Browsing by Author "Rohini Iyer"

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    Beneficial microbes in the nutrition of coconut
    (2007-02-08) George V. Thomas; Rohini Iyer; Bopaiah, B.M.
    The association of beneficial micro-organisms such as nitrogen fixing bacteria, vesicular-arbus-cular mycorrhiza) (VAM) fungi and phosphate solubilisers with the roots and rhizosphere of coconut has been well established. The non-symbiotic Beijerinckia and associative symbiotic Azospirillum are the predominant nitrogen fixing bacteria associated with coconut. The green manure/cover leguime-Rhizobium association can also contribute substantial quantities of biologically fixed nitrogen in the basins and interspaces of coconut. The palm forms symbiotic association with VAM fungi belonging to the four genera viz., Glomus, Gigaspora, Sclerocystis and Acaulospora. Bacteria and fungi capable of solubilising insoluble phosphates are also found in large numbers in rhizosphere of coconut. The research work carried out on beneficial microbes associated with coconut is reviewed and the future areas of research outlined.
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    Bud rot disease An overview
    (2010) Rasmi, A.R.; Rohini Iyer
    Bud rot is a fatal disease of the coconut palm, characterized by the rotting of the terminal bud and surrounding tissues. Even though it affects palms of all ages, young palms in low and moist situations are more susceptible to the disease. Incidence of the disease has been reported from almost all coconut growing countries of the world.
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    Characterization of Phytophthora palmivora isolates inciting bud rot and nut rot in coconut
    (2010) Rasmi, A.R.; Rohini Iyer
    Cultural and morphological characters of 35 isolates of the Phytophthora palmivora collected from rotting bud and nut of coconut were characterized. Basically the colonies were stellate or striate type. Rate of growth in carrot agar varied significantly among the isolates. Rate of growth was fast in Pp22 and Pp23 and slow in isolate Pp14. The sporangia of all the 35 isolates were found to be caducous and were shed with short, broad and occluded pedicel. All isolates of Phytophthora collected in the present study were found to be heterothallic and were of A2 mating type which produced oospores when paired with A1 isolates. Oospore formation in all isolates was noticed only after 15 days of pairing with an A1 isolate. From the above characteristics, all the 35 isolates were confirmed as Phytophthora palmivora Butl. Maximum growth of both bud rot and nut fall isolates of P. palmivora were observed at pH 6.5 (Mean dry weight, 62.36 mg). A temperature range of 25 and 270C supported maximum growth in both nut and bud rot isolates. Among organic Nitrogen sources, glutamine showed maximum dry weight of mycelium both in case of nut fall (58.27 mg) and bud rot isolates (57.00 mg) followed by those supplemented with L-asparagine.
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    Coconut
    (Naya Udyog, Kolkata., 2006-01) Rajagopal, V.; Parthasarathy, V.A.; Naresh Kumar, S.; Reddy, D.V.S.; Rohini Iyer
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    Coconut Recipes Around the World
    (1991) Rohini Iyer; Thamban, P.K.
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    Coconut: Maladies and Remedies
    (2018) Rohini Iyer; Gunasekharan, M.; Vinayaka Hegde
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    Comparative developmental studies of two fungi forming Vesicular Arbuscular association with ginger and black pepper
    (2007-02-08) Manju Philip; Rohini Iyer
    Two VA mycorrhizal fungi viz: Glomus versiforme, an endophyte associated with black pepper, and G. multicaule, associated with ginger were inoculated in sorghum and in their respective native hosts to study and compare development in these hosts. In case of G. versiforme inoculated in black pepper and sorghum, hyphae, arbuscules and vesicles were produced on both hosts. However, there was delay in the appearance of vesicles in the case of sorghum. Developmental studies of G. multicaule in sorghum and ginger showed that the time of appearance of arbuscules and vesicles were similar in both hosts. However, the unusual appearance of vesicles in the stelar region was, confined to ginger only.
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    Crow - Pheasant and Red Palm Weevil
    (2004-05) Ponnamma, K.N.; Rohini Iyer; Raidu, B.T.; Leena, S.; Sujatha, A.
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    Effect of fertiliser levels on Vesicular Arbuscular Mycorrhiza colonisation in cardamom
    (2007-02-08) Rohini Iyer; Kalpana Sastry, R.; Korikanthimath, V.S.
