This research study was to develop methods for inhibiting the germination of cotton seeds. Germination rates after heating treatment at 80℃ with 10, 20, 30, 40 min. were 9.3, 9.3, 5.3 and 1.3 percentage, respectively. Heat treatment over 85℃ with 10 min. caused no germination of cotton seeds. Germination was significantly reduced with gamma rays treatment more than 10,000 gy, while the treatment within 2,000-8,000 gy induced less effects. Microwave processing for 30 seconds and 60 seconds inhibit the germination of cotton seed under 8 and 0%, respectively. As a physical treatment, rollmill milling with 1.5, 2, 2.5 mm gap inhibited any germination of cotton seeds. The optimum gap of roll-mill for processing physical cracking was below 51% of the thickness of seed.

Tree species can be considered as hosts for many epiphytes. Orchids as epiphytes display a biased distribution among hosts. It is possible that the barks of these hosts have some chemical and physical characteristics that influence for the seed germination of orchids. Dependence on symbiotic fungi for the seed germination is also a crucial factor for orchid distribution. Dendrobium aphyllum is an orchid species with restricted distribution in sub montane region of Sri Lanka. Aims of this study were (1) to determine the host tree specificity of the epiphytic D. aphyllum using physical and chemical bark characteristics of the host (2) to isolate and identify the symbiotic fungi in D. aphyllum roots and (3) to determine the effect of tree bark extracts on symbiotic seed germination of D. aphyllum. Methanol, dichloromethane, hexane and water were used to extract the chemical compounds in tree barks. Aqueous and organic bark extracts of non host species (Erythrina sp. ,Erythrina berteroana, Eurya accuminata, Semecarpus marginata, Symplocaceae cochinchinensis ) inhibited seed germination of D. aphyllum. However, the effect of host tree species (Eurya ceylanica, Actinodaphne stenophylla, Eurya sp., Antidesma zeylanicum, Citrus maxima, Semecarpus nigra-viridis and two Syzygium spp.) on seed germination fluctuated with the concentration of host bark extracts. Bark physical characteristics such as bark texture, peeling behavior and bark thickness showed positive correlation with host tree specificity of D. aphyllum.. Symbiotic fungus Rhizoctonia sp. was isolated as the associate in D. aphyllum roots.

Switchgrass (Panicum virgatum L.), a perennial warm-season grass established by seed has been recommended by the US Department of Energy as a model herbaceous biofuel crop. Neoteric seeds may be dormant resulting in delayed and sporadic germination and emergence, jeopardizing establishment of a good plant stand. Switchgrass dormancy may be alleviated by mechanical or chemical scarification, stratification, and after-ripening, suggesting physical and/or physiological dormancy. The underlying mechanisms and physiology of dormancy in these seeds; however, are not well understood. This work investigates the physiology of switchgrass seed dormancy; first by identifying the contribution of the different switchgrass structures (glumes, lemma, palea, pericarp/testa, endosperm) on regulating germination, and then by testing specific mechanisms of coat-imposed dormancy. We sequentially removed structures of freshly harvested seeds of two upland (Cave-in-Rock, Trailblazer) and two lowland (Alamo, Kanlow) cultivars. The main structure inhibiting germination was the pericarp/testa, with the lemma and palea (bracts) having a secondary effect that differed by genotype. Seeds with glumes and bracts removed, and pericarp/testa cut with endosperm either attached or removed just above the embryo, resulted in high germination percentages and rate, indicating no morphological dormancy, and no effect of the endosperm on germination. The lemma, palea, and pericarp/testa were neither a barrier for water uptake nor contained inhibitory compounds. By adjusting the oxygen concentration of the environment and the physical integrity of the covering structures, we found the enclosing structures acted as barriers to oxygen. Puncturing the pericarp/testa of seeds with glumes and bracts removed, enhanced germination at 1, 10, 21 or 100% oxygen. Combined results showed that the structural integrity of the pericarp/testa (primary) and lemma/palea (secondary) influenced germination, suggesting an important mechanical effect of these layers as barriers for radicle protrusion. Therefore, a combination of seed-coat mechanisms regulates germination in switchgrass seeds.

Wheat seed quality improvement through basic processing machines was investigated and quantified. It was observed that consistent seed quality could be achieved by efficient use of processing machines viz. air screen cleaners (seed pre-cleaner and seed grader) and specific gravity separator (SGS), irrespective of initial quality of the seed lot. The product and reject of these machines were evaluated for seed quality parameters. The physical purity of wheat seed (8.8% w. b.) lot was upgraded from 97.72% to 99.56%, and germination was improved from 79.8% to 85.3%, which made the seed lot acceptable as per the Indian Minimum Seed Certification Standards. Other seed quality parameters viz. test weight (36.76 g to 40.88 g), germination index (18.70 to 20.74), vigour index - I (1317 to 1650) and vigour index - II (98.56 to 112.77) were also improved. Air screen machines were found effective in improving physical purity and specific gravity separator improved the germination and vigour of the wheat seed lot.

