本研究對臺灣野稗、野舌草、球花蒿草、螢藺、野茨菰、印度水豬母乳、水莧菜、多花水莧菜、母草、鋸葉定經草及喇叭草等十一種水田雜草在一、二期作期間之萌芽、營養生長、開花期、種子發育及種子生產量進行探討。各雜草在二期作狀況下之萌芽均較其在一期作者為早而且整齊；達到50%種子萌芽之時間，一、二期作分別在播種後4至20日及3至5日之間。葉數、株高及植株重量等資料均顯示各測試雜草其一期作間之營養生長較二期作間者為慢；一期作各雜草在播種後60日所聚集之生物量與其二期作中30日所聚集者相當。二期作狀況下雜草之開花期均較一期作者為早；前者在播種後27至45日間，後者在播種後49至85日間。兩期作開花所需時間之種內差異在14至48日間。期作間開花期之不同，主要與其環境之溫度有關。產生具有發芽力種子之時間，視雜草種類，短者在開花後7日內，長者在開花後14日以上。種子產量之數據顯示測試雜草均有在一季中大量繁殖之潛力。

Eleven paddy weeds,echinochlou erus-galli var. formosensis,Monochoria oaginalis var. plantaginea, Cyperus difformis, Scirpus juncoides, Sagittaria trifolia, Rotala indica, Ammannia baccifera, A. multiflora, Lindernia pyridaria, Vandellia anagallis and Ludwigia prostrata were tested of their seedling emergence, vegetative growth, flowering ,seed development and seed production in the first season (February June) and the second season (July-October) rice crops. Seedlings emerged earlier and more uniformly in the second season test than in the first one. Time to 50% seedling emergence of weeds teste ranged from 4-21 and 3-5 days after planting for the first and the second season trial, respectively. Data on number of leaf, plant height and plant weight demonstrated that vegetative growth of weeds in the first season test were consistently slower than those with the second season test. In general, for the same weed, it took 60 days in the first season trial to produce bio-mass comparable to that of 30 days in the second season one. It required less time for weeds to advance to the flowering stage in the second season trial, 27 to 45 days among species, than in the first season, 49 to 85 days among species. Intra-specific difference in initial flowering time between seasons ranged from 14 to 48 days. Seasonal variation in flowering time was proposed associated primarily with the temperature condition at the early stage of seasons. Weeds tested were found capable to develop germinative seeds at less than 7 dyas to more than 2 weeks after the appearance of anthesis. Large amount of seeds were produced by weeds suggested their tremendous otential of multiplication in a single generation.