A survey of the quality of brassica seed used for commercial transplant production revealed that overall germination was high but that there was a wide range of seed vigour, as assessed by the controlled deterioration test. These vigour differences were reflected in the performance of seed in modules, the use of low quality seed resulting in problems of a reduced rate of emergence and a lack of seedling uniformity. The improvement of seed quality was considered using three approaches. First, the use of seed soakwater conductivity as a means of predicting germination was investigated for individual seeds. This proved not to be a reliable means of sorting seeds. However, the combination of controlled deterioration followed by assessment of conductivity on bulks of seeds gave a good indication of vigour and was developed as a possible rapid vigour test. Secondly, the relation between seed size and seed performance was examined. No clear relationship was found between seed size and seed quality, although, seed size had a marked effect on seedling growth, the larger seeds consistently producing taller seedlings. Thirdly, a physiological means of seed improvement was considered. Aerated hydration in water columns was successful as an invigoration treatment resulting in increased germination rate, root length of seedlings and seed vigour leading to enhanced performance in modules. These improvements were maintained after drying and storage. The optimum short-term treatment was 8 hours hydration at 25oC. The improvement could be partly attributed to germination advancement and in addition the effect of temperature, aeration and the greater improvement of aged seeds suggested that repair processes were activated during aerated hydration. Also, prolonged hydration for up to 32 hours gave an improvement such that the performance of aged seed was not significantly different to unaged seed. Finally, one possible mechanism by which aerated hydration resulted in such improvements in seed quality was investigated. DNA synthesis began approximately 24 hours earlier in unaged than in aged seed. Hydration reduced this lag phase, indicating that the onset of DNA replication was accelerated. The use of hydroxyurea, an inhibitor of DNA replication, indicated that the repair of accumulated DNA damage may have been occurring between the 16th and 32nd hours of germination.

Magistrantūros studijų baigiamajame darbe pateikiami baltojo gūžinio kopūsto veislių atsparumo runkeliniam nematodui (Heterodera schachtii Schmidt, 1871) tyrimų in vitro ir in vivo sąlygomis rezultatai. Darbo objektas – in vivo ir in vitro sąlygomis išauginti baltųjų gūžinių kopūstų daigai, užkrėsti runkelinio nematodo (Heterodera schachtii Schmidt, 1871) cistomis. Darbo metodai: įvairių veislių gūžinio kopūsto veislių atsparumas in vitro sąlygomis atliktas įterpiant runkelinio nematodo cistas prie augalo šaknų (Feyaerts, Coosemans, 1992; Jalali, 1998; Soliman et al., 2005). Prieš įterpimą cistos buvo sterilizuotos 0,05 % HgCl2 tirpalu, laikant jas tirpale 3 min, po to tris kartus nuplaunant steriliu distiliuotu vandeniu (Müller, 1978; Feyaerts, Coosemans, 1992; Jalali, 1998). In vivo sąlygomis kopūstų daigai taip pat užkrėsti įterpiant prie augalo šaknų runkelinio nematodo cistas. Iš augalo šaknų nematodai buvo išskirti modifikuotu piltuvėliniu Bermano metodu kambario temperatūroje esant 2 parų ekspozicijai naudojantis binokuliaru MБC – 1 (Zuckerman ir kt., 1985; Šlepetienė, 1981). Augalų atsparumo vertinimas atliekamas nustatant naujos kartos patelių/cistų, rastų ant šaknų sistemos, skaičių (Harrewijn, 1987; Lelivelt, 1995; Voss et al., 1999; Cook, Noel, 2002). Darbo rezultatai. Baltojo gūžinio kopūsto veislės 'Jetma F1', 'Amager Kurzsturnking', 'Zora', 'Brunswick', 'Kamienna Glowa' ir 'Golden Acre' yra tinkamos H. schachtii plitimui, kaip augalai šeimininkai. Tiek in... [toliau žr. visą tekstą] / The master work presents the results of white cabbage variety resistance for sugar beet nematode (Heterodera schachtii Schmidt., 1871) in vivo and in vitro conditions. Object of the work – In vivo and in vitro conditions grown white head cabbage seedlings infected by sugar beet nematode (Heterodera schachtii Schmidt., 1871) cysts. Method of the work – different varieties of cabbages species resistance in vitro is performed by inserting sugar beet cyst nematode to the plant roots (Feyaerts, Coosemans, 1992; Jalali, 1998, Soliman et al., 2005). Prior to insertion of cysts were sterilized 0.05% HgCl2 solution, keeping them in a solution of 3 min, followed by rinsing three times with sterile distilled water (Muller, 1978; Feyaerts, Coosemans, 1992; Jalali, 1998). In vivo cabbage seedlings are also infected with the insertion of the plant's root cyst nematode. The plant's root nematodes were identified by Berman modified funnel method at room temperature for 2 days of exposure using binoculars MБC - 1 (Zuckerman et al., 1985; Slepetiene, 1981). Plant resistance assessment in identifying the next generation of females / cysts found on the root system (Harrewijn, 1987; Lelivelt, 1995, Voss et al., 1999; Cook, Noel, 2002). The results of work. White Cabbages cultivar 'Jetma F1', 'Amager Kurzsturnking', 'Zora', 'Brunswick', 'Kamienna Glowa' and 'Golden Acre' is suitable for (Heterodera schachtii Schmidt, 1871) spread as host plants. Both in vitro and in vivo conditions found that... [to full text]

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.93-105).