Papers by Gehan Jayasuriya
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Proceedings of International Forestry and Environment Symposium, Nov 14, 2019
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Ecological Research
Tropical lowland rainforests are considered to be ecologically important refugia of national and ... more Tropical lowland rainforests are considered to be ecologically important refugia of national and global significance, yet wide‐scale deforestation and degradation of tropical lowland rainforests lead to losses in biodiversity. Seed storage behavior information is required for the effective restoration of these forests. Here, we studied the seed storage behavior of 42 selected tropical lowland rainforest tree species from Sri Lanka with the aim to test the reliability of current experimental methods and predictive models to predict the desiccation sensitivity of seeds. Seed storage behavior was experimentally determined through the 100 seed method and the results were compared with three predictive models; thousand seed weight–moisture content (TSW–MC), seed coat ratio–seed mass (SCR–SM), and phylogenetic affiliation models. Based on the 100 seed method, 28 species were identified as desiccation sensitive and 14 species were identified as desiccation tolerant. Compared to the 100 see...
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Plants
Five species of wild Oryza (O. nivara, O. rufipogon, O. eichengeri, O. rhizomatis and O. granulat... more Five species of wild Oryza (O. nivara, O. rufipogon, O. eichengeri, O. rhizomatis and O. granulata), including the endemic species O. rhizomatis, have been recorded in Sri Lanka. These species are facing continuous decline in their populations due to natural and anthropogenic processes, with habitat loss being the main threat. This study aimed to provide information on the distribution, the current status of ex situ and in situ conservation, and to identify high-priority species and sites of wild rice in Sri Lanka, in order to improve the effectiveness of conservation efforts. Occurrence records of Sri Lankan wild rice species were collected from literature, gene banks, and field surveys. The distribution of these species was mapped, and areas with high species richness were identified. A gap analysis was conducted to determine the high-priority areas and species for ex situ and in situ conservation. It was found that about 23% of the wild rice populations in Sri Lanka were within p...
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Seed Science Research
Mangroves are one of the most important ecosystems in the world being found in the tropical–subtr... more Mangroves are one of the most important ecosystems in the world being found in the tropical–subtropical belt. Despite their significance, they have been highly disturbed due to many anthropogenic and natural causes. A significant effort has been made to restore mangroves around the world. However, a lack of information on the seed biology of mangrove species has impeded restoration. Thus, this study aimed to produce a seed dormancy profile for selected plant species of mangroves in Sri Lanka. This profile would allow restoration ecologists to better understand what kinds of dormancy are present, how to alleviate dormancy and how to best stimulate germination to generate seedlings for nursery stock or out-planting. Mature fruits/seeds were collected from coastal zone mangroves in Sri Lanka. Germination and imbibition of non-scarified and manually scarified seeds and embryo:seed length (E:S) ratio of fresh and radicle-emerged seeds were evaluated to assess the class of dormancy. Of th...
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Ecological Research
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Journal of The National Science Foundation of Sri Lanka, Sep 24, 2015
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Journal of the National Science Foundation of Sri Lanka, 2021
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Lantana camara is a native shrub to West Indies. It has been introduced to several tropical and s... more Lantana camara is a native shrub to West Indies. It has been introduced to several tropical and sub tropical countries. Now this plant has become invasive in these countries including Sri Lanka. The objective of this study was to gather basic information on seed biology of L. camara to aid in controlling it. Seeds were collected from numerous shrubs in Kandy and Ambalangoda. Seed moisture content (SMC), imbibition and germination of untreated and manually scarified seeds were determined. Effect of dormancy breaking treatments was studied. Length, width, mass, SMC and germinability of developing seeds were examined. Seed Moisture Content of L. camara (12.9%) suggested that seeds are orthodox. Both untreated and manually scarified seeds imbibed water in similar rate. None of the seeds germinated in light/dark and constant dark conditions. Further, seeds contained a fully developed embryo. Thus, it was concluded that L. camara seeds have physiological dormancy. Only a few seeds respond...
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Invasive species are the second largest threat to biodiversity loss in the world. Clidemia hirta ... more Invasive species are the second largest threat to biodiversity loss in the world. Clidemia hirta is a common invasive species found in disturbed sites such as along forest foot paths in tropical lowland-wet evergreen forests of Sri Lanka. Comparative information on seed biology of invasive species with that of the native species in the same habitat is crucial for the management of invasive species. Thus, we studied the seed biology of Clidemia hirta with that of three native species, Schizostigma hirsutum, Melastoma malabathricum and Plecranthus kanneliyensis that share the same habitat of C. hirta. Mature, ripen fruits of all the species were collected from at least ten individuals in Sinharaja rainforest and transported to the University of Peradeniya and experiments were initiated within 2-3 days of seed collection. Seed Moisture Content (SMC) was determined through the oven dry method. Seed germination was studied at 25 or 32 C in light/ dark (12hrs/12hrs), dark and green light ...
