Critical Period for Weed Control in Saturated and Flooded Field, and Chemical Weed Control in Direct Seeded Rice Under Saturated Condition
Two field experiments were conducted at MARDI station, Seberang Perai, Penang. The experiments were: 1) Critical period in saturated and flooded field (off season 2005 and main season 2005/2006); 2) Chemical weed control in saturated field (main season 2005/2006 and off season 2006). The objectiv...
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| 格式: | Thesis |
| 语言: | English English |
| 出版: |
2009
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| 主题: | |
| 在线阅读: | http://psasir.upm.edu.my/id/eprint/10704/1/FP_2009_27_A.pdf |
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| 总结: | Two field experiments were conducted at MARDI station, Seberang Perai, Penang. The
experiments were: 1) Critical period in saturated and flooded field (off season 2005 and
main season 2005/2006); 2) Chemical weed control in saturated field (main season
2005/2006 and off season 2006). The objectives of the study were: a) to determine the
critical period of weed competition under saturated and flooded field conditions; b) to
determine the efficacy of herbicides in controlling weed and their subsequent effect on
rice productivity under saturated field. The first study consisted of different weeding
periods under saturated and flooded field conditions. Meanwhile, the second experiment
evaluated ten widely used herbicides which were available in the market either
individually or as mixture, and sequentially applied in direct seeded rice fields during
the critical period of weed competition under saturated field condition. Results from the first experiment indicated that Summed Dominance Ratio (SDR) of
weed composition was different under saturated condition compared with flooded
condition for both seasons. The dominance ranking of weed groups in off season 2005
under saturated condition was sedges followed by grasses and broadleaved weeds, while
in main season 2005/2006, grassy weeds was the most dominant followed by sedges and
broadleaved weeds. Under flooded condition the dominance ranking of weed groups was
broadleaved followed by grasses and sedges where the trend was the same in both
seasons. The numbers of tillers, along with rice grain yield were significantly affected
by weed competition in both saturated and flooded condition. Yield loss due to weed
competition was higher in saturated condition (54.5%) than in flooded condition
(35.2%). Based on the 5% level of yield loss, the critical period in off season 2005 was
at 2-71days after sowing (DAS) under saturated condition, and 15-73 DAS under
flooded condition. In the main season 2005/2006, the critical periods were at 1-72 DAS
in saturated condition and 2-98 DAS in flooded condition. |
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