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Subject: Plant Pathology × End date: 1982 × Start date: 1982 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Studies on the microflora of stored pepper
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Estelitta, S; KAU; Abi Cheeran
    With a view to study the microflora in stored black pepper, a research project was carried out at the College of Horticulture, Vellanikkara. It was also aimed at estimating the deterioration of the quality of stored black pepper in terms of its oleoresin, piperine and starch contents due to microbial infection and assessing the role of each micro-organisms in changing the quality of the product. The study revealed that the major chemical constituents of stored black pepper, namely, oleoresin, piperine and starch varied in different grades of black pepper. Slight variations in these quality constituents were observed according to the seasons of storage also. In all the seasons, association of microflora with all grades of black pepper was observed. The species of micro-organisms were not changed during seasons, but the population varied according to grade of black pepper and season of storage. The micro-organisms found were Aspergillus niger, A. candidus, A. nidulans, A. versicolor, curvularia lumata, penicillium citrinum, Fusarium moniliforme, Rhizopus nigricans and Bacterium (gram –ve). There was no growth of microflora in stored black pepper upto 66.8 per cent relative humidity, whereas profused growth was observed at saturation levels of humidity. Only Aspergillus spp. And penicillium citrinum could come up at a lower HUMIDITY LEVEL (75.6 per cent). In three quality constituents of black pepper viz., oleoresin, piperine and starch reduced considerably when the samples were inoculated with different micro-organisms at different levels of humidity. Reduction in the quality constituents was found corresponding to the increase in level of humidity as well as length of incubation period.
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    ThesisItemOpen Access
    Studies on host-varietal specificity for Rhizobium for nodulation in groundnut
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1982) Girija, V K; KAU; Sasi Kumar, Nair
    An investigation was carried out at the College of Agriculture, Vellayani, Kerala to study the host-varietal specificity, if any, for Rhizobium for nodulation in groundnut. A total of fifteen groundnut varieties were subjected to a preliminary screening on the basis of the number of nodules formed and arranged into five distinct nodulation groups. Seven varieties of groundnut TMV-12, USA-123 Exotic-6, Spanish Peanut, TMV -11, Ak12-24 and Ah-32 were selected from among these groups for use in further studies.
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    ThesisItemOpen Access
    Study on the etiology and ecology of "Fungal Pollu" in pepper
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Sebastian, K V; KAU; Abi Cheeran
    Laborartory and field experiments of the " study on the etiology and ecology of fungal pollution' was found to be Colletotrichum gloeosporiodes. The initial symptom of the disease observed on leaves tender shoots and berries was chlorotic specks. Only physiologically active leaves were infected. The well developed leaf spot under dry condition were circular to irregularly circular in shape. Under humid moisture conditions, the leaf spot enlarged quickly and the holonecrotic area was ashy white in colour. Pedicel infection caused the shedding of the spike. Infected tender shoots dried. Rachis infection was noticed rarely. The infected berries became dried, shrivelled, dark in colour and light in weight. Infection on mature berriescaused cracking of the rind.
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    ThesisItemOpen Access
    Investigation on the edible species of Coprinus and standardisation of techniques for its large scale artificial cultivation
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1982) Geetha, D; KAU; Chandrasekharan Nair, M
    A survey conducted in and around the college of Agriculture, Vellayani Campus revealed that the commonly occurring species of Coprinus were Coprinus lagopus (Fr.) Fr. C.disseiminatus (Pero. ex Fr.) S F Gray and C.ephemorus (Bull.ox Fr.) Fr. and among these, the most commonly occurring species was C.lsgopus. The culture of c.lagopus used for the present study was isolated from paddy straw beds of Volvarlella volvocea raised at the Department of plant Pathology and maintained on potato dextrose agar slants by subculturing periodically.