Wheat seed quality improvement through basic processing machines was investigated and quantified. It was observed that consistent seed quality could be achieved by efficient use of processing machines viz. air screen cleaners (seed pre-cleaner and seed grader) and specific gravity separator (SGS), irrespective of initial quality of the seed lot. The product and reject of these machines were evaluated for seed quality parameters. The physical purity of wheat seed (8.8 % w. b.) lot was upgraded from 97.72% to 99.56%, and germination was improved from 79.8% to 85.3%, which made the seed lot acceptable as per the Indian Minimum Seed Certification Standards. Other seed quality parameters viz. test weight (36.76 g to 40.88 g), germination index (18.70 to 20.74), vigour index - I (1317 to 1650) and vigour index - II (98.56 to 112.77) were also improved. Air screen machines were found effective in improving physical purity and specific gravity separator improved the germination and vigour of the wheat seed lot.

Seeds of legumes are generally considered to have physical dormancy and to be orthodox, but most seed biologists are unaware of the various kinds and combinations of dormancy and storage behaviour in seeds of this family. The aim of our study was to document the dormancy and storage behaviour of seeds of 100 native and introduced tropical Fabaceae species in Sri Lanka and classify them into germination/storage behaviour categories. Moisture content (MC) was < 16% for fresh seeds of 94 species and >29% for those of six. Seeds of these six species had low tolerance for desiccation and for low temperatures. Thus, seeds of six species are non-orthodox and 94 species orthodox. Nine of the 100 species were non-dormant, and 2, 3 and 86 had physiological, physiological epicotyl and physical dormancy, respectively. Six germination/storage behaviour categories were identified among the 100 species. However, as in extratropical regions of the world, orthodox storage behaviour and physical dormancy are characteristic of seeds of the majority of species of Fabaceae in tropical Sri Lanka.

Soil physical properties can affect to seed germination and plant growth. Soil compaction will degrade soil physical properties which in term will affect to root penetration and developement in the soil. The improvements of soil physical properties is required to ensure seed germination and plant growth such as treatment to maintain soil bulk density is quite low. The purpose of this research is to study the influence of soil compaction (soil bulk density) to soil physical characteristics and seed gemination of peanuts and soybean. This research used Jasinga Podsolik soil, conducted at Soil Physical Laboratory, Departement of Soil Science and Land Resources, Faculty of Agriculture IPB. and Greenhouse of Center of Biological Resources and Biotechnology, Research and Community Service Agency, IPB (March-November 2009). Completed random design was used as experimental design and Duncan's Multiple Range Test (DMRT) was used to identify the effect of treatment. The bulk density result of the research showed that the increasing of soil bulk density (soil compaction) had significantly affect on pF curves, permeability rate, and soil resistance before or after planting. For peanuts, soil compaction significantly affect to plant height and root length. Soil compaction did not significantly affect of stem diameter, number of leaves, canopy or root biomass. For soybean, the influence of soil compaction did not significantly affect just only on plant height. Stem diameter, number of leaves, root length or root and canopy biomasses were not affected by soil compaction.

