| Summary: | 碩士 === 國立嘉義大學 === 農藝學系研究所 === 107 === Two rice varieties (TNGS22 and TK2) were used in this study to evaluate the relationship between plant canopy and weed competition under different nitrogen application rates and planting densities treatment. Analysis the changes in canopy drift of light diffusion proportion (DIFN) development and weed growth and number of varieties in different crop season and growth stage. The result showed that the DIFN between TNGS22 and TK2 in first crop season have no significant difference however, in second crop season, the DIFN under different nitrogen application rates and planting densities were significantly affected in TK2. The weed growth performance at panicle initiation and heading stages of TNGS22 and TK2 under different nitrogen rates and planting densities were further observed. It showed that the weed species and weed weights have no different significantly in first crop season among rice varieties, nitrogen application rates, and plant densities. In opposite, the weed growth properties are closely negative correlated to plant densities in second crop season. Besides, the weed performance was significant decreased in TNGS22 (horizontal canopy type) than in TK2 (upright canopy type). In concluded, the higher atmosphere temperature at the early stage in the second crop season, may have a promoting effect on the growth of weeds in rice fields. It is a useful strategy to decrease the weed competition by selecting optimum rice variety and plant density were recommended.
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