溫度及除草劑丁基拉草對八種水田雜草萌芽之影響

Influence of temperature regimes and butachlor on the emergence and seedling growth of eight paddy weeds

"本研究針對稗草（Echinochloa crus-galli Beauv.）、螢藺（Scirpus juncoides Roxb.）、球花蒿草（Cyperus difformis L.）、鴨舌草（Monochoria vaginalis（Burm. F.）Presl）、野茨菰（Sagittaria trifolia L.）、紅骨草（Rotala indica（Willd.）Koehne）、母草（Lindernia procumbens（Krock.）Philcox）及多花水莧（Ammannia multiflora Roxb.）八種水田雜草，分別在日／夜平均溫21/17℃（模擬一期作水稻生育初期之低溫）、32/28℃（模擬二期作水稻生育初期之高溫）生長箱，及28.6/24.2℃之溫室環境中萌芽、生長及對除劑反應之探討。高溫生長箱內八種水田雜草於湛水後均出現一萌芽高峰期，鴨舌草、野茨菰、紅骨草及母草較稗草、螢藺、球花蒿草及多花水莧早約一星期，球花蒿草、野茨菰、紅骨草及母草之萌芽高峰期可持續3-6日；低溫下紅骨草及母草在湛水後5-10日亦出現萌芽高峰期，其餘測試草種子之萌芽率低且萌芽期持續較久，顯示32/28℃下雜草之萌芽較21/17℃為整齊。高、低溫下之種子萌芽始期，分別在湛水後2-3日及5-10日，萌芽平均日數依序為15-20日及25-30日間，高溫環境下之種子萌芽數為低溫者之1.5-3.0倍。溫室中稗草及螢藺在湛水後3日左右開始萌芽，萌芽數持續增加至一個月，鴨舌草、紅骨草及母草在3日後出現萌芽高峰期，10日後會迅速下降，野茨菰及多花水莧在6日後之萌芽種子數，呈現穩定不再增加之萌芽趨勢。溫室中種子萌芽平均日數亦介於25-30日間，萌芽種子數為最多。三種不同溫度處理中，溫室環境之雜草株高及鮮重生長最佳，顯示測試水田草在21/17℃及32/28℃之溫度範圍均可發芽，但生長適合溫度則為28.6/24.2℃。八種測試雜草之種源土於湛水後0, 3, 6, 9及12日，分別施用1.5 kg ha^（-1）劑量之丁基拉草粒劑，以湛水後0-6日（2-3葉）之植株達90 %以上之防治率，除野茨菰外，湛水後9日施藥，仍有75 %以上之防治效果，但12日後施藥對野茨菰完全無效，其他雜草的抑制也降至50 %左右。施藥後28日調查株高及鮮重，湛水後0-6日施用之丁基拉草，可明顯抑制大多數測試雜草之萌芽生長，但殘存之稗草、球花蒿草、鴨舌草、野茨菰及紅骨草，具有株高或鮮重恢復生長之潛力，至於9日及12日之藥劑處理效果已明顯降低。"

"The emergence and seedling growth of 8 paddy weeds, Echinochloa crus-galli, Scirpus juncoides, Cyperus difformis, Monochoria vaginalis, Sagittaria trifolia, Rotala indica, Lindernia procumbens, and Ammannia multiflora, were tested at different temperature regimes. Seedlings emerged earlier and more uniformly at higher temperatures (day and night temperatures of 32/28 °C) than at lower temperatures (day and night temperatures of 21/17 °C). Germination peaked at 32/28 °C in all 8 species, whereas at 21/17 °C, a peak of germination was detected for R. indica and L. procumbens. Other tested species emerged over a prolonged period at 21/17 °C. The time to initial emergence of weeds tested ranged from 5 to10 and 2 to 3 days after soil flooding at 21/17 °C and 32/28 °C, respectively. The MTE (mean time of emergence) values at 21/17 °C ranged from 25 to 30 days after soil flooding for all 8 species, whereas the MTE at 32/28 °C for tested species ranged from 15 to 20 days after soil flooding and was shorter than at 21/17 °C. Emergence characteristics, including initial time of emergence, magnitude of emergence, and mean time of emergence, of all 8 species grown under greenhouse conditions (with day and night temperatures of 28.6/24.2 °C) showed a similar pattern as those grown in growth chamber temperatures of 32/28 °C. Data on plant height and fresh weight demonstrated that growth was consistently slower for plants grown at 21/17 °C compared with those at 32/28 °C. The efficacy of butachlor in controlling tested paddy weeds was investigated in the greenhouse. Pot tests showed that butachlor provided over 90 % control at 0 to 6 days after soil flooding at the recommended application rate. Lower control with this herbicide was obtained when it was applied 9 to 12 days after soil flooding. Better control was achieved when butachlor was applied onto most tested weeds when they were younger than the 3-leaf stage."