Hydroponics is an important form of soilless culture of flowers. Hydroponics is a kind of nutrient solution cultivation without substrate, which is cleaner and more environmentally friendly than ordinary soilless flowers, with elegant style and strong ornamental value. However, hydroponics with substrate, especially deep liquid hydroponics, has low oxygen content, which often fails to meet the needs of crop roots, leading to root rot and poor growth. In order to solve this problem, horticultural scientists all over the world have taken many measures, such as applying closed-loop flow of nutrient solution to oxygenate water. Although these technical measures have certain effects, it is still quite difficult to realize the stable production of irregular hydroponic multi-variety flowers. At present, only a few flower varieties in the world, such as hyacinthus orientalis and Tulip, have achieved commercial hydroponics. The researchers of Northeastern University in China adopt interdisciplinary science and technology, comprehensively apply plant physiology, plant nutrition and mechatronics technology, and learn from the successful experience of soilless culture technology at home and abroad. After eight years of research, they finally succeeded in developing the factory soilless asexual propagation method of flowers, which solved the problem of flowers from soil culture induction to hydroponics. In June, 2003, 165438+ 10, this technology was officially granted the invention patent by China National Intellectual Property Administration. At present, this patented technology of factory hydroponic flowers has been implemented in Shenzhen and other places. Using this technology, more than 500 varieties of hydroponic flowers in 9 series have been successfully cultivated, including 32 species of pineapple, 5 species of flamingo, 5 species of Orchidaceae, 8 species of fern ornamental plants 10, 8 species of arrowroot, 290 species of foliage plants, 52 species of cactus and succulent flowers, strawberries and raspberries.
Technical points
The patented technology of factory hydroponics flower cultivation is based on deep liquid flowing water cultivation technology, and has made important improvements in nutrient solution preparation, oxygenation scheme, water disinfection treatment and so on.
Formula of nutrient solution Regarding the formula of nutrient solution, Table 1 gives the formula of six common nutrient solutions for hydroponic flowers, such as leaves, flowers, fruits, flamingos, orchids and ferns, with comprehensive nutrition, reasonable proportion and strong pertinence. The formula not only contains a large number of elements of nitrogen, phosphorus and potassium, a mixture of medium elements of calcium, magnesium and iron, and trace elements of manganese, zinc, boron, copper and molybdenum, but also contains a hydroponic rooting inducer and an aquatic inducer. Hydroponic rooting inducer is a new growth regulator to promote plant rooting under hydroponic conditions. Aquatic inducer is a regulator containing adenosine triphosphate, which guides plants to adapt to hydroponic environment. It can promote the movement of inorganic ions in nutrient solution against electrochemical potential gradient, that is, it can increase the active absorption and transfer of nutrients by plants. Although the dosage of these two regulators is not large, they do play an important role in ensuring the normal growth and development of hydroponic flowers, especially in the early stage, which can significantly improve the survival rate of hydroponic plants.
Oxygen-increasing technology In order to solve the problem of low oxygen content in deep-water aquaculture, researchers chose the oxygen-increasing technology combining magnetic physical oxygen-increasing, chemical oxygen-increasing and mechanical oxygen-increasing (see the national invention patent "A method for manufacturing oxygen-enriched drinking water", patent number 001kloc-0/0622.8), so that the oxygen content in water can be 5 ~10 as needed.
Water temperature control About the temperature of greenhouse, for hydroponics, we should not only control the temperature of greenhouse, but also pay attention to the control of water temperature, that is, the temperature of nutrient solution (see Table 2). Controlling the temperature within the physiological temperature range of plant roots can promote the effective absorption of various nutrients by hydroponic flowers, thus promoting the physiological metabolism and growth and development of plants. In order to control the water temperature, nutrient solution culture tanks are generally built at about 100~200mm below the ground. In summer, combined with the fan and water curtain cooling system in the greenhouse, when the outdoor temperature is 35℃, the indoor temperature can generally be reduced to below 30℃, while the water temperature in the culture pond is about 23℃~27℃, so that plants can spend yesterday's summer safely. In winter, the underground pool can make the water temperature 3℃~5℃ higher than the greenhouse temperature, reducing energy consumption and temperature fluctuation. For the northern greenhouse heating in winter, it is also a feasible scheme to heat the hydroponic pond through pipes, which can reduce energy consumption and temperature fluctuation, which is particularly important for the production of hydroponic New Year's Eve flowers.
Leakage of water and fertilizer Because hydroponic flowers are cultivated in an impermeable culture pool, there is no leakage of water and fertilizer, which is an efficient cultivation method of saving water and fertilizer. The nutrient solution should be supplemented and adjusted every week according to the consumption, so that the nutrient solution in each pool can be used continuously for 2~3 seasons. According to estimates, hydroponics saves 65% water and 40% fertilizer than soil culture.
Adjustment of PH value Regarding the adjustment of pH value of nutrient solution, the suitable pH value of most flowers is between 5.8 and 7.0, and the water quality in most places in the south is soft, which is easy to do. For hard water areas in the north, pH can be easily controlled by adding H3PO4 or H2SO4 (through dilution) regularly, so these areas (such as Beijing) can also produce high-quality hydroponic flowers.
Hydroponics is a process of inducing the formation and normal growth of plant water roots in nutrient solution, so the formation and growth of water roots are the core of this technology.
First of all, different plants have different difficulties in forming water roots. Herbs are fast and easy, woody plants are slow and difficult, plants with large cell gaps are easy, and slow growth is difficult to make cells closely arranged. Wet terrestrial plants are easy, such as Araceae, and drought-tolerant terrestrial plants like peach trees are more difficult. Different plants have different forms of water rooting, but their laws are similar. Compared with terrestrial root system, water roots are mostly fibrous roots, and root hairs are less or degraded. At this time, the water environment causes physiological changes in plants.
Then creating a suitable water environment is our technical focus. Only in a suitable water environment can the continuous formation and development of aquatic roots be promoted. For example, dissolved oxygen in water is a necessary condition for root respiration, and once oxygen-deficient water takes root, it will be inhibited or even browned and rotted. Therefore, it is necessary to detect and control the oxygen in the process of mutation in real time.
In addition, proper water temperature, proper nutrient solution concentration and water level will affect the cultivation of water roots, which should be realized by computer control. These technologies are the technical core of all plant hydroponics, and it is difficult to realize water root culture without computer control, especially for mutant plants.
Aquatic mutagenesis technology of plants
Plant aquatic mutagenesis technology is a technology that uses modern physical technology, computer technology, control technology and biotechnology to make physiological, biochemical and mutagenic changes to plant roots, so that they have strong adaptability to water environment and can be induced into aquatic roots that are completely suitable for water environment growth.
The difference between water rooting and soil rooting
Water rooting: thin, white (some plants are brown), rootless, thin-walled, with aerated tissue;
Soil hair roots: thick, hard, dark in color, hairy, thick in wall, tightly ventilated and degraded.