The Effects Of Several Pre-emergence Herbicides For Weed Control And The Quality On Vegetable’s Plug Seedling

The damage caused by weeds brings us serious challenge and leads to unnecessary economical loss in the process of the plug seedling. At present, the main method of weed control is manual removal in the process of plug matrix seedling, but it is inefficient and costly, also easy to hurt the plant seedling’s root. Chemical weed control has been matured, but there is no research about using chemical herbicide to control weeds. In order to simulate the phenomenon of weeds during plug seedling, this study chooses cucumber and tomato as the experiment materials and then mix the same species and quantity weed seeds and different application amounts of pre-emergence herbicides into the substrate in advance to test the cucumber and tomato seedlings’physiological, morphological, quality index and the weeds’ quantity, morphological index, dry weight and so on. Finally, we choose the best application amount of the most effective pre-emergence herbicide and survey the influence on the plug seedling at the same time. The study shows:1. The effect of weed control is enhanced with the increasing amount of application of pre-emergence herbicide. The dates of the maximum value of weeds are advanced to some degree. The first day’s amount of germination of weeds, the maximum value, the final value and the total dry weight of weeds are declining with the increasing application amount of pre-emergence herbicide, the weed control is on the contrary.2. The higher pre-emergence herbicide application can increase the cucumber and tomato’s root activity, root dry weight, exponent of stern seedling and root-top ratio, but significantly lower the G-value, total chlorophyll content, photosynthetic rate, soluble sugar content and other indicators of cucumber and tomato. Meanwhile, the seedling fully germination is delayed to some degree, and also the emergence rate of seedling. It is reflected more obvious on tomato than cucumber.3. During the process of plug substrate seedling, cucumber germinates on the same day or earlier and grows faster than the weeds. Therefore, the cucumber has advantage of competition. With the growth of cucumber, it has negative effect on the weed’s growth. However, the tomato is on the contrary. It germinates much later than weeds, and also grows much slower. So tomato has disadvantage of competition with weeds. As a result, tomato is easier leads to the breakout of weeds than cucumber.4. It is also found that most of weeds have been dead before germination, while some gradually die after germination even use different pre-emergence herbicide treat the nursery substrate. These weeds are usually not big after germination. This phenomenon occurred during the use of these three kinds of pre-emergence herbicides. It maybe the pre-emergence herbicides’ effect on the weeds that grow to a certain size. It also may combine the effect of competition between the plants and weeds.5. Through the different application amounts of the various pre-emergence herbicides dispose the nursery substrate, we pick up two optimal treatments to cucumber and tomato respectively. S4, S6, D6, D9, F1 and F2 perform better in the process of cucumber plug seedling. S6 performs best in the final experiment, while D9 and D6 take the second place. S4, S6, D6, D9, F2 and F3 perform better in the process of tomato plug seedling. S6 is also the best treatment in the final experiment, S4 takes the second place. The best treatments not only can control the weed’s germination and growth, but also firm the seedling.