"Biological weeding" was introduced in the previous section, and "Development of bioherbicides" and "Weeding with biotechnology" will continue in this section.
First of all, it is said that "development of biological herbicides".
At present, people have found hundreds of active substances with herbicidal effect in plants of more than 30 families and many microorganisms. Compared with synthetic traditional herbicides, these natural compounds have the advantages of non-pollution, low cost, no resistance to weeds, and a long duration of effect, so they can be developed into a new generation of herbicides. According to the current findings, there are two main ideas for the development of biological herbicides, as shown in Figure 1 below
In Figure 1, some results have been achieved in the development of plant-derived herbicides by extracting effective substances from plants. Table 1 below lists some of the substances found in plants with herbicidal activity:
The "strigostrine extracted from cotton root exudates" and "terpenoids extracted from desert plants" in the table have been successfully developed as plant-derived herbicides.
In addition, there are some achievements in the area of "isolating herbicidal components with herbicidal activity from microbial secretions and metabolites" shown in Figure 1. For example, the Netherlands produces biochon from the silverleaf fungus, a herbicide that promotes the decay of "woody weeds". In Japan, a natural herbicide dipropylphosate has been developed with the product of Fusarium, and its mechanism of action is shown in Figure 2 below
China has also made progress in the development of microbial herbicides: a strain of Streptomyces spp. has been screened, and its culture liquid can strongly inhibit the growth of sorghum, horsetail and amaranth, and the herbicidal active substances have been isolated and purified. In addition, herbicides such as "herbicidin" have also been extracted from the metabolites of actinomycetes in China, which can inhibit the growth of weeds such as barnyard grass and wild oats.
Now that we've introduced the development of biological herbicides, let's talk about how scientists use biotechnology to control weeds.
There are two most common ideas for using modern biotechnology to fight weeds, as shown in Figure 3 below
Targeted modification of plant performance can make the crop itself have excellent performance against weed competition. The genetic modification of some fungi that can produce weed-resistant secretions is because these fungi often have some defects, and after being modified, the purpose of cultivating excellent strains can be achieved, and it is more convenient for people to refine excellent herbicides.
There are three commonly used techniques for directional modification of plant performance: transgenic technology, hybridization, protoplast fusion technology, and systematic breeding technology. The specific principles and cases are shown in Figure 4 below
Genetic improvement methods for fungi can be broadly divided into two categories: gene transfer and gene recombination, and the characteristics of each are shown in Figure 5 below
In view of the space, the principles of the three new weed control strategies and some of the results achieved, this article is hereAlthough the use of biological strategies for grass control has many advantages, it also has certain limitations. In practical life, in order to achieve the effectiveness of weed control, people often use these strategies comprehensively and creatively according to the specific situation: (1) adopt methods such as multi-insect combined grass control, multi-bacteria combined grass control, one bacterium to control several grasses, and insect and fungus combined grass control to expand the herbicidal spectrum;(2) By using the diversity of the chemical structure of natural herbicidal compounds, by adjusting their chemical structures, pseudo-natural herbicides with higher activity, better selection and more ideal duration were developed(3) Use advanced biotechnology to breed new crop varieties that inhibit the growth of weeds and breed super strains to control weeds, and develop safe, broad-spectrum and efficient biological herbicides.
In conclusion, the application of biological strategies for grass control has broad prospects. The implementation of this method has brought agriculture into an unprecedented new stage of development and provided a strong guarantee for the realization of sustainable human development.