Plant physiology is a part of botany. But it can also be regarded as a branch of general physiology. Protein, sugar, fat, nucleic acid and other basic components of plants and their metabolism are similar to other organisms (animals, microorganisms). However, plants themselves have some unique characteristics, such as: ① Solar energy can be used to synthesize organic matter from CO2 in the air and water and minerals in the soil, so they are the original producers of almost all organic matter on the modern earth. (2) Plants are rooted in the soil, and their lifestyles are fixed, so there is not much room for pursuing advantages and avoiding disadvantages. They must be able to adapt to local environmental conditions and evolve tolerance and resistance to adverse environments. (3) There is no fixed boundary for the growth of plants. Although some tissues or cells die, they can still regenerate or renew and continue to grow. ④ Plant somatic cells are totipotent. Under suitable conditions, a somatic cell can become a complete plant after growth and differentiation. Therefore, plant physiology has important practical and theoretical significance.
[Edit this paragraph] A brief history of development
Generally speaking, the origin of plant physiology can be traced back to the experiment of Dutch Van Elmont in the 6th century. He planted a willow branch in the flowerpot and watered it every day. Five years later, the weight of willow branches increased by 30 times, while the weight of soil in the flowerpot decreased slightly, so he thought that the material source of plants was not soil, but water. This is the first time to study the physiological phenomena of plants by experimental methods. By the end of18th century19th century, J. priestley in Britain and J. Ingenhaus in the Netherlands had discovered the main links of photosynthesis, which proved that green plants could synthesize organic matter from CO2 in the air and water in the soil, and release O2 under light. Italian Marcello Malpighi, Englishman hales, Frenchman Boussingault, German Justus von Liebig and Englishman Darwin discovered or expounded the phenomena of material transportation, water absorption and transpiration, nitrogen nutrition, mineral absorption, plant sensitivity and plant movement. With the accumulation and systematization of knowledge, in 1800, J. Seneby of Switzerland wrote and published the first plant physiology in the world.
/kloc-at the end of 0/9 century, J. von Sacks of Germany first opened a special course on plant physiology. With the efforts of him and his students, plant physiology became a specialized subject independently from botany. Especially in the 1920s and 1930s, due to the progress of physics, chemistry, microbiology and general physiology, as well as the rise of biochemistry and biophysics, plant physiology went deep into the cellular level. From 1930s to 1940s, it entered the level of organelles, such as analyzing the mechanism of respiration and photosynthesis with isolated mitochondria and chloroplasts. Since 1950s, it has become an aspect of molecular biology to go deeper into the combination of macromolecules, the structure and function of biofilm, the function of isolated enzyme system and even the mechanism of electron transfer system. As far as the time scale of the research is concerned, it has been shortened from five years in the Vermont experiment to several days and hours, and now it has been shortened to seconds, milliseconds (10-3 seconds), microseconds (10-6 seconds), nanoseconds (10-9 seconds) and even picoseconds (65438+3
The other end of the development of plant physiology is to go macro. From the study of individual plants to the study of groups and communities. Because no matter in artificial farmland or nature, plants are gathered together, and few single plants survive; Agricultural production is also often based on land area, not individual trees. Therefore, we must pay attention to the structure and activities of groups; The interaction and relationship between plants and the external environment and other plants; Ventilation and light transmission, soil water and fertilizer supply, symbiosis and mutual exclusion phenomenon and mechanism In this way, plant physiology is adjacent to ecology, and two branches of plant physiology ecology and eco-physiology have been developed.
The research work of modern plant physiologists has partially entered the quantitative stage, and after introducing new technologies such as computers, mathematical simulation of plant physiological activities has begun. Because plants are almost the only members who absorb and transform solar energy, plant physiology is also indispensable when discussing the origin of life, energy development, space navigation, alien life, bionic simulation and other issues.
As early as 3000 years ago (BC 14 ~ BC 1 1 century), there were records of agricultural cultivation and fertilization involving plant physiological activities in Oracle Bone Inscriptions. Later, it was elaborated in Fan Sheng Zhi Book (about 100 BC), Qi Yaomin Book (533 ~ 544 years), Wu Kai in Tiangong (1637 years) and other monographs. Song (1587 ~ 1660), the author of Heavenly Creations in the late Ming Dynasty, once said in Qi Lun written by his contemporaries with Fan Ermeng: "Push the ground one grain at a time, the small one is covered with a canopy, and the big one is covered with a dried cow tree. What is the original geometric shape of this grain? The rest are gasified. " It has been clearly pointed out that plants use air to grow.
