Faculty of Humanities and Sciences
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Publication Open Access A case study on identification and assessment of postharvest losses of tomato (Lycoperisicon escuentum Mill)(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1992) Rupasinghe, H. P. V; Peiris, C. N; Wijeratnam, R. S. WA study was undertaken to quantify and identify the causes of the postharvest losses of tomato during the Malta season of 1991. In the first phase of the study a suivey was earned out using random samples to collect information on the present system of posthaivest handling of tomato. Four major stages of the posthaivest marketing sequence were identified, namely; fann gate, collection agent, Manning wholesale market (Colombo) and exporter respectively. Loss assessments were conducted at these stages. Tlie survey revealed that pest and diseases such as pod borrer (Heliolhis zea) attack and blight (Altemuiia solani and Pliyiopluliora infestans) are the major contributions for posthaivest losses at the fann gate. Over maturity at hanest, bird attack and losses due to sun scorch were also obseived. Cultivating small extents of land (66% of farmers possess less than half acre) increases the liaircsting interval which resulted in a high percentage of over maturity. Tlie above factors subsequently made considerable losses at the collection agents when soiling the product for transportation. Significant losses were observed al the Manning market due to long distance of transportation with improper handling and transportation. Tlte main problem with exporters was the lack of uniformity of product with respect to maturity and size. Cumulative loss at the Manning wholesale market was obseived to be close to 54%. Contributions to the major causes of loss were as follows; mechanical damage due to over ripening 17.3%, pod borrer attack 23%, blight 4.8% and mechanical damage due to other factors 15%. Tlie cumulative loss and rejections after export quality selection was as high as 96%. Rejects due to non conformity to export specifications with respect to maturity, size and shape were 27.52% and 7.34%, respectively.Publication Open Access Effect of packaging material on the storability of Chillie (Capsicum annum L.) seed in Sri Lanka(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1994) Silva, S. G. R; Peiris, C. NExtracted chillie seed from ripe, desiccated dry pods of cultivar MI 2 of known germination (81.0%), was dried to 9.7%, 5.9% moisture contents, and packed in three different packaging materials: aluminium foil, 500 gauge polythene and woven polypropylene sacks. The seeds were stored at ambient conditions in Pelwehera (30°C, 80% RH), Rahangala (23°C, 79% RH) and in a cold room (20°C 65% RH) in Gannoruwa. Seed germination, field emergence, and seed moisture content of the stored seed were tested at the inception and at 3 month intervals during the 12 month study period. Chillie seed with a low initial moisture content (5.9%) maintained germinability better than seeds with a high moisture content (9.7%) in all locations. Triple laminated aluminium foil was a better packaging material. Polysack packaging displayed free moisture movement from the early stages of the study, in all the locations. Polythene (500 gauge) was better than polysack and similar to aluminum foil when storing low moisture (5.9%) chillie seed for 12 months, at all the locations except in Pelwehera. A cold room condition was the best to store chillie seed without losing its viability below 75% for a period of one year. It could be recommended that these dried, extracted chillie seed from ripe dry pods of cultivar MI 2 packed in aluminium foil or in polythene (500 gauge) be stored in a cold room (20PC, 65% RH) for a long term (12 months).Publication Open Access Identification of cowpea cultivars (Vigna unguiculata (L) Walp) by isoenzyme electrophoresis(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1994) Eeswera, J. P; Peiris, C. NThe differences among cowpea (Vigna unguiculata (L) Walp) cultivars were identified using electrophoretically detected isozymic variability. The enzymes studied in the selected 10 cultivars of cowpea were Diaphorase (DIAP), Phospho Gluco Isomerase (PGI), 6Phospho Gluconate Dehydrogenase (6PGD), Phospho Gluco Mutase (PGM), Esterase (EST), Hexose Kinase (HK) and Glucose Oxalo Acetate Transaminase (GOT). Starch gel electrophoresis was used to analyze extracts prepared from young leaf tissues of seven day old seedlings of each cultivar grown under greenhouse conditions. Three enzymes GOT, HK, and PGM exhibited two patterns, while three different patterns were observed for EST and 6PGD. Phospho Gluco Isomerase showedfour different patterns, and DIAP appeared to be the most polymorphic with eight patterns. Distinct variety specific zymograms were observed for several enzymes. Unique combinations of isozymic variants of two enzyme systems assayed (DIAP and PGI) could differentiate all the culti*urs. Sufficient variability was present in cowpea cultivars to allow the use of isozyme electrophoresis as a method for cultivar identification. Therefore, ii could be used in variety identification to complement the morphological characters.Publication Open Access Plant growth flowering and fruit formation of tomato grown under protected culture(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1998) Weerakkody, W. A. P; Peiris, C. NProtected culture is a remedy for environmental problems