Browsing by Author "Ravindran, P.N."
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Item Chlorophyll stability index as an aid in screening for heat tolerance in cocoa (Theobroma cacao L.)(2007-02-08) Ravindran, P.N.; Menon, M.A.Item Controlled crossing technique in black pepper (Piper nigrum L.)(2007-02-08) Ravindran, P.N.; Nair, M.K.; Mathew, P.A.The flowering in pepper coincides with the South-West monsoon and the continuous rain makes crossing work very difficult under field conditions. The chance of extraneous pollen contamination through rain water also is very high, since in pepper, pollination is aided by rain water. In order to overcome the above limitations, a crossing technique has been developed. The technique consists of inducing rooting in productive laterals and isolating the rooted laterals in earthern pots. The isolated plants are then transferred to indoor before flowering initiates. Pollination could be done either by exploiting the protogynous condition present in pepper, or by emasculating the female parent in isolation. Pollination is carried out by applying an aqueous suspension of pollen to the receptive stigma by brush. The advantages of the technique are that all operations are carried out under controlled conditions and that the hybrid nature of the seeds obtained can be assured. It is also possible to carry out the crossing work throughout the year, as the isolated laterals flower continuously under irrigation.Item Cytology of coconut(2007-02-08) Thankamma Pillai, P.K.; Vijayakumar, G.; Ravindran, P.N.The chromosome number in coconut is 2n=32. Karyomorphological studies show light differences between Tall and Dwarf varieties. Meiosis was generally regular ,n Tall cultivars and in hybrids between Tall and Dwarf, while several irregularities have been reported in the Dwarf and semi-tall cultivars. Pollen fertility is very high in Tails and hybrids as compared to that in Dwarfs and semi-tails. Meiotic irregularities are commonly met within the spicata palms and these are believed to have originated from Tails. Free nuclear division has been reported in coconut milk. C-mitosis leading to high ploidy level and several chromosome abnormalities occur in developing endosperm. In Philippines makapuno nuts, the endosperm development is very abnormal. An inverse relationship between ploidy level and oil content has been also observed by some authors. The two existing views on the origin of Dwarfs from Tails, namely, mutant origin or by continuous inbreeding, are presented. Another possibility that both Tails and Dwarfs might have had a common origin in a single ancestral form has been proposed.Item Flowering, pollination and pod setting in cacao(2007-02) Ravindran, P.N.This study was undertaken in 8-year old ' Forastero ' cocoa (Theo-broma cacao) mix-planted with arecanut palms (Areca catechu) of the same age. The crop is irrigated during the dry months (December-May). The observations on flowering and pod setting were recorded in ten trees, and in each tree, observations were limited to the main trunk, and the figures later transformed to give flower production and fruit set per meter of the main trunk. Natural pollination was studied by randomly collecting 25 flowers daily (int he afternoon) and observing for the presence of pollen grains under the microscope. Efficiency of various pollination methods were studied using fully cross compatible trees. Monthly flower production and fruit setting varied from tree to tree. The peak period of flowering was in May, and the peak period of fruit setting was in March and October. Fruit set was generally more during the dry months from December to June, and very low or absent during July-September. The mean annual fruit set was only 3.0% and out of this only about one fourth reached maturity. Pollination study showed that 28.2% flowers got pollinated under field conditions, while only about 8% of this was successfully pollinated (i.e. having sufficient number of pollen grains for fertilizing majority of ovules present in the ovary). The maximum successful pollination was in March (11%) and the minimum was in December (4.4%). Pollination trials indicated that pollinating on the style gave maximum setting (82%), while pollinating on the stigma alone gave 66.5% setting. The results are discussed in the light of available information.Item In Vitro Germination and Growth of Cacao Pollen(2007-02) Ravindran, P.N.This paper deals with pollen germination, pollen tube growth and pollen tube mitosis in cacao (Theobroma cacao L.). Good pollen germination and growth were obtained in a medium containing 15 % sucrose, 100 ppm boric acid, and 100 ppm calcium nitrate. Boron or calcium was necessary for proper pollen germination and tube growth, and