China's experimental plant physiology was introduced from abroad. In the early 1920s, Qian He began to teach plant physiology after studying abroad. Li Jidong has set up plant physiology laboratories in Nankai University and Tsinghua University since 1927, Sun Yat-sen University, Central University, Zhejiang University and Academia Sinica since Luo Zongluo193, and Tang Peisong 1933 in Wuhan University and Tsinghua Agricultural Research Institute. Their research results are still often cited by foreign literature. The first and second generation students they trained are now the main force of this subject in China. During the 1930s and 1940s, due to the turmoil in War of Resistance against Japanese Aggression and postwar China, universities and research institutes were scattered everywhere, and plant physiology, like other sciences, was not fully developed, with only 30 professionals in total. After 1949, the research and teaching of plant physiology have developed rapidly, and work has been carried out in various fields related to plant physiology, especially photosynthesis, and remarkable results have been achieved. At present, Shanghai Institute of Plant Physiology of China Academy of Sciences is located in China. Plant physiology research rooms (groups) or teaching and research rooms (groups) are set up in plant research institutes in major regions and universities; Agriculture, forestry and other departments have set up crop physiology research rooms (groups). Since the establishment of 1963, the China Society of Plant Physiology has held four national congresses and published a collection of papers. Many provinces, municipalities and autonomous regions have successively established local plant physiology societies. China Plant Physiology Society sponsored the Journal of Plant Physiology and plant physiology communications, and Beijing Plant Physiology Society sponsored the Journal of Plant Physiology and Biochemical Progress.
[Edit this paragraph] Subject content
Modern plant physiology research is generally divided into the following aspects: 10.
① Photosynthesis. Special functions of green plants. They have photosynthetic pigments and can absorb sunlight. After the pigment is excited, the charges are separated, and the electrons are transferred through a series of carriers, which causes the redox reaction: at one end, the water molecules decompose and release oxygen; The other end reduces coenzyme II, and at the same time causes proton (hydrogen ion) transfer, resulting in potential difference and hydrogen ion concentration difference inside and outside thylakoid membrane in chloroplast, which promotes the synthesis of adenosine triphosphate (ATP). In this way, light energy is converted into chemical energy in reducing coenzyme II and ATP, and finally CO2 inhaled from the air is fixed and reduced to carbohydrates through a series of enzyme reactions.
② Plant metabolism. Can be divided into two major aspects. On the one hand, it is anabolism-the relatively simple organic matter produced by photosynthesis is transformed into more complex organic matter including macromolecules such as protein, nucleic acid, enzyme and cellulose. Through a series of enzyme reactions, it constitutes a part of plants; Or store starch, sucrose, oil and other substances to provide energy for their life activities. On the other hand, catabolism-hydrolysis (or phosphorolysis) of macromolecules into simple glycophosphoric acid, and then glycolysis to form pyruvate, while producing a small amount of ATP and reduced coenzyme (NADH or NADPH).
③ Plant respiration. Like animals, plants breathe, but there are no respiratory organs that specialize in gas exchange like gills and lungs. Reduced coenzyme or several simple organic acids formed by catabolism undergo a series of electron transfer (respiratory chain), and finally the inhaled oxygen is reduced to water. Electron transfer and terminal oxidation are carried out in mitochondria. Electron transfer is accompanied by the formation of ATP, which provides energy for various life activities.
④ Plant water physiology. Plant life needs a lot of water, only a small part of which is used for photosynthesis and metabolism, and most of it is evaporated from leaves when stomata (stomata) are opened and photosynthesis is carried out under sunlight. Terrestrial plants adapt to transpiration water demand and evolve various structures. Developed roots absorb water from soil and transport it to leaves and other aboveground organs through xylem vessels or tracheids. When entering the atmosphere, pores can control the loss of water. Plants in arid areas have special structures and metabolic patterns, which can reduce transpiration.
⑤ Plant mineral nutrition. Besides carbon dioxide and water, plants need many chemical elements. Nitrogen (N), phosphorus (P) and potassium (K) are in great demand and are often applied as fertilizers in agriculture. The next requirements are calcium (Ca), sulfur (S), magnesium (Mg) and iron (Fe), which are essential components of living matter in plants, including some enzymes. In addition, some trace elements are needed, such as manganese (Mn), zinc (Zn), boron (b), copper (Cu), molybdenum (Mo) and so on.
