Browsing by Author "Raji, P"

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Analysis of pathotypic variability of Xanthomonas oryzae pv.oryzae, the bacterial blight pathogen of rice and identification of new sources of resistance
(Department of Plant Pathology, College of Agriculture, Vellanikkara, 2023-05-11) Aparna, V S.; Raji, P
Bacterial blight of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is becoming a major production constraint worldwide. In India, the disease is causing considerable yield loss in all rice producing states. In Kerala, the disease is appearing in an epidemic form in recent years in Palakkad, Thrissur and Alappuzha districts. Host plant resistance offers a viable option for the management of the disease. Understanding the pathogen population prevailing in a geographical area is essential for the development of varieties having broad spectrum resistance. The present study was undertaken to analyse the pathotypic variability of Xoo in major rice growing areas of Kerala and to identify new sources of resistance.
Cyclea peltata - a new host of phytophthora palmivora (butler) butler
(Kerala Agricultural University, 1996) Estelitta, S; Sukumara Varma, A; Vilasini, T N; Vimi Louis; Raji, P
Effect of plant protection chemicals on bradyrhizobwm in cowpea (Vigna unguiculata (L) walp)
(Kerala Agricultural University, 1996) Raji, P; Rajendran Filial, M V
Effect of selected plant protection chemicals were tested on Bradyrhizobium both in the laboratory and in the field. The fungicides Thiram, Bordeaux mixture and Fytolan showed inhibition of the bacteria under in vitro conditions. These fungicides caused an initial reduction in rhizosphere population of Bradyrhizobium in the field. But later a gradual increase in the bacterial count was noticed. The fungicide Carbendazim and insecticides Carbofuran, Phorate and HCH showed no inhibition of Bradyrhizobium under laboratory and field conditions. Combinations of all the three insecticides with Thiram, Bordeaux mixture and Fytolan showed inhibition of the bacteria in in vitro. The rhizosphere bacterial population showed an initial reduction when these were applied in the soil.
Effect of selected plant protection chemicals on the beneficial microorganisms in cowpea rhizosphere
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 1995) Raji, P; Rajendran Pillai, M V
A study was conducted at the College of Horticulture, Vellanikkara, during 1992 – 94, on the effect of selected plant protection chemicals on beneficial microorganisms in cowpea rhizosphere. Four fungicides, three insecticides and their combinations were tested in vitro as well as in the field. The tolerance levels of Azospirillum and Bradyrhizobium to different doses of these chemicals were also tested. The fungicide Thiram caused inhibition of Azospirillum in vitro. The adverse effect of Thiram on rhizosphere population of Azospirillum was seen only during initial days after application. The growth performance of cowpea plants were not affected adversely. The fungicides, Carbendazim, Bordeaux mixture and Fytolan and insecticides Carbofuran, Phorate and HCH at their recommended doses did not cause inhibition of Azospirillum in vitro and did not reduce the rhizosphere population of Azospirillum. The growth performance of cowpea plants was also not affected adversely by these fungicides and insecticides. The combinations of insecticides with Thiram caused inhibition of Azospirillum under in vitro conditions and caused reduction in rhizosphere population of the bacteria initially. But no adverse effect on growth of cowpea plant was noticed. Bradyrhizobium was inhibited by the fungicides, Thiram, Bordeaux mixture and Fytolan in vitro. The rhizosphere population of Bradyrhizobium also showed reduction initially. The growth performance of plants was not affected adversely. The number of nodules showed significant reduction. No reduction in nitrogen content was noticed. Carbendazim and insecticides Carbofuran, Phorate and HCH did not show inhibition of Bradyrhizobium in in vitro. The rhizosphere population and growth of cowpea plants were also not affected adversely by these chemicals. Under in vitro conditions the combination of insecticides with Thiram, Bordeaux mixture and Fytolan caused inhibition of Bradyrhizobium. The rhizosphere population showed reduction initially, later on it was increased. The combination of insecticides with Carbendazium did not inhibit the growth of Bradyrhizobium under in vitro conditions and also in the rhizosphere. The treatment combinations did not affect the growth of cowpea plants in the field adversely. The tolerance levels of Azospirillum and Bradyrhizobium to different doses of fungicides and insecticides were also tested. The fungicides Carbendazim, Bordeaux mixture and Fytolan were not inhibitory to Azospirillum, even their highest doses of 0.15, 3.0 and 0.5 per cent respectively. Similarly, the insecticides Carbofuran, phorate and HCH were also not inhibitory to Azospirillum at their highest doses tested. The fungicide Thiram caused inhibition of Azospirillum even at the lowest dose of 0.05 per cent. Bradyrhizobium was inhibited by Thiram and Fytolan even at their lowest doses of 0.05 and 0.1 per cent respectively. Bordeaux mixture 0.25 per cent did not cause inhibition, but the higher doses caused inhibition. Carbendazim and insecticides Carbofuran, Phorate and HCH did not inhibit the growth of Bradyrhizobium in all the five doses tested.
Identification and management of mycoflora associated with grain discolouration of rice (oryza sativa L.)
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2018) Aswathi, M S; Raji, P
Influence of new planting geometry-paired row planting on incidence of diseases in rice
(Department of Plant Pathology, College of Agriculture, Vellanikkara, 2023-05-11) Geethika, T V; Raji, P
Influence of VAM inoculation on nutrient uptake, growth, yield and bacterial wilt incidence in tomato (Lycopersicon esculentum Mill.)
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2002) Raji, P; Sukumara Varma, A
New leaf blight of garcinia cambogia desr.
(Kerala Agricultural University, 1996) Vilasini, T N; Estelitta, S; Rajendran Pillai, M V; Nair, P V; Raji, P