Browsing by Author "Ravindran Nair, K K"

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Crop loss caused by root-knot nematode Meloidogyne incognita Kofoid) infesting Coleus parviflorus and its control
(Department of Entomology, College of Agriculture, Vellayani, 1988) Sosamma, P; Ravindran Nair, K K
Crop loss caused by the root-knot nematode Infesting Coleus parvlflorus 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 a negative correlation with the population of nematodes. A high positive correlation was noticed between tho tuber weight and the number of leaves and shoot weight of coleus. The shoot length did not influence the tuber yield significantly
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 K
Crop 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.
Efficiency of potassium schoenite as a source of potassium to rice
(Kerala Agricultural University, 1979) Alexander, V T; Ramachandran Nair, V; Ravindran Nair, K K
Studies on the population of soil nematodes in relation to certain chemical and biotic factors of soil
(Division of Entomology, Agricultural College and Research Institute, Vellayani, 1969) Ravindran Nair, K K; Mohan Das, N
A total of 40 soil samples were collected and analysed to study the variations in the population of plant parasitic and non parasitic soil nematodes with reference to the chemical and biotic environments existing in soil. The total population of soil nematodes and the population of non-parasitic forms show a positive correlation with the pH of the soil within a range of 4.5-7.4. The parasite population is not correlated with the pH of the soil. There exists no correlation between the soil nematode population on the one hand and organic matter content , total soluble salts, and fungus and bacterial population of the soil on the other.
Use of organic amendments for the control of root-knot nematode In brlnjal
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1986) Kamalakshi Amma, P L; Ravindran Nair, K K
Two field experiments were conducted - one for evaluating oilcakes and another for evaluating organic wastes for the control of the root-knot nematode Meloldogyne incognita infesting brinjal, (These experiments were carried out in the Instructional Farm, College of Agriculture, Vellayani, in an area already infected by root-knot nematode. The experiments were laid out in randomised block design with three replications. In the first experiment there were ten treatments including the control and in the second experiment there were eleven.treatments including the control. Organic amendments were applied to the soil three weeks prior to planting and watering was done during this period for the proper, decomposition of these materials. Results were assessed in terms of yield, growth parameters, gall formation and population of nematode. Results indicated that the nematode population in roots as well as in soil was significantly reduced by the application of oilcakes and organic wastes. It was also observed that the intensity of gall formation on roots was considerably reduced as a result of application of organic amendments. Reduction in the population of the nematode and in the intensity of gall formation in turn resulted in bettor crop stand and increase in yield. (Different methods of application vis. application in the planting pit and broadcasting in the plot did not vary in efficacy.