⑥ Transportation in plants. Plants have no blood circulation system, but the photosynthetic organs (leaves) that make organic matter are located on the ground, the roots that absorb inorganic nutrients and water in the soil are underground, and the reproductive organs (flowers, seeds, fruits, etc.). ) have to get a supply of nutrients from them. In order to meet the needs of material transportation between aboveground and underground parts and between organs, plants have evolved two special channels, namely xylem and sieve tube. Xylem mainly transports water and mineral elements dissolved in it, and sieve tube mainly transports organic matter.
⑦ Growth and development. Growth is mainly through cell division and expansion, and development is through cell differentiation to form different tissues and organs. The growth and development of plants are restricted by internal factors and external environment, which has certain stages and seasonality. Plants in areas with obvious changes in cold, warm, rainy and dry seasons often have dormancy periods. Seeds are mostly formed before the arrival of winter or dry season, and spend the harsh environment in a dormant state. The transition from vegetative growth (growth of leaves, stems and roots) to reproductive growth (differentiation, flowering and fruiting of flower buds) is often accompanied by annual changes in the natural environment. Plants have a series of mechanisms to feel environmental changes, and photoperiod phenomenon is one of them. Plant cells have great totipotency. After being separated, cells in many parts of the body can be dedifferentiated and grow into callus in artificial culture medium. Under appropriate conditions, it can be redifferentiated to form roots, stems, leaves and other organs, and even grow into complete plants.
8 plant hormones. Plants have no nervous system, and the physiological activities between organs are mostly regulated by some special chemicals except the supply and demand of nutrients. These chemicals are called phytohormones, which are formed in some parts and transferred to other parts to play a role. For example, auxin, which was first discovered, forms at the top of the growth and promotes the elongation of the cells below. Subsequently, many other hormones were discovered, such as abscisic acid, gibberellin, cytokinin and ethylene. In addition to regulation by chemical substances, plants can also have rapid physical information transmission, such as potential changes.
Pet-name ruby resistance. Different plants have great differences in tolerance and resistance to adverse environment, some can survive under extremely dry conditions, and some can resist low temperature. There are also great differences between varieties. In nature, the distribution of plants in different habitats depends largely on their resistance to adverse environment. In agricultural production, expanding crop planting and understanding the physiological mechanism of stress resistance will help to take measures to improve stress resistance, or provide physiological indicators for screening stress-resistant varieties in breeding.
Attending plant movement. Lower plants living in water, some of which have flagella and other special organs, can swim and phototaxis. Although terrestrial plants have a fixed position, they are not completely motionless. Roots have directionality (gravity) and leaves have phototropism. Growth movement is called growth movement. Some plants can do mechanical exercise, such as water lilies, whose white flowers open in the sky and close at night; The compound leaves of Albizia Albizia closed at night; Mimosa and insectivorous plant Nepenthes, etc. , faster.
[Edit this paragraph] Application and prospect
Plants are the main organisms that use solar energy to synthesize organic matter on the earth. Their physiological activities are of great significance to human beings.
Agriculture focuses on cultivating plants. In order to control the life activities of crops, increase the yield and improve the quality, it is necessary to understand the physiological activities of plants. For example, plant mineral nutrition knowledge is the basis of rational fertilization and fertilizer industry; The analysis of plant water relationship can provide a scheme for irrigation; Understanding the demand of plants for photoperiod or vernalization can not only explain how meteorological conditions determine phenology and predict the possibility of successful introduction, but also control flowering period through artificial lighting or shading and vernalization treatment. The discovery of hormones enables people to synthesize, promote cuttings to take root, sparse flowers and fruits, induce, strengthen or break dormancy, and promote or inhibit growth. Improve the output and quality of agricultural products; Herbicide is a high-dose application of growth regulator, which saves a lot of weeding work; Studies on physiological mechanisms such as photosynthesis, metabolism, transportation and resistance provide screening indicators for seed selection and breeding. The development of tissue culture, cell culture and other technologies has opened up a new way for speeding up pure breeding, improving and creating new species. At several international conferences on agriculture and food, 10 has put forward many urgent research tasks, including: ① photosynthesis and yield increase; ② Biological nitrogen fixation; ③ Mineral absorption; ④ Resistance to adverse environment; ⑤ Resistance to competitive biological systems; ⑥ The growth and development of plants and hormones belong to the category of plant physiology. Other projects, such as genetic engineering, cell engineering, mycorrhiza and soil microorganisms, air pollution and pest control, are also related to plant physiology. Therefore, plant physiology is an important knowledge base of agricultural modernization.
