Study Of Dayflower(Commelina Communis L.) On Biology And Control Technology

As a kind of annual late-spring weed, dayflower(Commelina Commw2is L), which existed mainly in dry land, such as soybean, wheat and corn, was very difficult to control. The biology of dayflower, including dormancy characteristic, emergence law, root-regeneration ability of the whole plant and branch in different soil moisture, was studied. It provided biological theoretic basis for scientific and effective control of dayflower, which, combined with herbicides selection test in field, helped to find the proper time and effective methods to control dayflower.The results showed:I.Germination of dayflower lasted about 25 days, beginning at the middle ten days of May, mushrooming from the last ten days of May to the first ten days of June, and stopping after the middle ten days of June. The germination density was 25 per sq.m. in the end. The percentage of germination was 95.2% of that of the whole year before June 10.2.The seeds of dayflower lay dormant after maturation. Seeds without any treatment after being collected for 20 days did not genninate. Dormancy of seeds was relieved by cold stratification, GA3, and being stored in the room during winter. Germination percentage and germination index was highest when seeds after 10 days of cold stratification were tested.3.Dayflower was very easy to regenerate roots if only it had a knob. The rootregeneration ability depended on soil moisture. When soil moisture was less than 13%, the branch did not regenerate roots while the whole plant did partly, then withered little by little because plant was unable to grow up normally.4.The excellent weed control efficiency (WCE) was attained by application of acetochlor+clomazone + metribuzin or DE56+ acetochlor when treated in pre-emergence period; and maximal dose DE565 + sethoxydim or DE565 + imazethapyr when treated in early postemergence period. The efficiency of hand weeding or mechanical control was mainly determined by soil moisture and leaf stage. Dayflower was controlled effectively when moisture was less than 13% and there was no rain in 5-6 days. On the other hand, dayflower before two-leaf stage was controlled completely by any kind of effective weeding method because it had no root-regeneration ability.2OO1~5~Postgraduate~ You LIXInMajor~ Pesticide ScienceTutor:Zhao Chang Shan(Northeast Agricultural University Harbin 150030 China)...