頁籤選單縮合
題名 | 大豆長期連施殺草劑積留頑草變遷與產量試驗 |
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作者 | 王啟柱; | 書刊名 | 中華農學會報 |
卷期 | 92 1975.12[民64.12] |
頁次 | 頁31-40 |
關鍵詞 | 大豆; 殺草劑; 頑草; |
語文 | 中文(Chinese) |
英文摘要 | The application of prometryne (Gesagard), linuron (Lorox) and alachlor (Lasso) sometimes showed a slight injury on soybean under unusual weather conditions. However, there were no enough accumulative residue that significantly damaged the growth and production of the crop after 4-8 months interval repeated application with six consecutive crops of three successive years. The weed population on the field was investigated before the experiment started. There were twenty seven weed species with nineteen major vs. eight minor ones. After repeated application of the herbicides, the susceptible weeds gradually diminished, but a few tolerant and resistant species became dominant. At the end of the third year, Alternanthera spp. were the most dominated species in all herbicide treatments, Eleusine indica and Digitaria sanguinalis were the second and third in prometryne; Cyperus rotundus and Eleusine indica or Panicum repens were the second and third in linuron and alachlor respectively. Other species changed according to their different selectivity of herbicides. However, the general trend was that the number of weed species reduced gradually from twenty seven to only three or four species at the end of the experiment. Certainly, the shift of weed species caused the decrease of the effectiveness of chemical weed control (Table1, 2 and 4). The mixed application and rotated application of the three herbicides, from crop to crop, could hardly prevent the tendency of weed shifting. Additional handweeding with or without earth-up sub-treatments gave a little better effect for preventing such a tendency. The seed yields of soybean by repeated application of the herbicides for six consecutive crops of three years had no any trend of gradual reduction (Fig. 1). The factors affecting the seed production were due to the growing season and climate rather than the accumulative residual toxicity of the herbicides. Among the three herbicides, linuron gave the highest yield of 1,547.3 kg/ha in average, alachor and prometryne were 1,480.9 and 1,363.5 kg/ha respectively. The yields of the mixed application and rotated application were 99.4% and 93.5% against the herbicides applied alone. Additional handweeding with or without earth-up increased the yields 18.7% and 20.4% respectively. However, these practices also increased the cost of weed control. Methods for preventing the shift of weed species and reducing the accumulative residual toxicity in multiple cropping areas with repeated application of herbicides were suggested. |
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