The harm of water hyacinth and its comprehensive control

Water hyacinth scientific name: water hyacinth, also known as water lily. Water hyacinth stems and leaves hang on water, and branches prostrate on water. Flowers for the multi-edge trumpet-shaped, colorful beautiful. The leaves are dark green. Leaves entire, smooth and textured. Fibrous root developed, tiller propagation fast, extensive management, is a good plant to beautify the environment and purify water quality. In suitable growth areas, often due to excessive reproduction, seize the water surface, affect shipping, suffocate fish, endanger health; destroy difficult, difficult to destroy roots. It is a bifacial organism and is not suitable for large-scale cultivation.

Water hyacinth is very fond of fertilizer, especially nitrogen fertilizer. When the nutrient content of water layer is high, the plant is tall, the root system is short, the flowering is few, the reproduction is fast and the yield is high; when the nutrient is low, the plant is small, the root system is long, the leaf color is yellow, the gourd is purple, the flowering is easy and the yield is low. Water hyacinth is thermophilic and can grow in the range of 0 ~40 ℃. It begins to reproduce above 13 ℃, grows faster above 20 ℃, grows fastest at 25 ~32 ℃, grows slower above 35 ℃, and dies gradually above 43 ℃.

Water hyacinth root system absorption is strong, can enrich water nutrients. Fresh grass contains 0.24% nitrogen, 0.07% phosphoric acid, 0.11% potassium oxide, 1.2% crude protein, 0.2% crude fat, 1.1% crude fiber, 2.3% nitrogen-free extract, 1.3% ash and 93.90% moisture. Besides being used as pig feed and compost, it can also be used as an indicator plant for monitoring arsenic pollution in water because of its sensitivity to arsenic. When arsenic concentration was 0.06ppm, water-stained chlorotic spots appeared on the tip of leaves, and then the spots enlarged and the leaves turned yellow. Because it has the function of enriching heavy metals such as zinc, lead, mercury, nickel and cadmium in water and removing suspended substances in water, it can be used to purify domestic sewage and industrial wastewater, but it must properly solve the repollution caused by plant residue decay. It can also be used as an observation plant. But when it grows too much, it often blocks the river and becomes a harmful grass.

Harm and integrated control of water hyacinth

Water hyacinth, also known as water lotus, phoenix sleep lotus, water lotus, etc., is a perennial aquatic weed, usually floating freely on the water surface. The leaves are clustered and the petiole is spongy. It has two reproductive modes: sexual and asexual, and usually it is mainly asexual reproduction, which is propagated through stolons. Under suitable conditions, a new plant can be reproduced every 5 days, and it can also flower and bear seeds and carry out sexual reproduction. The spikes are from lilac to green, and each inflorescence bears about 300 seeds. After the seeds mature, they fall into the water. Seeds can survive for 5 - 20 years in water and germinate and grow along the fluctuation line of river bank water surface under suitable conditions. The suitable temperature for the growth of water hyacinth is 28 - 30 ° C, and there are about 130,000 water hyacinth plants in one mu of water, with a total weight of 18 - 25 tons. Fifty years ago, China, which was in extreme food shortage, introduced water hyacinth from South America and widely bred it in rural ponds in the south as pig feed. In the past 10 years, farmers who have bid farewell to food shortages have stopped fishing water hyacinth. At the same time, industrialization has deteriorated the water quality of rivers and lakes and increased the degree of eutrophication. Therefore, water hyacinth has spread rapidly and has become a disaster. Even from the inland rivers and lakes between villages, it has "entered" the rivers and rivers. Too much water hyacinth will cover the water surface, if not removed in time, it will also hinder irrigation and water flow in flood season. The dense water hyacinth also reduces the penetration of light into the water, affects the growth of benthos, increases the concentration of carbon dioxide in the water, reduces the yield of aquatic products, increases the evaporation of water, and provides a suitable breeding place for mosquitoes. Some scholars list it as one of the "top ten pests in the world." At present, chemical control, biological control, artificial and mechanical salvage and comprehensive control are mainly used to control water hyacinth. Chemical control methods are simple and effective, commonly used herbicides such as Gramoxone, glyphosate and so on. However, herbicides are destructive to water ecosystems, pollute the environment, and cannot remove water hyacinth seeds, and the effect cannot last. Biological control method is to use the theory of ecological balance between plants and natural enemies, introduce natural enemies from the original place of water hyacinth, make them establish populations, and implement long-term control on water hyacinth. Biological control is safe in environment, low in cost and lasting in effect, which is valued at home and abroad. However, it takes 3-5 years or even longer from releasing natural enemies to obtaining significant control effect. The manual and mechanical control method is to salvage the water hyacinth manually or mechanically, and the effect is quick, but when the occurrence area is large, the labor intensity is large. As with chemical control, artificial and mechanical control is difficult to remove seeds from water, and the control effect cannot last. The comprehensive management method is to adopt the above prevention and control measures in a targeted manner, complement each other, and control the population number of water hyacinth in a relatively low state for a long time. Experts believe that if you want to effectively prevent the crazy growth of water hyacinth at present, the key is to purify the water quality and eliminate the environment suitable for its growth; at the same time, water hyacinth also has certain water purification and water blocking functions. Under suitable conditions, one hectare of water hyacinth can absorb nitrogen and phosphorus emitted by 800 people on the same day. Water hyacinth can also remove cadmium, lead, mercury, thallium, silver, cobalt, strontium and other heavy metals from sewage, thus "turning waste into treasure". According to the principle of seeking advantages and avoiding disadvantages, experts have developed three channels for comprehensive utilization of water hyacinth: through fermentation and transformation, improve the protein content of water hyacinth and make feed; make use of the characteristics of water hyacinth containing a large amount of nitrogen, phosphorus and potassium to make organic and inorganic compound fertilizer; extract nutrients from it, process and extract food, health care products, medicines and feed additives. Using water hyacinth to purify sewage is a simple and feasible method with low cost, energy saving and high benefit. Experts said that in the future, the model of using water hyacinth to treat sewage will be implemented, so that sewage and water hyacinth will become valuable resources.