of crop cultivation. However, seasonal weather changes adversely affect indoor grown plants. Therefore, this study was conducted to examine the affect of protected (indoor) culture and other improved technologies, often used in protected culture, on tomato (Lvcopersicon esculentum L.) grown with irrigation during the Maha season. Two indoor cultures together with improved technology and two outdoor (open-field) cultures with and without improved technology were used as treatments. Vegetative and reproductive growth of tomato were evaluated during the respective growth stages. Except at early vegetative growth, dry weather prevailed during the cropping season. Most of the vegetative growth parameters were not significantly different between the indoor and outdoor treatments. However, indoor culture showed significantly higher flowering and fruit formation. The shed house recorded the highest number of fruits per plant. Significantly higher vegetative growth was observed with the use of improved technologies, irrespective of the experimental conditions. Moreover, the improved technologies contributedfor greater number offlowers per plant but not for number of fruits. Indoor culture in combination with the improved technology assured greater vegetative growth, flowering and fruit formation of tomato when compared to outdoor culture under low rainy conditions that prevail during the Maha season. Except for fruitformation, comparative advantages of different indoor structures were not evident.Publication Open Access Fruit formation, marketable yield and fruit quality of tomato varieties grown under protected culture in two agro ecological zones during the rainy season(National Science Foundation: Colombo, 1999) Weerakkody, W. A. P; Peiris, C. N; Karunananda, P. HEnvironmental limitations in agriculture can be successhlly overcome wit11 the use of protected (indoor) culture. Howevel; the powtll and developme~t of indoor grown crops with pa~tial environmental control vary with season, location and crop genetic dif~"erences. This rescarcll was conducted to study the influence of agro-ecological conditions and varietal differences on fiuit development, yield and fiuit quality of' protected c~~lture grown tomato during the rainy season. The location, Rallangala (upcountry intermediate zone) enhanced the yield components, hit size and damage-free fruits under rainy weatller. Fruits at Peradeniya (midcountry wet zone) had higllcl. tolal soluhlc solids (TSS), fruit acidity and locular material contents compared to Rahangala. Protected culture gave greater iiuit formation, yield (fruit weight and numbcr of'marketahle fruits), f'luit size and damage-free fruits than the open field culture. As a result ofthe interaction between culture and locati.on, the hjghest yield and fruit size were reported at Rallangala while the highest TSS w'as reported at Peradeniya in protected culture. More marketable fiuits of cultivar T-245, Iligl~er f111it weight of cultivar Heat; Master and liiigher yield of cultivar Cariho were found, especially under protected culture. Caribo appeared to he suitable for both regions while Heat Master and T-245 were better adapted to Ral~angala and Pcradeniya, respectively. The polythene llouse with improved technology was more productive usder the agro-ecological conditions at Rallangala duxing MuIra season in terms of yield and external fiuit quality of tomato while it was more suitahle,for Peradeniya during XL~U, season in terms of internal fuit quality of tomato.Publication Open Access Yield and quality of tomato as affected by rainfall during different growth stages(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1997) Weerakkody, W. A. P; Peiris, C. N; Jayasekara, S. J. B. ACultivation of tomato (Lvcopersicon esculentum) is severely affected during the peak rainy periods in Sri Lanka, which leads to a seasonality in production andfluctuation ofprices. To study the nature of rain damage and to identify the critical growth stages prone to rain damage, staggered planting of tomato was practiced in the Mid Country Intermediate Zone during the Maha season. The rain damage was evaluated in terms of yield components, yield andfruit quality. During the vegetative growth and early flowering, rainfall was positively correlated with yield components andfruit quality. However, rainfall received during the late flowering phase reduced the weight andfinal number of fruits. During fruit growth, rainfall was positively correlated with fruit cracking andjuice pH. A negative correlation existed with other fruit defects. Hence, positive effects cf rainfall during vegetative growth and negative effects ofrainfall during reproductive growth were evident. Late flowering andfruit ripening stages were identified as critical for yield components while fruit growth andfruit ripenug stages were identified as critical for fruit quality.Publication Embargo Development of the major triterpenoids and oil in the fruit and seeds of neem (Azadirachta indica)(No longer published by Elsevier, 1996-09-01) JOHNSON, S; MORGAN, D. E; PEIRIS, C. NIn order to learn the best time for harvesting Neem (Azadirachta indica) seeds, the amount of the five major triterpenoids, together with the oil content have been determined throughout a fruiting season in six selected trees in Sri Lanka. The triterpenoid content and the relative proportions of the major compounds changed little from the hard green fruit stage to mature seeds, while