Michelle Chen is an original scientist. He is good at learning, quick thinking, brave in innovation, and attaches importance to the combination of theory and production practice, which has made great contributions to plant pathology in China. As early as 194 1, when he graduated from the Department of Plant Pathology of Jinling University, his thesis "Study on Wheat Leaf Spot" proved the weak parasitic effect of Epicoccus. 1942, his master's degree project "Study on Fungal Physiology" found that the spore germination of Penicillium citri needed auxin, which was more than ten years earlier than that of foreign countries. 1949, his paper "inorganic nutrition of pythium" was published, and then the nutritional problems of the strain were further studied. It was found that the toxic effect of amino acids was more than ten years earlier than that of foreign countries.
In the early 1950s, apple tree rot broke out in northeast China, causing serious harm. Michelle Chen should go to the northeast urgently, and cooperate with researchers from the Fruit Research Institute of China Academy of Agricultural Sciences to conduct a systematic and in-depth study on the disease. It was found that the disease was caused by the decline of disease resistance of trees, which laid a theoretical foundation for the prevention and treatment of apple tree rot. His disease prevention strategy, which focuses on strengthening cultivation management and improving the vitality of apple trees, has achieved great success after being popularized and applied in production.
He also studied apple rust and anthracnose, and published monographs and papers. Anthracnose is a serious disease in the late growth stage of apple. After his painstaking research, it was found that the pathogen not only infected in the late growth stage of apple, but also began to infect in the young fruit stage, but the disease did not develop immediately, and the pathogen lurked in the young fruit stage.
In terms of fruit tree diseases, Michelle Chen also studied citrus Huanglongbing. Although it was mistaken for a virus at that time, it was also found that there was citrus fast decay virus in China, and it was asymptomatic. When he studied the black spot of sweet potato, he also found a similar phenomenon. In particular, the sweet potato dry rot pathogen not only has latent infection characteristics, but also can infect sweet potato with black spot pathogen. A similar result was obtained in the study of bark decay directed by him. His research results enriched the understanding of pathogen infection in plant pathology.
Second, the pioneer of biological control of plant diseases
Biological control of plant diseases is developed from the study of the ecology of soil-borne pathogens. As early as 1940s, Michelle Chen studied the physiology of pythium, a soil-borne pathogen. In the mid-1950s, he made a systematic investigation and study on diseases in china rubber, especially root diseases.
He found that there was no rubber white root disease in Hainan Island and suggested planting clover rubber. Decades of production practice have proved that his suggestion is correct. In order to systematically introduce the new progress in the ecology of soil-borne pathogens and the prevention and control of soil-borne diseases abroad, he translated the representative monograph Root Fungi and its Prevention into Chinese and introduced it to domestic academic circles. In the late 1950s, while studying in Germany, Michelle Chen mainly studied antagonistic bacteria against plant pathogens.
The first half of 1960s was an important stage for Michelle Chen to form his unique academic thought. In his research on the diseases of fruit trees, trees and field crops, he revealed the latent infection of many pathogens and the disease-free carrier phenomenon of plants, and more deeply realized the harmful influence of pathogen-only theory, which unilaterally emphasized the role of pathogens in pathogenesis, on the development of plant pathology, which became the basis for his new concept of "plant natural ecosystem". At that time, the international plant pathology community introduced the ecological viewpoint into plant pathology and put forward the viewpoint of developing biological control based on the ecological research of soil-borne pathogens. It can be said that Michelle Chen coincides with this view. Unfortunately, the "Cultural Revolution" interrupted his exploration in this field.
During the period of 1978, Michelle Chen systematically consulted foreign literatures in the field of plant diseases, and decided to further carry out systematic research on the ecology of soil-borne pathogens. It was found that there were not only pathogens but also many types of microorganisms in cotton ducts. In the same year, he gave a report entitled "Modern Plant Pathology and Its Development" at the Yangshuo Conference organized by China Institute of Plant Pathology, which promoted the recovery of plant pathology in China. His report combines his academic viewpoint, that is, the ecological viewpoint in plant pathology.
In order to promote the development of biological control of plant diseases more effectively, under the auspices of Michelle Chen, Beijing Agricultural University established the first biological control laboratory of plant diseases in China from 65438 to 0979, edited the internal publication Biological Control of Plant Diseases, and organized the compilation of books such as Ecological Research Methods of Soil-borne Pathogens, Biology and Control of Rhizoctonia, and Microbial Ecology. These materials and books are still used by colleagues for reference.
In addition to recruiting graduate students for special research, under his auspices, the Biological Control Laboratory also held a three-year advanced course on biological control of plant diseases to guide young plant protection workers inside and outside the school to carry out research-based training while studying; Comprehensive exploration was made in the fields of vegetables, fruit trees, trees and medicinal plants, and important research results were obtained, which provided scientific basis for the establishment of new disciplines.
It is found that there are many kinds of microorganisms on the surface and in the body of plants, including microorganisms that can infect plants and cause diseases, "harmful bacteria" that are harmful to plants but do not infect plants, and "beneficial bacteria" that can inhibit pathogens to alleviate diseases or stimulate plant growth and development. In some cases, there are interactions between these microorganisms and between microorganisms and plants. Based on these research results, combined with decades of scientific research and teaching experience, and referring to relevant literature at home and abroad, a new concept of plant natural ecosystem was put forward, and under the guidance of this academic thought, "yield-increasing bacteria" widely used in agricultural production was created. From 65438 to 0984, he held an unprecedented seminar on soil-borne diseases and biological control in China, which further promoted the research and development of biological control of plant diseases in China. 65438-0986 opened a new course-Ecological Plant Pathology for graduate students, and systematically introduced the theoretical research and applied technology in this new field. His research was strongly supported by leaders at all levels. 1988, the Institute of Plant Ecological Engineering was approved by the Ministry of Agriculture.
