1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Crops loss caused by root-knot nematode infesting coleus parviflours and its control(Department of Entomology, College of Agriculture, Vellayani, 1988) Sosamma, P; Ravindran Nair, K KCrop loss caused by the root-knot nematode infesting Coleus parviflorus and its control was studied in a pot culture experiment and a field experiment in the Department of Entomology, College of Agriculture, Vellayani, Trivandrum, during August to December, 1986. The number of leaves, shoot length, fresh shoot weight and weight of tubers obtained were less in inoculated plants than in control. The yield and growth parameters showed an negative correlation with the population of nematodes. A high positive correlation was noticed between the tuber weight and the number of leaves and shoot weight of coleus. The shoot length did not influence the tuber yield significantly. Roots showed profuse galling by the second month. Rotting of roots was observed by the third month, and at harvest, no healthy root was present in infected plants. Tubers when stored developed dark patches on the suface of galls and these spread inwards covering the whole of the internal tissues within nine days, and by the twelfth day the internal contents had turned into a dark brown watery liquid with a bad odour. The peel of the tubers did not show rotting. The nature of rot indicated the involvement of secondary organisms like bacterial and fungi. Histopathological studies showed that the nematodes were lodged in the cortex with head in the stellar region of the root. One month after inoculation, quadrangular giant cells (four in number) were observed in roots. There was cell proliferation in the stellar region of the infected roots. Alternate arrangement of the xylem and phloem was disturbed, though the central cylinder and cortex could be distinguished. Two months after inoculation the giant cells were seen larger and fewer in number. The cytoplasm of giant cells became granular and aggregated towards the head region of the nematode. Stele could not be easily distinguished from the cortex. The cortex was greatly enlarged due to hypertrophy and hyperplasia of cells. The development of medullary rays and secondary xylem noticed in the normal root could not be distinguished in infected roots. Infected roots showed numerous cavities formed by the disintegration of giant cells, egg masses and adult females by end of the fourth month. Necrosis of tissue was also observed. The xylem and phloem elements were not distinguishable. At five months after inoculation the tissues of the roots were completely rotten. In the field experiment application of nematicides one month after planting preceded by the burning of plant material in the field prior to planting was found better than the other treatments. Carbofuran @ 1 kg a.i./ha was more effective than phorate for the control of the nematode. No residue of carbofuran or phorate could be detected in tubers at harvest. The rotting of tubers obtained from different plots when kept in store indicated the inefficacy of the treatments for giving protection from the nematode and the need for a second application of the nematicide at tuber setting. Hot water treatments of the tubers prior to storage did not reduce the damage.Item Bioecology and management of root-knot nematode Meloidogyne incognita chitwood in kacholam Kaempferia galanga Linn(Department of Entomology, College of Agriculture, Vellayani, 1998) Rajani, T S; Sheela, M SThe biology of root-knot nematode of kachlolam, its histopathological effects on roots and the effect of soil type on the pathogenicity of M. incognito infesting kacholam were studied under pot culture conditions. The effect of soil moisture and pH on the hatching of eggs and survival of larvae were studied in vitro in micro pots. Field trials were carried out to assess the crop loss and to find out a suitable management strategy for the root-knot nematode infesting kacholam. The root-knot nematode, Miincognita took 37 days for the completion of one life cycle in kacholam plants at room temperature of 27 + or - 3 0 C and the mean number of eggs observed per egg mass was 130. In kacholam roots, the nematode mainly infests the xylem vessels. The giant cells were quadrangular in shape and three in number and were observed adjacent to the head of the nematode. Field capacity was the most favourable soil moisture level for the hatching of eggs and survival of larvae of M.incognita. There weas no statistically significant variation in the hatching of eggs and survival of larvae under different soil pH levels ranging from 5 to 7.5. Sandy soil (Entisol) was found to be the best soil type for the multiplication of M. incognita infesting kacholam roots. The biometric characters and yield were reduced with the increase in inoculum levels and a maximum reduction was noticed at 10,000 12 level in all soil types under pot culture conditions. At field conditions, inoculation of 1000 12 per plant resulted in the reduction of number of leaves, rhizome length, root weight and yield per plant and per plot yield to the tune of 43.33,23.71,46.26,63.69 and 43.46 per cent respectively over control plants. Neem cake 200 g/m2, V AM (Glomus fasciculatumy 300 g/m2 inoculum per plant and cabofuran 3.33 g/ m2 were found effective for the management of root-knot nematode, M. incognita infesting kacholam.But neem cake treatment was found to be the best in reducing the soil and root population of nematodes and increasing the plant growth characters (number of leaves, length of rhizome and weight of roots) and yield (rhizome weight per plant and per plot) of kacholam.Item Pathology of experimental pasteurellosis in ducks(Centre of Excellence in Pathology, College of Veterinary and Animal Sciences, Mannuthy, 2009) Pramod, S; Divakaran Nair, NThe present study was undertaken to evaluate the pathological aspects of pasteurellosis in ducks following experimental inoculation by different routes – subcutaneous and intranasal. The haematobiochemical changes associated with the infection were also studied. Body weight changes at weekly intervals, mortality pattern, haematological and biochemical parameters such as total erythrocyte count, total leucocyte count, haemoglobin concentration, differential leucocyte count, total protein, albumin and globulin values estimated at weekly intervals were the parameters used, to study the changes caused by the infection. Gross pathological changes and histopathological changes of heart, liver, lung, kidney, brain, intestine, spleen, caecal tonsils and bursa were also studied. Statistically significant alteration was not observed in body weight. Mean Hb, TEC, PCV, albumin, heterophil and eosinophil percentage values were markedly increased after infection. Correspondingly, the lymphocyte and monocyte counts and the total protein values showed a significant decrease. Acute onset of the disease with sudden mortality was noticed in subcutaneously inoculated birds. Peracute death without any symptoms and lesions was shown by two birds in this group. The peracute pattern of mortality seen in this group was not observed in intranasally inoculated group. But the severity of clinical signs and lesions were more in intranasally inoculated birds. After the first two peracute deaths, symptoms of acute toxaemia such as pyrexia, dullness, depression, inappetence, reluctancy to move, paralysis of limbs and neck and incordination were expressed by the birds before death. The birds died from second day after inoculation onwards revealed an acute haemorrhagic septicaemic picture on all visceral organs. Haemorrhages on epicardium and scattered pin point necrotic foci in the liver, the prominent lesions of fowl cholera, were clearly evident. These lesions were more pronounced in the birds inoculated intranasally with P. multocida, which died on 23rd, 24th and 25th day post- inoculation. The lung and brain lesions were more severe in these birds. Reisolation of P. multocida was carried out from the liver, heart and spleen of all the dead birds except control and survived birds. The present study proved that the route of entry of organism played a significant role in the progression of infection, onset of mortality, number of deaths and symptoms and lesions in fowl cholera outbreaks. The immune suppression due to lymphoid organ damage in fowl cholera make the birds more susceptible to other infections.