| Summary: | 碩士 === 國立臺灣大學 === 農藝學研究所 === 89 === Summary
Carpetgrass（Axonopus affinis Chase） and Sourgrass（Paspalum conjugatum Berg.） are sod-forming, warm-season perennial grasses. These grasses withstand animal tramping, they could be used as turf grasses in Taiwan. This thesis was aimed to investigate the annual changes of germinability of the buried seeds, and also to understand how the environmental factors affecting seed germination and seedling emergence. Modeling seed germination by the concept of hydrothermal time and shoot elongation under field condition were also studied. The main results were summarized as follows:
1. The freshly harvested seeds of A. affinis and P. conjugatum were under conditional dormancy. The buried seeds were at the state of conditional dormancy during summer time and reliefed dormancy after last autumn. When the monthly exhumed seeds were planted in field, seedling emergence only occurred around spring.
2. In the temperature between 21.7℃ to 31.7℃, seeds of both A. affinis and P. conjugatum germinated well. Germination of both species were reduced when the water potential below -0.4 Mpa.The rate of emergence decreased when the seeds of A. affinis buried deeper than 0.2 cm and 0.4 cm for P. conjugatum. No seedling of A. affinis emerged when seeds were buried below 1.2cm and 3cm as of P. conjugatum. The seeds of P. conjugatum were more salt tolerant than the ones of A. affinis. At the concentration of 1.2 % NaCl solution, the rate of germination was decreasing rapidly and reached Zero at the concentration of 2 %, whole the 2 % of germination was recorded for P. conjugatum..
3. Parameters for estimating seed germination including Tb、Ψb（50）、ΘHT、σΨb were calculated by a probit function. The best estimated values for A. affinis were 12.5 ℃, -0.81 Mpa, 46 ℃Mpa-day, 0.436 Mpa, respectively, and for P. conjugatum were 15.5 ℃, -0.59 Mpa, 14 ℃Mpa-day, 0.444 Mpa, respectively. Data of days to shoot elongation and temperature were fitted by a quadratic function. Combining both functions, we were able to predict time to seedling emergence under field condition in both species.
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