Browsing by Author "Geetha, L."
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Item Clonal multiplication of oil palm (Elaeis guineensis Jacq)(2007-02-08) Raju, C.R.; Sajini, K.K.; Balachandran, S.M.; Saji, K.V.; Geetha Maheshan, K.; Rajasekharan, P.E.; Geetha, L.; Bavappa, K.V.A.Five mm long tender leaf explants and leaf base explants taken from 3-year-old seedlings were cultured on defined media supplemented with various auxins and cytokinins. Cultures were incubated in the light. The expaints produced callus from the veins at the cut surface in 2-3 weeks on R medium containing 20 mgl-1 2,4-D and 0.1 mgl"1 BAP. Somatic embryoids developed on lowering the 2,4-D concentration and replacing it with NAA. Bipolar and tripolar embryoids originated as snow-white protuberences from die sub-surface layers of the callus. The process of germination of the somatic embryoids was similar to that of normal zygotic embryos. However, the formation of adventitious roots was enhanced with die addition of 0.01 mgl-1 IBA to the medium.Item Developing a polymerase chain reaction based detection method for coconut root (wilt) phytoplasma(2007) Mayilvaganan, M.; Gunasekaran, M.; Sheenakumari, T.K.; Geetha, L.; Rajeev, G.; Solomon, J.J.; Sasikala, M.Item Electron microscopic evidence on the role of Stephanitis typica (Distant) as vector of coconut root (wilt) disease(1987-12) Mathen, K.; Solomon, J.J.; Rajan, P.; Geetha, L.Item Electron microscopic evidence on the role of Stephanitis typica (Distant) as vector of coconut root (wilt) disease(2007-02-08) Mathen, K.; Solomon, J.J.; Rajan, P.; Geetha, L.Item Mass Production of the Entomopathogen Metarhizium anisopliae in Coconut Water Wasted from Copra Making Industry(2007-02) Dangar, T.K.; Geetha, L.; Jayapal, S.P.; Pillai, G.B.Item Phytoplasma disease of coconut in India - root (wilt) and tatipaka diseases(2004) Solomon, J.J.; Geetha, L.Root (wilt) and Tatipaka diseases in India are caused by phytoplasma. Lethal yellowing disease in Caribbean region, Lethal yellowing like disease in west and east Africa and Coconut stem necrosis in Sumatra and Peninsular Malaysia are phytoplasma induced diseases of coconut in other continents. Root wilt disease in India was first reported from Kerala in 1874. Tatipaka disease was first noticed in Andhra Pradesh after the 1949 cyclone. The progress made on various aspects including history, nature of spread, description of external & internal symptoms, etiology, abiotic factors, biotic agents implicated in transmission of disease, culturing, chemotherapy, screening of coconut germplasm, breeding for disease resistance/tolerance and disease management is detailed.Item Phytoplasmal Diseases(2018) Solomon, J.J.; Vinayaka Hegde; Merin Babu; Geetha, L.Item Studies on spear rot disease of oil palm in Kerala, India I. Establishment of phytoplasma etiology and yellow leaf disease affected arecanut as the source of inoculum(2004-12) Kochu Babu, M.; Ramachandran Nair, K.; Solomon, J.J.; Nambiar, K.K.N.; Geetha, L.Experimental transmission of phytoplasmas (Mycoplasma-like organisms) associated with spear rot disease (SRD) of oil palm in Kerala. India from oil palm to oil palm and yellow leaf disease (YLD) affected arecanut to oil palm was attcmptcd using dodder laurel, Cassytha filiformis L. Positive transmission by symptom reproduction was observed in five oil palm seedlings after 10- I8 months of bridging to SRD-affected oil palm and two out of four oil palm seedlings bridged to YLD affected Areca palm. Electron microscopic detection of phytoplasmas in all the seedlings which have expressed symptoms confirmed the transmission of this disease.Item Studies on the Ultra-Structural Changes in Root (Wilt) Diseased Palms(1993) Solomon, J.J.; Geetha, L.Coconut root (wilt) disease, a debilitating malady is characterized by external symptoms like flaccidity, yellowing and necrosis. Anatomy of the diseased roots revealed alterations in vascular tissues in the form of tylosis of xylem vessels, gummosis and phloem necrosis. In the course of the investigation to detect submicroscopic pafhogen(s) associated with the disease, tissues of submeristem, bases of rudimentary leaves, rachilla of juvenile inflorescence, spear leaf, mature leaf and root tips were studied. The samples examined were from palms of various intensities of disease. The prominent structural changes noticed were an elaboration of the membrane system with unusually large number of cell organelles, presence of paramural bodies and accumulation of electron dense material filling the sieve tube indicating necrotic obliteration of the phloem cells and deposition of callose adjacent to the sieve pores. Disproportionately high number of phytoferritin particles and cuneate crystalline inclusions were the other prominent alterations observed. These structural anomalies in relation to the disease are discussed.Item Transmission of a mycoplasma-like organism from Cocos nucifera with root (wilt) disease to Catharanthus roseus by Cassytha filiformis(1988) Sasikala, M.; Mathen, K.; Govindankutty, M.P.; Solomon, J.J.; Geetha, L.A mycoplasma-like organism (MLO) was successfully transmitted through dodder laurel (Cassytha filiformis) from root (wilt) diseased coconut to periwinkle (Catharanthus roseus) plants. Symptoms caused by the organism in periwinkle were chlofotic spots in the interveinal areas and at vein endings of fully opened leaves, later coalescing into yellow patches, and premature leaf abscission. Light and electron-microscopic examination revealed the presence of MLOs in diseased coconut palms, dodder laurels and periwinkles.Item Ultra-structural studies in establishing the etiology of yellow leaf disease of arecanut and the vector role of the plant hopper proutista moesta (Westwood)(1999) Solomon, J.J.; Ponnamma, K.N.; Rajeev, G.; Geetha, L.