Browsing by Author "Regi J. Thomas"
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Item Carbon Sequestration and Coconut Farming: A Sustainable Path Forward(2024-12-01) Mayalekshmi; Abdul Haris, A; Shareefa, M.; Regi J. ThomasItem Coconut varieties tolerant to root (wilt) disease(2014) Regi J. Thomas; Shareefa, M.; Krishnakumar, V.; Chowdappa, P.Item Domestic quarantine umbrella to prevent spread of root (wilt) disease to be strengthened(2015-08) Regi J. Thomas; Joseph Rajkumar, A.; Shareefa, M.; Merin BabuItem Flowering and pollination biology in coconut(2013) Regi J. Thomas; Josephrajkumar, A.Coconut is a seed propagated crop and knowledge on its flowering and pollination biology will be of significance for optimizing the pollination techniques and also to design efficient conservation strategies in gene banks. Coconut palm is monoecious, with inflorescence bearing both staminate and pistillate flowers. The male flowers are the first to open, beginning at the top of each spikelet and proceeding towards the base. The male phase is followed by female phase and in tall varieties there is a gap between these two phases within the same inflorescence. Although both wind and insects bring about pollination, insect pollination is more predominant. Strategies for employing honey bee colonies in coconut plantations and seed gardens for enhancing pollination and fruit set are discussed. Future lines of work with regard to pollination biology aiming increasing fruit set in coconut seed gardens are also pointed out.Item Freak coconut palms(2015-12) Gayathri, T.; Regi J. Thomas; Shareefa, M.Item Hybrids and Hybridization techniques in coconut(2011-09) Regi J. Thomas; Shareefa, M.; Jacob, P.M.Item Identification of expressed resistance gene analog sequences in coconut leaf transcriptome and their evolutionary analysis(2015) Rajesh, M.K.; Rachana, K.E.; Naganeeswaran Sudalaimuthu Asari; Shafeeq Rahman; Regi J. Thomas; Shareefa, M.; Merin Babu; Anitha KarunCoconut, an important crop of the tropics and subtropics, is susceptible to a variety of diseases and enhancing disease resistance has been the major goal of coconut breeding programs all over the world. Information on the presence and distribution of disease resistance (R) genes, which play a primary role in the detection of pathogens and the initiation of specific plant defenses, is scarce in coconut. In this study, RNA-Seq was used to generate the transcriptome of leaf samples of coconut root (wilt) disease-resistant cultivar Chowghat Green Dwarf. Comprehensive bioinformatics analysis identified 243 resistance gene analog (RGA) sequences, comprising 6 classes of RGAs. Domain and conserved motif predictions of clusters were performed to analyze the architectural diversity. Phylogenetic analysis of deduced amino acid sequences revealed that coconut NBS-LRR type RGAs were classified into distinct groups based on the presence of TIR or CC motifs in the N-terminal regions. Furthermore, qRT-PCR analysis validated the expression of randomly selected NBS-LRR type RGAs. The results of this study provide a sequence resource for development of RGA-tagged markers in coconut, which would aid mapping of disease-resistant candidate genes. In addition, we hope that this study will provide a genomic framework for isolation of additional RGAs in coconut via comparative genomics and also contribute to the deciphering of mode of evolution of RGAs in Arecaceae.Item Laying out of Demonstration Plots for integrated management of coconut root (wilt) disease in Tenkasi district(2024-12-01) Josephrajkumar, A.; Regi J. Thomas; Indhuja, S.; Merin Babu; Anes, K.M.; Jilu V. Sajan; Shareefa, M.Item Production of Neera(2013-05) Sunil A. Nair; Mejosh Jose; Regi J. Thomas; Nair, R.V.Item Production of Neera and its value addition(2009-05) Sunil A. Nair; Mejosh Jose; Regi J. Thomas; Nair, R.V.Item Strategy for planting material production in coconut(2011-07) Regi J. Thomas; Shareefa, M.; Jacob, P.M.; Nair, R.V.Item Studies on fruit set in coconut upon artificial pollination in various cross combinations(2012-03) Regi J. Thomas; Nair, R.V.; Mathews, C.; Ajith Kumar, R.; Sasikala, M.; Nampoothiri, C.K.Studies on fruit set in coconut have important implications in nut yield. A detailed study was carried out to determine the fruit set in coconut as influenced by variety, cross combination, climatic variables such as rainfall, temperature and relative humidity. Artificial pollination was carried out on selected parental palms of West Coast Tall (WCT), Chowghat Green Dwarf (CGD) and Chowghat Orange Dwarf (COD) in farmer’s plots over a period of five years commencing from 1996-2000. The various cross combinations tried among the three varieties, viz., WCT, CGD and COD were three