Third, meet the urgent needs of agricultural production and be loyal friends of farmers.
Michelle Chen believes that the vitality of plant pathology lies in the need of agricultural production and the ability to solve the problem of plant disease prevention in agricultural production. He not only educates the younger generation in this way, but also practices it.
In the early days of the founding of New China, apple tree rot was seriously prevalent in the northeast apple producing areas, resulting in heavy losses. Leading departments at all levels called on scientific and technological personnel to go to the front line to study and solve the diseases that caused farmers to starve and freeze. Michelle Chen resolutely went out of colleges and universities, went deep into reality, devoted himself to field investigation and study, visited fruit farmers, obtained first-hand information, and, together with other technicians, finally solved the problem of prevention and treatment of the disease through years of devoted research.
In the mid-1950s, citrus scab occurred seriously in southern China, which needs to be solved urgently. From Michelle Chen to Huangyan, Zhejiang, the experiment proved that Bordeaux mixture had a good control effect, and it was quickly applied in a large area of citrus orchards, and then it was further popularized in southern provinces. Sweet potato is an important food crop. Because of black spot disease, it constitutes an important limiting factor of sweet potato production. In some provinces, even cows were poisoned by eating sweet potatoes with black spot disease. Michelle Chen immediately put into research to cope with the urgency of production. A large number of experimental studies in epidemic areas in Northeast China found that soaking sweet potato seeds with borax can effectively reduce the harm of black spot disease.
After that, he publicized and demonstrated to the leading departments, technicians and the masses with great enthusiasm, which was quickly accepted by the masses and widely used, reducing the harm of black spot disease.
In the early 1990s, chestnut exported from China to Japan suffered a lot of dry rot during transportation. The appearance symptoms of the diseased chestnut are not obvious, but the nuts are dry and inedible, which seriously affects the export of chestnut. The research team led by Michelle Chen put into research, and soon found out the cause of chestnut dry rot, and found that it was a compound infection of many pathogens, which caused the disease because chestnut lost water during transportation and its disease resistance decreased. They put forward measures to control ecological conditions and suppress diseases, which solved this difficult problem at home and abroad and ensured the export of Chinese chestnut. This research achievement has been highly praised by Japanese counterparts.
Michelle Chen's greatest contribution to agricultural production in China is the development and application of yield-increasing bacteria. According to the concept of plant natural ecosystem, he selected microorganisms that are beneficial to plants and harmful to pathogens, and used them in plants after proliferation to improve plant natural ecosystem and increase crop yield. He also put forward the idea of carrying out plant-microorganism ecological engineering research. The direction he pointed out has clear application significance. Before 1970s, the screening of biocontrol bacteria at home and abroad was mainly carried out from soil and rhizosphere, with the bacteriostatic effect of plate as the index.
The research object is mainly Pseudomonas fluorescens with weak stress resistance. He and his assistants found that there are a large number of Bacillus strains with strong stress resistance on the surface and in vivo of plants, some of which not only have strong affinity with plants, but also have the functions of preventing diseases and promoting plant growth. Therefore, he decided to focus on the study of Bacillus. His decision stems from his strong desire to apply the research results to agriculture, because the research on Pseudomonas fluorescens abroad is difficult to be commercialized on a large scale because of its weak resistance. Regarding the screening method of beneficial microorganisms, he emphasized the use of living plants, because only this kind of microorganism is beneficial to the growth and development of plants, which is what we need; Judging its effectiveness is a complex problem. Michelle Chen believes that the field experiment method of field multi-point comparison experiment and plot comparison experiment can reduce the influence of small area difference of soil, and has the advantages of being visible to production departments and producers, strong in demonstration and easy to understand and accept by the masses. In order to master the first-hand information, Michelle Chen personally went to various provinces for investigation and testing, especially after 1986, when experts conducted on-site evaluation meetings on the application of yield-increasing bacteria in rice, cotton, wheat, rape, peanuts and other crops in different provinces and cities, he personally went to the site for investigation. At this time, he was over 70 years old, and had to walk on the ridge with crutches because of softening bones. Peer leaders, experts and farmers were all moved by his spirit.
After the successful field trial and demonstration of yield-increasing bacteria, in order to apply this scientific research achievement to agricultural production on a large scale as soon as possible, he actively reported to the leaders through various forms, held training courses for technicians all over the country, published a newsletter on yield-increasing bacteria, and conducted publicity and technical training. At the same time, he personally presided over the establishment of the "Experimental Research Consortium for Yield-increasing Bacteria" to organize nationwide popularization and application. Through joint efforts, yield-increasing bacteria have played an interesting role in agricultural production. According to statistics, in 1990, when Michelle Chen died, the yield-increasing bacteria had been used on 54 kinds of crops in 30 provinces, municipalities and autonomous regions, with a cumulative area of 2,620 hectares, which achieved good production, economic and social benefits.
In order to make this technology develop continuously and better serve agriculture, he repeatedly stressed the need to ensure the quality of microbial agents. When he was too ill to dictate, he wrote a personal letter to his colleagues who visited him in his hospital bed, showing his sincere heart in serving agriculture.
Michelle Chen's commitment to scientific research and serving agricultural production stems from his love for the motherland and people. He attaches great importance to letters from farmers and answers questions. When he received a letter from the farmer calling him a "loyal friend of the farmer", he said with emotion, "This is my greatest encouragement".