Browsing by Author "Ravikumar, N."
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Item Cyber extension for transfer of technology in India(2004-12) Arulraj, S.; Ravikumar, N.The Information Technology is being increasingly utilized in the Transfer of Technology process in India during the recent years. CPCRl launched its web site in April 2000 and it is encouraging to note that the web site facilities are being increasingly used by the farming community and other clients. A "user analysis" of email services at CPCRL indicated that farmers from Tamil Nadu, Karnataka and Kerala utilized the services to the maximum extent possible followed by students and entrepreneurs. They used the services mainly for obtaining information on the cultivation details. processing technologies and other institute programmes. Coconut crop continued to be the major focus of the clients queries followed by cocoa and arecanut. Dc~ails on the plan for starting a "Net-work Programme on Cyber Extension in Horticultural Crops" are also indicated in the paper.Item Design of Data Marts for Plantation Crops(2002) Ravikumar, N.; Muralidharan, K.; Sairam, C.V.; Palaniswami, C.; Dhanapal, R.; Arulraj, S.; Anil Rai; Vipin Dubey; Chaturvedi, K.K.Plantation crops occupy a significant position in the agricultural sector and play a significant role in the. Indian economy. To apply the Information Technology tools, it is required to link all the relevant data sets in to a single system. To achieve this objective, the Indian Council of Agricultural Research (ICAR) has launched a mission mode project entitled Integrated National Agricultural Resource Information System (INARIS) involving 14 research institutes. The efficiency of the databases at various centres could be enhanced by providing solutions to customer queries in an integrated manner, for which data marts are to be developed. In this papeG basic concepts of designing of the data marts are applied to the plantation crop sector. Three data marts viz., statistics, agro-techniques and research were identified in the field of plantation crops as a part of Centralized data warehousing of national agricultural resources. Different aspects of data mart design were delineated. The detail and summary levels of data in the data mart were documented. Developing data marts will help to evolve decision support tools in respective area of specialization without much cost involved. Finally, the data warehouse would be built-up by joining the data marts.Item Digital phenotyping of coconut and morphological traits associated with eriophyid mite (Aceria guerroronis Keifer) infestation(2013-12) Arunachalam, V.; Augustine Jerard, B.; Elain Apshara, S.; Jayabose, C.; Subaharan, K.; Ravikumar, N.; Palaniswami, C.Observations were recorded on traits associated with mite infestation related at two stages of button on six different coconut cultivars over three years. Highly significant correlation was found between mite damage score with color or weight of tepal. Step-wise multiple regression of the data analysis showed color of inner tepal as major trait associated with infestation by eriophyid mite. Other traits are ratio of tepal weight to tepal area, per cent of buttons with pink discoloration or with resin, tepals of regular aestivation and gap between fruit and tepal. Digital phenotype data of 83 image files were used to calculate color signature and correlated the same to mite damage score over three years. Red spectral values were found to vary from 14 to 251, green values to 12 to 237 and blue to vary from 5 to 183. Spectral values red max, green max, 3* Red + Green max had high significant negative correlation (>-0.4) with mite damage. Color and firmness of fruits and tepals of three coconut varieties were further analyzed where, fruits and tepals of COD variety showed high red/green (a* value of Hunterlab) >12. Firmness of 3 month old tepal and fruit of Benualim (BGRT) tall variety was (penetrometer reading >38) higher than other varieties.Item Effect of sub lethal dose of insecticides on electrophysiological and behavioral response of Bracon brevicornis Wesmael (Braconidae : Hymenoptera) a parasitoid of coconut black headed caterpillar, Opisina arenosella Walker (Oecophoridae : Lepidoptera)(2012) Kesavan Subaharan; Charles Sahayaraj; Prasad, A.R.; Ravikumar, N.Bracon brevicornis Wesmael (Braconidae : Hymenoptera) is an effective parasitoid against coconut black headed caterpillar, Opisina arenosella Walker (Oecophoridae : Lepidoptera) a major pest on coconut. During outbreaks, chemical insecticides and bioagents are used in tandem to manage O. arenosella. Traditionally the impact of pesticides on beneficial arthropods was assessed by determining acute toxicity. In addition to direct mortality caused by insecticides, the sublethal effect on sensory physiology and behavior of parasitoids must be considered for complete analysis of their impact. The present study aims to investigate the impact of sub lethal dose of insecticides on B. brevicornis. In olfactory assay, the starved parasitoids oriented to food source, whilst the fed parasitoids responded more to host volatiles. In electrophysiological assay, the antennal responses of B. brevicomis to host volatiles were higher in female. Among the volatiles tested, the host frass and host haemolymph was most preferred by both sexes. Exposure of B. brevicornis to sublethal dose of imidacloprid, malathion and carbaryl (LD20) altered the orientation of B. brevicornis to host volatiles.Item Electrohysiological and behavioral response of Goniozus nephantidis Muesbeck, to plant and host volatiles(2011) Subaharan, K.; Ravikumar, N.; Prasad, A.R.Experience of parasitoids with host and host related products have effects on their behavior. Learning can be induced by conditioning parasitoids at various stages i.e. pre imaginal or imaginal (after eclosion). Here we studied the volatiles from damaged, undamaged coconut leaflets and Opisina arenosella larval frass that cause electrphysiological and behavioural response in the bethylid parasitoid Goniozus nephantidis. The possibility of using the host frass for conditioning the parasitoids was explored. The damaged coconut leaflets released cyclopentanone, butanol, and alpha pinene and these compounds were absent in undamaged leaflets. Z-3 hexenol, a green leaf volatile was trapped form both damaged and undamaged plants. Alpha pinene released form undamaged leaflets caused the highest electroantennogram (EAG) peak amplitude (O.330mV) in female antennae. This was followed by cyclopentanone (O.30mV), hexanone (O.29mV) and hexanal (O.29mV) which were all at par. G nephantidis reared on Corcyra cephalonica conditioned with the larval frass of O. arenosellla when provided a choice preferred to parasitize O. arenosella as compared to C. cephalonica. Conditioned parasitoids when released in the field caused 59 per cent reduction in larval population per leaflet as compared to 29 per cent reduction by unconditioned parasitoids two months after release. Conditioning of G nephalliidis with odors of O. arenosella will aid to enhance the host searching ability of the parasitoids that were reared on C. cephalonica.Item Tracking the locomotion of coconut black headed caterpillar, Opisina arenosella and its parasatoid, Goniozus nephantidis(Indian Society for Plantation Crops, 2008) Ravikumar, N.; Janakiraman, T.N.; Hemalatha Thiagarajan; Subaharan, K.Item Video conferencing for organising research-extension - farmer interface programmes(2013-11) Thamban, C.; Muralidharan, K.; Ravikumar, N.; Amarnath, C.H.