Environmental protection and pollution prevention also involve plant physiology research. For example, using plants to fix sand, prevent wind and purify water sources. In 1970s, it was pointed out that due to industrial development, the amount of fossil fuels burned was large, and C in the air increased significantly, which affected the climate. Increasing carbon absorption by photosynthesis is one of the countermeasures.
Recently, the outstanding problem is the development of new energy. Because the fossil fuel resources preserved in ancient times will be exhausted one day, all countries attach great importance to seeking renewable energy. At present, the most important way to capture and convert solar energy on the earth is the photosynthesis of green plants, which can be fixed at 3× 10 2 1 joule every year. Although it is less than one thousandth of the total solar energy on the earth, it is 10 times the annual energy consumption of the world. The proposed methods are as follows: ① Making biogas from existing plant residues, which has been popularized and applied in many places in China; (2) Fermentation of plant products to produce alcohol has been produced on a large scale in some countries; (3) Planting oil-producing and hydrocarbon-producing plants on land unsuitable for cultivation to extract fuel; ④ Using algae or isolated chloroplasts to produce hydrogen under illumination; ⑤ The extracted chlorophyll and artificial inorganic semiconductor substances are used to simulate moisture and explain hydrogen evolution, which are developed by plant physiology research. Solar energy is inexhaustible. If it can be used to produce hydrogen as fuel, it can be reused after oxidation and combustion without causing pollution.
[Edit this paragraph] Results and analysis
1. Statistical Analysis of National Excellent Courses of Plant Physiology
At present, there are four national top-quality courses in plant physiology, and the main development time is from 2003 to 2004 or even earlier. No new excellent courses have been approved in the past two years. Courseware types are mostly in PPT format, but also in Authorware, Shock Wave flash or PDF format.
2. Statistical analysis of other provincial and university-level excellent courses in plant physiology.
Baidu search results show that as of July 2008, there are 18 universities in China that have built provincial and school-level excellent courses in plant physiology, including 4 comprehensive universities, 8 agricultural and forestry universities and 6 normal universities. Through the comparative analysis of these courses, we find that these courses are basically developed according to the requirements and formats of national top-quality courses. The main modules of the course generally include: course overview (introduction), teaching team (lecturer), teaching resources (theory course, experiment course, syllabus, exercise training, etc. ), introduction of teaching methods and means, teaching conditions, teaching effects, test questions and teaching videos.
These 18 courses are in various forms, both static and dynamic. There are both self-developed teaching systems and teaching support systems based on commercial development. However, the main course modules, such as lesson plans, courseware and question bank, are still provided in a single form. Teaching plans and question banks are still mainly provided in Microsoft Word document (DOC format) or hypertext (html format), and most of the teaching courseware as the core content of teaching is still presented in PPT format, and only a few courses are developed with interactive software such as AW or Founder Aosi.
From the overall situation of four national-level top-quality courses of plant physiology and other provincial-level and school-level top-quality courses of plant physiology, static website technology and dynamic website technology each account for about half, and the types of courseware are relatively diverse, but more are provided in the form of Powerpoint(PPT). At present, it is a convenient, fast and effective way to make electronic courseware with PPT manuscripts. As a demonstration tool, PPT courseware is often displayed page by page according to our pre-designed order, showing a single linear structure. Although PPT has hyperlink function, the interactivity of courseware made with multiple slides or even the whole class often cannot meet our needs, which may affect the teaching effect to some extent. The advantage of this software is that it is easy to learn and use, and the technical requirements for producers are relatively low. So far, PPT is still one of the first choice courseware development software, even in the national top-quality courses.
Up to now, although the top-quality course of plant physiology has been built for more than five years, we still need to make more efforts to make the course reach a new level. The author thinks that we should make breakthroughs in the following aspects: ① The platform for courseware development should be more intelligent and diversified; ② The content of courseware should be more substantial. At present, quite a few courses are still at the electronic level of teaching materials, and the courseware is mainly composed of words and pictures, lacking effective organization; ③ The intelligence of exercises (papers and topics) is not enough. At present, the exercises of all excellent courses are basically provided directly in DOC format or html format, and there are few systems for intelligently generating and judging test papers.
The answer to the online training platform is in official website, and you can also find the answer on the browser website. Xiamen Net Softwa