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    ThesisItemOpen Access
    Survey of collateral hosts of Phytophthora palmivora (Butler) butler in pepper gardens
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Manomohan, Das T P; KAU; Abi, Cheeran
    A survey work was conducted at six locations of north Kerala to identify the collateral hosts of Phytophthora palmivora, the causal agent of quick wilt disease of pepper, especially the weeds and economical plants growing in and around the pepper gardens. The locations were surveyed at monthly intervals during the period from May, 1981 to December, 1981. Pepper was found to be infected by Phytophthora species in all the locations surveyed. Both aerial and underground parts of the vine got infected showing typical quick wilt symptoms. The gardens in the vicinity of arecanut and rubber plantations showed heavy incidence of the disease. The Phytophthora species collected from pepper from the different locations showed similar morphological characters and were identified as P. palmivora. None of these black pepper isolates produced sexual stages on culture medium. Based on the growth characteristics on carrot agar, L/B ratio and pedicel length of the sporangium all the black pepper isolates of p. palmivora obtained in the present investigation can be placed in MFI or MF2 or MF3 (Griffin, 1977) or group 1 or 11 (zentmyer at al. 1977) due to the overlapping of chracteristics described for them. None of the weed plants growing in and around the pepper gardens was found to be attacked by Phytophthora species. But five economically important plants viz., arecanut, rubber, cocoa, coconut and cardamom were found to be infected by Phytophthora species. The Phytophthora species from these hosts showed close similarity with P. palmivora isolates from pepper and were identified as P. palmivora. All these isolates of P. palmivora can be placed in MFI or MF2 or MF3 (Griffin, 1977) or group 1 or 11 (zentmyer et al. 1977). The cross inoculation studies with the P. palmivora isolates from different hosts yielded successful results. This indicated that arecanut, rubber, cocoa, coconut and cardamom can serve as collateral hosts of P. palmivora infecting pepper. The sporangia produced by the P. palmivora isolates on cross inoculation showed considerable variations in their size and in few cases shape. These variations made identification directly from the host misleading.
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    ThesisItemOpen Access
    Quick wilt disease of pepper-II: techniques for screening pepper varieties against quick wilt disease caused by Phytophthora palmivora(Butler) butler
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 1982) Vilasini, T N; KAU; Abi Cheeran
    The present study on the quick wilt disease of pepper (Piper nigrum Lin.) was conducted at the College of Horticulture, Vellanikkara. The objective of this study is to find out a rapid and perfect technique to screen large number of Piper types (both open polinatede and hybrid seedlings) against Phytophthora palmivora (Sutler) Butler, the quick wilt (foot rot) organism of black pepper. P. palmivora is capable of producing phytotoxin in vitro. The leaves of P. nigrum assayed with the propagule-free dialysed culture filtrate of P. palmivora, produced necrotic symptoms typical of the natural infection. Five liquid media were tested for production of toxic metabolite by the pathogen. Out of this, Richards + yeast extract broth was found to be the best medium followed by potato dextrose broth which is on par with thiamine enriched synthetic liquid medium for Phytophthora. Seventeen p. nigrum types (open pollinated, hybrid and panniyur-1) were screened against P. palmivora. Three different plant parts namely, leaves (both detached and undetached), stem cuttings and roots were inoculated with viable pathogen and bio-assayed with propagule-free dialysed culture filtrate. The enoculation of the pathogen and administration of propagule-free dialysed culture filtrate on the leaves of potted pepper plants and detached leaves showed the same symptom expression as that of the natural infection of the pathogen. All the pepper types tested were found highly susceptible to leaf infection. Undetached leaves were found better to study the resistance of pepper plants to the disease, due to slow and steady development of symptom on inoculation with the pathogen. Stem cuttings of all the P. nigrum types were inoculated with zoospore suspension and bio-assayed with propagule-free dialysed culture filtrate. The lesion development in both cases were typio of the natural infection of the pathogen. All the pepper types tasted for the stem reaction showed no significant difference between the types, with respect to the symptom expression. The roots of cuttings were inoculated with zoospore suspension and assayed with propagule-free dialysed culture filtrates. In all the pepper types tested by both methods, the entire root system were found decayed within three days after the administration of culture filtrate and within five days on inoculation with zoospore suspension. All the seventeen P. nigrum types tested were found highly susceptible to root infection.