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Proceedings of International Forestry and Environment Symposium
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Seed Science Research
Plant community-level studies on seed dormancy traits are important to understand and determine t... more Plant community-level studies on seed dormancy traits are important to understand and determine the significance of seed dormancy in different ecosystems. Hence, we studied seed dormancy and other related seed biological traits of 42 selected tropical lowland rainforest tree species from Sri Lanka, aiming to address seed dormancy class(es) for a biodiverse tropical lowland wet zone forest community and the relationship between dormancy classes, forest strata and seed dispersal mechanisms. Seed germination, imbibition, embryo length:seed length ratio, embryo morphology and the effect of gibberrelic acid on seed germination were determined. Sixty-two percent of the species with T50 < 30 days were identified as having fast-germinating seeds and the remaining 38% with T50 > 30 possessed slow-germinating seeds. Seeds of 33 species had fully developed embryos, while nine species had underdeveloped embryos; three had morphological dormancy (MD) and six morphophysiological dormancy (M...
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Flora, 2022
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Oryza-An International Journal on Rice, 2020
Although the demand for traditional rice varieties has increased, low initial germination and poo... more Although the demand for traditional rice varieties has increased, low initial germination and poor storability of these varieties impede its popularization. Thus, the aim of the study was to improve the seed quality using priming treatments and to suggest an effective storage practice of two of the traditional rice varieties; Suwendal and Batapola-el, in Sri Lanka. Seeds were subjected to hydro-priming under various time periods (0, 24, 48 and 72 hours). Seeds were stored in gunny, polysac and polythene bags at room temperature, 25 and 8 °C. Seed quality of primed and stored seeds was evaluated using seed germination, seed vigour (seedling growth and conductivity) and seedling emergence. Hydro-priming for 72 hours has increased the seed germination of the two varieties significantly compared to other priming methods. Further, seeds primed for 72 hours had the highest vigour and highest seedling emergence in both varieties. Storing Suwendal and Batapola-el seeds in polythene bags at ...
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Proceedings of International Forestry and Environment Symposium, 2017
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With the increased demand, wild herbal medicinal plants are over exploited from wild populations.... more With the increased demand, wild herbal medicinal plants are over exploited from wild populations. Lack of information on seed biology is an impediment in propagation and conservation of these species. Thus, the main aim of the study was to determine the seed germination behavior of eight medicinal plant species from Sri Lanka, assisting their conservation. Seeds were collected from the wet zone of Sri Lanka from at least five individuals from each species. Seed and embryo morphology was recorded. Seed moisture content (SMC) was determined by an oven dry method. Standard hundred seed test was conducted to determine the desiccation sensitivity. Seeds were incubated at 32o and 25o C in light/dark or complete darkness and signs of imbibition were observed. Effect of GA3 and manual scarification on seed germination was studied. Four replicates of at least 12 seeds were used in all experiments. Arcsine transformed data were analysed using one-way ANOVA. Seed size varied from 0.9 to 3.8 cm...
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Knowing seed germination phenology is important in propagation and thus conservation of plant spe... more Knowing seed germination phenology is important in propagation and thus conservation of plant species as many of the plants regenerate through seeds naturally and easily. Knowledge on seed biology of a species plays a vital role in both ex-situ and in-situ conservation. Thus, we aimed to study seed biology of three Strychnos species from Sri Lanka which are of conservation importance, S. potatorum L.f. and S.nux-vomica L. in dry zone and S. benthamii C. B. Clarke in wet lowlands and montane regions. Seed moisture content was determined for study species by an oven dry method. Desiccation sensitivity of seeds was determined using 100 seed method proposed by Pritchard et al. (2004). Effect of different temperatures (32 and 25o C) and Gibberellic acid (GA3) concentrations (500 and 100 ppm) on seed germination was evaluated. Seeds were incubated in Petri dishes on moistened (with distilled water or GA3) tissue papers in light/dark (12/12hr) condition. Embryo length: seed length ratio (E...
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Proceedings of International Forestry and Environment Symposium, Jul 18, 2013
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Journal of the National Science Foundation of Sri Lanka, 2013
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Papers by Gehan Jayasuriya