters and rhizome yield.
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    ThesisItemOpen Access
    Exploitation of spent mushroom substrate as mulch for the management of rhizome rot complex disease of ginger
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2012) Remya, J S; KAU; Sheela Paul, T
    Spent mushroom substrate (SMS) is the composted organic material remained after the harvest of a crop of mushroom and it is rich in plant nutrients including minerals and was used as manure in different crops including ginger. Recent findings illustrate that substrate after one cycle cultivation of mushroom can be used for disease management. So far no attempt has been made on the use of spent mushroom substrate from oyster mushroom, against rhizome rot complex disease of ginger. Under these circumstances, a study was conducted to know the effectiveness of oyster mushroom SMS to control the rhizome rot complex disease of ginger. Bacterial wilt and soft rot are the two common rhizome rot diseases of ginger. Ginger plants showing typical wilt symptoms and soft rot symptoms were collected from the farmer’s field. The fungal pathogen Pythium aphanidermatum and the bacterial pathogen, Ralstonia solanacearum were isolated from the rhizomes showing typical symptoms, and pure cultures were maintained. Since Pleurotus florida and P. sajor-caju are the most suitable mushroom species in Kerala, they were selected for the production of spent mushroom substrate. The substrate used were agricultural waste materials like paddy straw, saw dust and neopeat. The enumeration of microorganisms at different stages of mushroom growth were made and the fungi commonly observed were Aspergillus sp. (FA-2 and FA-3) and Trichoderma sp. (FA-1). Maximum number of microbial population was noticed in paddy straw, whereas it was minimum in neopeat. From four different stages of mushroom growth, five different types of bacteria, BA-1, BA-2, BA-3, BA-4 and BA-5 were observed. An in vitro evaluation study was conducted to find out the efficiency of isolated organisms against the pathogens P. aphanidermatum and R. solanacearum. Among the bacterial isolates tested against P. aphanidermatum, BA-4 and BA-5 were effective, whereas against R. solanacearum, only BA-5 was found effective. All the three fungal isolates, FA-1, FA-2 and FA-3 gave 100 per cent inhibition against both the pathogens. But FA-1 was the most effective one. These five antagonists were selected for the compatibility studies by dual culture technique. The selected fungal antagonist FA-1 was identified as Trichoderma viride by studying cultural and morphological characters. The bacterial isolates BA-4 and BA-5 were identified as Pseudomonas aeruginosa and Klebsiella pneumoniae respectively. The effect of spent mushroom substrate for the management of rhizome rot complex disease of ginger was assessed under pot culture conditions. Two separate experiments were conducted for the management of P. aphanidermatum and R. solanacearum. All the treatments were applied at three times- at the time of planting, 60 DAP and 120 DAP. Among the various treatments for the management of both the pathogens associated with rhizome rot complex disease, T. viride from SMS and paddy straw SMS of P. sajor-caju as mulch were found to be the best giving cent per cent disease control. In control treatment, cent per cent disease incidence was noticed. In the experiment for the management of P. aphanidermatum, hundred per cent germination was noticed in the treatment, T. viride from SMS + Reference culture T. viride. Among the treatments with SMS as mulch, paddy straw SMS of P. sajor-caju showed better germination percentage. But in the experiment for the management of R. solanacearum, the treatment Klebsiella pneumoniae showed 100 per cent germination followed by the treatment T. viride from SMS. The growth parameters like number of tillers, number of leaves per tiller and height of tillers were highest in the treatment T. viride from SMS, at two, three, four and five months of planting, in the experiment for the management of P. aphanidermatum. But in the experiment for the management of R. solanacearum, the treatment paddy straw SMS of P. sajor-caju as mulch showed highest number of tillers. Number of leaves per tiller was highest in the treatment K. pneumoniae + reference culture P. fluorescens, in the first three months and the treatment with paddy straw SMS of P. sajor-caju as mulch for the next two months. Height of tillers was observed maximum in the treatments applied with T. viride from SMS. The same trend was noticed in the case of yield also. In the experiment for the management of P. aphanidermatum, highest yield was observed in the treatment T. viride from SMS. But in the experiment for the management of R. solanacearum, the treatment paddy straw SMS of P. sajor-caju as mulch produced highest yield. SMS is rich in microflora with antagonistic effect against pathogenic microorganisms associated with ginger plants. From the pot culture experiment it was clear that for the management of R. solanacearum and plant growth promotion, best treatment is paddy straw SMS of P. sajor-caju as mulch. High cellulolytic capacity of P. sajor-caju favour the maximum degradation of the substrate, thereby provides a niche for the multiplication of favourable microorganisms with antagonistic effect. Whereas, best treatment for the management of P. aphanidermatum and plant growth enhancement is T. viride from SMS. It was found to be better than reference culture T. viride. In addition the beneficial microorganisms may be having plant growth promoting activity which contributes to increased yield in the various treatments. So from the present study, it can be concluded that the use of paddy straw SMS of P. sajor-caju as mulch, along with the application of T. viride from SMS can be considered as an effective management practice against the rhizome rot complex disease of ginger. Depending on the location and climatic condition in which the mushroom crop is raised, the microorganisms harbouring in SMS will vary and they can be used for disease management in various crops.