    Roots of cardamom plants growing in experimental plots with three fertiliser levels were examined twice once before and once after the South-west monsoon. Samples revealed the presence of the following three spp. of VAM fungi: Glomus macrocarpa, G. fasciculatum and Gigaspora coralloidea. Percent colonisation in roots varied from 40-100 per cent in pre-monsoon samples and 63-94 per cent in post-monsoon samples. Infection grading varied from 4.5 to 76.0 in pre-monsoon and 30.0 to 77.0 in post monsoon samples. Results showed that increasing doses of fertiliser tended to decrease the intensity and incidence of the VAM population in soil and roots.
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    Effect of Gliocladium virens, Trichoderma sp. and organic amendments on the inoculum potential of Thielaviopsis paradoxa in soil.
    (2007-02-08) Ramanujam, B.; Nambiar, K.K.N.; Rohini Iyer
    The efficacy of four antagonistic fungi and two organic amendments in inhibiting the pathogen of coconut stem bleeding disease (T.paradoxa) in soil was studied using pot experiments. Among the nine treatments tested, Gliocladlum virens inoculum @ 10.0g/pot + neem cake (50g/pot) + FYM (500g/pot) showed maximum reduction in T.paradoxa population (50.6%). Trichoderma harzlanum, T. viride and T. hamatum, showed comparatively lesser reductions in T. paradoxa population. (31.3,25.3 and 21.9% respectively). Neem cake + FYM alone (@ 50g & 500g/pot respectively) showed the feast reduction In T. paradoxa population (6.1%). Among the four antagonistic fungi tested, maximum post-treatment populations were observed with T. harzlanum (334.67 and 406.67x104 cfu/g for the doses of 5 and 10g/pot respectively), followed by the populations of G.virens (66.06 and 82.6 x 104cfu/g for the doses of 5 and 10g/pot respectively). Soils amended with neem cake + FYM showed Increased levels of native populations of G. virens (0.0262 x 104 cfu/g) and 7: harzlanum (3.8187 x 104 cfu/g) compared to their populations in the un-amended soils (0.0029 and 0.0921 x 104 cfu/g respectively).
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    Effect of organic amendments on rhizome rot of ginger
    (2007-02-08) Sadanandan, A.K.; Rohini Iyer
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    Elite coconut seed garden and commercial production of hybrids
    (2007-02-08) Nair, M.K.; Rohini Iyer
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    Emerging trends in the management of bud rot disease of coconut
    (2004-12) Gunasekaran, M.; Moosa, H.; Rasmi, A.R.; Rohini Iyer; Sheenakumari, T.K.
    In recent times there has been a resurgence of bud rot incidence more or less everywhere in the coconut-growing zones. Though application of Bordeaux mixture is very effective, there are practical difficulties in its implementation. Thesc reasons necessitate the formulation of an alternative IDM strategy for bud rot management. For bud rot management to be effective, a sound forecasting model(s) is an essential one. Considering this, attempts were made to develop forecasting models, based on macro and micro temperature, relative humidity (in plains and hilly areas), and rate of survival of the inoculum in endemic areas during off-season. As an alternative to Bordeaux mixture, systemic fungicides were evaluated: Aureofungin - sol (36.4 g I palm)followed by Calixin (21 ml I palm) as stem injection was found effective. The protection offered against bud rot pathogenby these systemic chemicals extended up to 8 weeks, thus safeguarding the palms during vulnerable period. No residues could be detected in nut water and kernal up to six months after application in the case of Calixin. Hence, the systemics can be administered in advance, well before the onset of the monsoon and there is no need-to climb the tree since the chemical can be administered from the ground. An endophytic bacterium (Bacillus amyloliqriefaciens), a fungus (Trichodernia harzianurn) and botanicals (Andrographispaniculata and Lawsonia inerntis) were found very effective against F palmivora. As these botanicals are not compatible with the antagonist, Z harzianurn sequential application of botanicals and Z har:ianlim by maintaining a suitable interval between the applications is suggested. With the use of standardized ex viva varietal screening technique, a tall cultivar, Laccadive Ordinary (LO) and a dwarf cultivar. Ganga Bondam (GB) were identified as bud rot tolerant varieties. Formulating an IDM strategy combining all the above practices, viz., planting resistant / tolerant varieties, bud rot forecasting based on weather parameters. application of systemic fungicides as prophylactic and application of antagonists (bacterium and fungus) and botanicals for long term sustenance of disease suppression is discussed in this paper.
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    Eriophyid Mite
    (2010) Rohini Iyer; Jacob Mathew; Chandrika Mohan; Anitha Kumari, P.; Nair, C.P.R.
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