The responses of 15 rice cultivars to low temperature during germination were studied in order to develop appropriate techniques to identify rice genotypes suitable for direct-wet seeding in the cooler <I>Boro</I> season. Most rice cultivars showed more than 90% final germination over a range of temperatures. When tested at 13.7°C, cultivars differed in their final germination and rate of germination. The rates of germination at higher temperatures were significantly related to the rates of germination at lower temperatures. Thermal times to 50% final germination also differed significantly. Artificial ageing for 48 hours clearly separated the cultivars which had different K<sub>i</sub><I> </I>(initial seed viability). Such measures of physiological age and their relationship with final germination suggested that low quality seed exhibited reduced low temperature germination. Differences in rates and final germination at lower temperature of unaged seed suggested genotypic differences between cultivars. Inconsistency in rates of seed deterioration was seen contrary to conventional theory. Storage of seeds up to 9 weeks in simulated Bangladeshi conditions showed reductions in final germination tested at 11°C but not at 20°C. The rates of chitting and germination were increased by pregermination hydration treatments. Emergence of rice cultivars from soil was greater in constant than in alternating temperatures. Higher final emergence was associated with faster emergence. Thermal time to 50% and 80% emergence differed between cultivars. Many of the seedling growth parameters were higher in constant temperatures where the rate of germination was faster. The outcome of these experiments is to highlight the potential for comparing rates of germination of large numbers of genotypes relatively rapidly at higher temperatures as a measure to predict germination at lower temperatures.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:369730 |
| Date | January 2001 |
| Creators | Ali, Md Gous |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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