the oil content increased markedly with time. The highest content of azadirachtin (10 mg g-1seed kernels) was recorded in newly ripened seeds. There was some loss of salannin and azadirachtin in storage after harvesting for up to 6 months.Publication Open Access Establishment of embryogenic cell suspension culture of chilli (capsicum annum L. var. accuminatum fingerh) for somatic embryogenesis(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1996) Nandakumar, J; Bandara, J. M. R. S; Peiris, SChilli [Capsicum annum L. var. accuminatum Fingerh] is one of the important spice crops ofSri Lanka. Embryogenic suspension cultures of chilli were developed with an objective to induce somatic embryogenesis Successful callus induction was obtained from both leaves and cotyledons of two weeks old seedlings in MS medium containing 1 ppm 2, 4 • D, after incubation in the dark for two to three weeks. A combination ofKinetin (0.x ppm) and 2,4- D (1 ppm) promoted callus proliferation at a high rate. Cell suspension cultures were established using 2 g of four week old leaf and cotyledon calli in 20 ml of liquid MS medium with 1 ppm 2, 4- D in 100 ml Erlenmeyer flasks. Weekly sub culturing was performed. MS medium with 2. 4-D (1 ppm) stimulated embryogenesis on cotyledon callus after 12 weeks in culture. Embryogenic calli formed are pale yellow to brown, compact, organized and nodular in appearance. It comprised of small, richly cytoplasmic cells without large vacuoles. Both initiation of embryogenic cells and the subsequent development of these cells into embryoids occurred in the. same MS (2, 4-D 1 ppm) medium. Within a period of five to seven days, 12 week old, 20 ml of embryogenic cell suspension produced 14 proembryoids After 7-14 days they developed into heart stage and to mature embryoids Plantlet development has not observed until now in the tested MS media, containing activated charcoal, zeatin, IBA and GA3.Publication Open Access An evaluation of genetic diversity in micropropagated anthurium using starch gel electrophoresis(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1992) Peiris, S; Mantell, S. H; Peiris, C. N; Senanayake, Y. D. AAnthurium andreanum Lind is a cut flower which is in high demand in the local and export cut flower trades in Sri Lanka. For commercial production of export anthurium cut flowers, it is essential that the selected elite qualities of the flowers borne on this original mother stock plants are maintained consistantly through many generations on vegetative multiplication. Tliis paper reports on stanch gel electrophoresis which was adapted successfully on anthuriums to evaluate genetic diversity if any, in plants derived either from seedlings, conventional stem cuttings or micropropagated clonal plants. Buffered leaf extracts were compared by means of horizontal starch gel electrophoresis to check the variability in cv. 'Crinkled Red'. Isoenzyme banding patterns of malic dehydrogenase (MDH), 6 phosphogluconic dehydrogenase (6 PGDH), phosphogluco isomerase (PGI) and diaphorase (DIAP) were used. Extracts of 105 seedlings, 60 clonal plants produced through rhizome cuttings and 150 in vitro propagated plants were compared to detect possible somaclonal variations in the daughter plants produced. Results of starch gel electrophoresis showed that extracts of seedling plants contained variations, expressed as percentages showing deviant patterns in all five isoenzyme systems assessed: MDH 14%, 6 PGDH 13%, GOT 12%, PGI 14% and DIAP 16%. None of the clonal plants or in vitro propagated plants tested using this technique showed variations in any of the isoenzyme compared. Tlie results of this study showed the genetic diversity in anthwium seedling plants and confirmed that stability was maintained in vegetatively propagated and in vitro propagated plants. Since in vitro propagation produces a large number of uniform and genetically stable plants, in vitro multiplication would appear to be suitable for use in the Sri Lankan floriculture industryPublication Open Access Biodiversity of fruit and other tree species in the Huruluwewa watershed with emphasis on their economic utility(Postgraduate Institute of Agriculture, University of Peradeniya: Peradeniya, 1997) Amarasinghe, A. A. Y; Peiris, B. C. N; Peiris, SThis stud}1 attempted to determine species and genetic diversity in the Huruluwewa wa'ershed considering basic information on native tree species with emphasis oi i fruit and other tree species of future economic utility. This study :vas carried out in different phases, namely, "reconnaissance survey" leading to specific information of the Huruluwewa watershed to determine the species diversity and "Identification of genetic diversity of fruit tree species" through starch gel electrophoresis techniques. Few groups of fruit tree species showing close similarities were used to establish the "Finger printing" through starch gel electrophoresis to identify the genetic diversity. The existing high degree of species diversity in the Huruluwewa watershed can be categorized into different groups based on their economic utility. These are fruit ti ee species, medicinal plants, firewood species, timber trees, ornamental plants food crops, shade trees, cover crops andfodder crops. Different banding patterns in the starch gel electrophoresis established for fruit tree species with closn morphological similarities, indicated the genetic diversity within and among fruit tree species in the watershed