selfing, two inter se and three crosses. The mean fruit set for the different cross combinations was 24.67%. The maximum fruit set (39.54%) was in COD (self) followed by WCT (self) and COD x WCT, and minimum in CGD x WCT (19.16%) indicating that COD variety as a female parent gave significantly higher fruit set compared to other varieties. Generally, the varieties WCT and CGD under selfing gave a higher fruit set (27.43 and 24.65%) when compared to inter se (21.63 and 21.22%). Fruit set was maximum (28.73%) during March and minimum (18.80%) during May but the year-to-year variation was not significant. The bimonthly average relative humidity (%), number of rainy days and rainfall (cm) had a significant negative correlation (-0.504, -0.428, -0.395, respectively) with fruit set. Studies also revealed that there was a significant reduction in fruit set to the tune of 35%, when climatic conditions are not favourable. The present investigations revealed that fruit set in coconut vary significantly due to genotype, cross combination and climatic variables.Item Studies on genetic uniformity of Chowghat Green Dwarf and Malayan Green Dwarf varieties of coconut using molecular and morphometric methods(2015-08) Regi J. Thomas; Rajesh, M.K.; Jacob, P.M.; Mejosh Jose; Nair, R.V.Two coconut varieties viz., Chowghat Green Dwarf (CGD) and Malayan Green Dwarf (MGD) were subjected to morphometric and molecular studies to assess their genetic uniformity. Since both these varieties possess traits for high yield and resistance to root (wilt) disease, they have already been released for cultivation in the root (wilt) disease prevalent tracts. Forty two CGD palms from ‘disease hotspots’ were analyzed using 43 simple sequence repeat (SSR) primers. Monomorphic bands were detected in all the CGD samples with 41 primers, which is an indication of its genetic uniformity. A single CGD palm showed polymorphism with two SSR primers. Forty eight MGD palms were analyzed using 24 SSR primers. The MGD palms clustered at 62 per cent similarity. Analysis of morphological and fruit component characters of CGD and MGD population revealed that both the populations were phenotypically uniform. Breeding behaviour studies revealed that both CGD and MGD were predominantly self pollinated, like other dwarf varieties of coconut. There was complete overlapping of male and female phases in almost 96 per cent of CGD palms. Almost 100 per cent self-pollination was ensured in these palms as male phase prolonged even after completion of female phase. However, only 60 per cent of the MGD palms showed complete overlapping and in the remaining 40 per cent palms, there was only partial overlapping of male and female phases. From the present study, it is inferred that breeding behavior and genetic uniformity could be highly correlated in coconut. Collection of seed nuts preferably from mother palms with overlapping of male and female phases could possibly ensure production of true to type progenies in dwarf varieties of coconut. Present study also indicated that molecular markers like SSRs may be used to identify genetically pure mother palms for varietal improvement programmes in coconut.Item Studies on vivipary in dwarf coconut cultivars(2014-12) Shareefa, M.; Regi J. Thomas; Nampoothiri, C.K.; Anitha KarunVivipary is a problem in some dwarf varieties of coconut as their seed nuts show low germination compared to Talls. An experiment was carried out to study the extent of vivipary in dwarf coconut varieties (MGD, MYD, MOD and CGD) with WCT as control. Observations on nut traits like shape, colour, length, weight and water content of the seed nut, thickness, weight and polyphenol content of the husk, length and weight of embryo, TSS of nut water were recorded from 10-, 11- and 12-month-old nuts of each variety. Observations were also recorded at bimonthly intervals during November 2011-September 2012. None of the ten-month-old seed nut exhibited vivipary. However, few 11th old MOD nuts (3%) harvested during November showed vivipary. The results showed that the extent of vivipary was highest during September and least during January. Among the varieties, MYD exhibited maximum vivipary (24%) followed by MOD and MGD (16%) and the least was in WCT (0.6%). Vivipary was negatively correlated with various nut characters, husk thickness and weight. However, prevailing climatic conditions like amount of rainfall, number of rainy days and relative humidity during the preceding 30-day of harvest had significant positive correlation with vivipary. It is suggested that vivipary in dwarf varieties can be avoided by harvesting the seed nuts at the proper stage.Item Varieties resistant to root (wilt) disease of coconut(2013-07) Regi J. Thomas; Shareefa, M.; Nair, R.V.