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   Critical period for weedy rice control in direct-seeded rice  
   
نویسنده Azmi M. ,Abdul Shukor J. ,Mohamad Najib M.Y.
منبع journal of tropical agriculture and food science - 2007 - دوره : 35 - شماره : 2 - صفحه:333 -339
چکیده    On-station trials were conducted in mardi seberang perai in main season 2004/05 and off-season 2005 to determine the critical period of weedy rice control in direct-seeded rice. this period generally consisted of two discrete periods, a critical weed free period and a critical time of weed removal. the gompertz and logistic equations were fitted to data representing increasing durations of weed control and weed interference, respectively. in the main season 2004/05, only weedy rice was allowed to grow in association with direct-seeded rice. other weeds were controlled with selective herbicide applications. in the off- season 2005, mixed weeds including weedy rice were let to grow in association with direct-seeded crop. a period of weedy rice control lasting up to 53 das prevented a yield loss of more than 5% in main season 2004/05. however, weedy rice competition could cause 5% yield loss if it allowed to compete with direct-seeded crop until 16 das. therefore, the critical period for weedy rice control was from 16 to 53 das. in off-season 2005, to prevent a yield loss of more than 5%, a period of weed free lasting 60 das is required and weed competition could cause 5% yield loss if it allowed to compete with directseeded crop until 12 das. it indicates critical period for weed control under mixed weed infestation from 12 to 60 das under 5% yield loss.
کلیدواژه critical period ,direct-seeded rice ,Gompertz and Logistic equations
آدرس Malaysian Agriculture Research and Development Institute, Malaysia, Universiti Putra Malaysia, Faculty of Agriculture, Malaysia, Malaysian Agriculture Research and Development Institute, Malaysia
پست الکترونیکی azmiman@mardi.my
 
     
   
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