The present study was undertaken to understand the fruit and seed morphology, seed viability and effect of various physical and chemical factors on seed germination allowing us to explore the spread potential and/or seedling recruitment mechanism in Myriophyllum spicatum L.. The fruit of the species is a schizocarp, while as seed is a nutlet. The seed set was recorded to be ranging from 70.98-77.91% across the standing water populations, whereas no seed set was observed in running water populations due to the lack of an effective pollination system. The seed viability ranged from 85-90%. For in-vitro seed germination studies, the seeds were subjected to different physical and chemical treatments under alternate light and dark as well as continuous dark conditions. The seeds in control and those treated with different concentrations of GA3 and IAA and those whose epicarp and mesocarp were removed did not show any signs of germination. However, it was observed that surgical exposure of the embryo (cutting of hard endocarp of seed) has a promoter effect on germination and maximum percentage germination (76.66 ± 5.77) was recorded due to surgical exposure of embryo plus different concentrations of GA3. Moreover, a good germination percentage was recorded in seeds subjected to chilling treatment. Further, it was observed that seed germination of one-year-old seeds was less if compared to the current year seeds and overall percentage germination was higher in alternate light and dark if compared to continuous dark conditions in all the treatments.Thus, we conclude that the dormancy of the seeds is due to the hard endocarp and that the light has a promoting effect on germination. With the increase in the age of the seeds, there is decrease in their viability and hence germination. The chilling winter temperature of the Kashmir is responsible for breaking the hard endocarp of the seeds leading to their germination and hence spread of the populations. | The present study was undertaken to understand the fruit and seed morphology, seed viability andeffect of various physical and chemical factors on seed germination allowing us to explore thespread potential and/or seedling recruitment mechanism in Myriophyllum spicatum L.. The fruit ofthe species is a schizocarp, while as seed is a nutlet. The seed set was recorded to be ranging from70.98-77.91% across the standing water populations, whereas no seed set was observed in runningwater populations due to the lack of an effective pollination system. The seed viability ranged from85-90%. For in-vitro seed germination studies, the seeds were subjected to different physical andchemical treatments under alternate light and dark as well as continuous dark conditions. Theseeds in control and those treated with different concentrations of GA3 and IAA and those whoseepicarp and mesocarp were removed did not show any signs of germination. However, it wasobserved that surgical exposure of the embryo (cutting of hard endocarp of seed) has a promotereffect on germination and maximum percentage germination (76.66 ± 5.77) was recorded due tosurgical exposure of embryo plus different concentrations of GA3. Moreover, a good germinationpercentage was recorded in seeds subjected to chilling treatment. Further, it was observed thatseed germination of one-year-old seeds was less if compared to the current year seeds and overallpercentage germination was higher in alternate light and dark if compared to continuous darkconditions in all the treatments.Thus, we conclude that the dormancy of the seeds is due to thehard endocarp and that the light has a promoting effect on germination. With the increase in theage of the seeds, there is decrease in their viability and hence germination. The chilling wintertemperature of the Kashmir is responsible for breaking the hard endocarp of the seeds leading totheir germination and hence spread of the populations.Avaliação de parâmetros de qualidade de sementes e efeito de tratamentos físicose químicos na germinação de sementes de Myriophyllum spicatum L.ResumoO presente estudo foi realizado para compreender a morfologia do fruto e da semente, a viabilidadeda semente e o efeito de vários fatores físicos e químicos na germinação de sementes, permitindo-nosexplorar o potencial de disseminação e/ou mecanismo de mudas de recrutamento em Myriophyllumspicatum L. O fruto da espécie é um chisocarpo, enquanto a semente é uma noz. A produção desementes variou de 70,98 a 77,91% entre as populações de água paradas, enquanto que nenhumconjunto de sementes foi observado em populações de água corrente, devido à falta de um sistemaeficaz de polinização. A viabilidade das sementes variou de 85-90%. Para estudos in vitro de germinaçãodas sementes, as sementes foram submetidas a diferentes tratamentos físicos e químicos sob luz eescuridão alternadas, bem como contínuo escuro. As sementes de controle e aquelas tratados comdiferentes concentrações de GA3 e IAA e aquelas cujo epicarpo e mesocarpo foram removidosnão mostraram quaisquer sinais de germinação. No entanto, observou-se que a exposição cirúrgicado embrião (corte do endocarpo rígido de semente) tem um efeito sobre a germinação e efeitopromotor sobre a germinação e um percentual máximo (76,66 ± 5,77) foi registada por exposiçãocirúrgica do embrião a diferentes concentrações de GA3. Além disso, a percentagem de germinaçãofoi observada em sementes submetidas ao tratamento de resfriamento. Ademais, observou-se quea germinação de sementes de um ano de idade foi menor em comparação com as sementes doano corrente e a percentagem de germinação em geral foi maior quando houve luz e escuridãoalternadasse comparadas com as em condições de escuridão em todos os tratamentos. Assim, podeseconcluir que a dormência das sementes é atribuída à rigidez de endocarpo e que a luz tem um efeitopromotor sobre a germinação. Com o aumento da idade das sementes, há redução na viabilidade e,portanto, na germinação destas. A temperatura do inverno frio da Caxemira é responsável por quebraro endocarpo duro das sementes, o que leva à sua germinação e, consequentemente, à disseminaçãodas populações.

Both germination and seedling establishment in palm trees are strongly influenced by the morphoanatomy of the fruits, although the interactions of these processes with ecophysiological aspects are not yet well understood. The present work evaluated structural and physiological aspects of seed germination in Attalea vitrivir, a species living under the seasonal climate of the Cerrado (Brazilian savanna) biome. We studied morphology, anatomy and histochemistry of the fruits and seedlings, the effects on germination of the pericarp, of diaspore storage conditions, germination temperature, removal of the operculum, and of gibberellic acid (GA3) application, and characterized the imbibition process of the seeds. Germination depends on a series of complex interactions between structures and physiological processes. The pericarp protects the seed and also causes physical dormancy that, when interacting with the temperature regime, can delay germination until subsequent rainy periods. Some seeds demonstrated non-profound physiological dormancy associated with restricted germination imposed by the operculum. Germination and initial development result from the elongation of the cotyledon cells and are affected by the activities of two distinct meristems in the proximal region of the embryo. The haustorium develops an invaginated secretory epithelium and aerenchyma, and actively participates in seed reserve mobilization. The adaptation of A. vitrivir to the Cerrado environment, with a strongly seasonal climate, is favored by its diaspore structure, by the abundance of endosperm reserves that allow the seedlings to survive for a long period above soil level, and by a seedling development pattern that protects the vegetative axis by deep burial.