both, if present, enhanced tube growth considerably. No pollen germination was observed at low temperatures (10°C), and maximum germination and tube growth were obtained at 35°C. Further increase in temperature to 40°C affected adversely both germination and tube growth. Pollen tube mitosis began within 2% hr of the initiation of pollen germination, and completed in 2-J hr. Pollen tube mitosis was normal in the cultivars studied.Item Influence of Specific Gravity of Seeds on Early Seedling Growth and Development in Cacao(2007-02) Ravindran, P.N.Item Journal of Plantation Crops : Volume 18 (Supplement) : Proceedings of the Eighth Symposium on Plantation Crops (Placrosym VIII, 1988)(2007-02) Prem Kumar, T.; Sarma, Y.R.; Ravindran, P.N.; Madhusoodanan, K.J.Item Laboratory screening of cocoa genotypes for drought tolerance(2007-02) Ravindran, P.N.Item Mass Pedigree Selection in Arecanut (Arecacatechu L). A Case History on the Application of the Method in a Perennial Tree Crop(2007-02) Ravindran, P.N.; Bavappa, K.V.A.; Pillai, R.S.N.; Ramachander, P.R.; Nair, M.K.; Nair, B.P.; Vijayakumar, K.This paper deals with the results of a mass pedigree selection experiment carried out in the South Kanara cultivar of arecanut. The data collected from the experiment has been utilised for various genetical studies, such as correlated responses, genotypic and phenotypic correlations, path coefficient analysis, heritability, and genetic gain achieved through selection. The results of these analysis are presented and discussed.Item Nuclear Behaviour in the Sterile Pollen of Vanilla planifolia (Andrews)(2007-02) Ravindran, P.N.Vanilla planifolia (Andrews) (Syn. V. fragrans (Salisb.) Ames.) is the source of commercial vanillin, one of the important spices in use. Inspite of its economic importance very little is known about this plant. During the course of a study of pollen biology and cytology some interesting observations were made on the nuclear behaviour in the ungerminated-sterile-pollen grains of Vanilla. The present paper deals with this nuclear division and chromosome behaviour.Item Pepper Varieties(2007-02) Ravindran, P.N.; Nair, M.K.Item Proceedings of the 8th symposium on plantation crops(1988) Prem Kumar, T.; Sarma, Y.R.; Ravindran, P.N.; Madhusoodanan, K.J.Item Quality Evaluation of Black Pepper Cultivars(1983) Kaliannan Raju; Ravindran, P.N.; Nair, M.K.Item Satellite Specific Gravity Selection Of Seeds In Cocoa And Cashew(1982) Ravindran, P.N.; Menon, M.A.This paper gives the results of a trial conducted to study the impact of specific gravity selection of seeds on germination and seedling vigour. Seeds of cocoa and cashew were classified into different specific gravity groups using a water-sugar system. The seeds from each group was studied for their performance with respect to germination, shoot and root growth, leaf production and dry matter accumulation. Seeds of higher specific gravity gave significantly earlier and higher germination in cashew and better seedling growth and dry matter production in cocoa and cashew. In cashew a vigour index could be calculated based on germination rate and period required for germination. Seed specific gravity is found to be a convenient practical criterion for assessing seed vigour. Elimination of the lower specific gravity groups can enhance the speed and rate of germination as well as ensure vigorous seedlings.Item Seed Germination Studies in Black Pepper(1985) Ravindran, P.N.; Muneer, V.M.; Nair, M.K.Item Specific Gravity of Seeds as a Mass Selection Criterian in Cashew(1984) Menon, M.A.; Ravindran, P.N.; Nair, B.P.Item Tissue Culture Of Pepper And Tree Spices: Potential, Priorities And Applications(1988) Nair, M.K.; Ravindran, P.N.The paper highlights the problems in the propagation and improvement of pepper and tree spices and the potentialities offered by the tissue and cell culture; technology in solving some of these problems. In pepper, tissue culture will be useful in meeting the expected demand for rooted cuttings of improved lines during the rehabilitation and developmental programmes visualized for the future. It will be especially useful in accelerating the screening process against pathogens like Phytophthorapalmivora and nematodes. In nutmeg the tissue culturing of elite female trees will be useful in overcoming the dioecy problem as well as in the multiplication of elite lines. Tissue culture technique will be useful in the maintenance of germplasm of pepper and tree spices, in inducing more variability for breeding purposes, in the production of pure lines by anther culture and in the incorporation of new genetic characters through protoplast fusion.Item Variability in Black Pepper Cultivar Karimunda(1985) Ratnambal, M.J.; Nair, M.K.; Ravindran, P.N.