How to judge the difference in the mortality rate of plants under extreme drought conditions?

Drought is the most common threat to plant growth and development worldwide. It is generally believed that the collapse of water transport, the reduction of water transport to the point of complete loss of transport capacity, is the key cause of the death of flowers and trees caused by drought. The hydraulic properties of plants related to water transport are expected to be used to analyze the main manifestations of plant extremes in response to drought, <>

As everyone knows, because extreme droughts under natural conditions are usually unpredictable, many scientific studies are carried out under manipulative standards. In addition, due to the difficulty of measuring hydraulic properties, the number of populations involved in previous scientific studies is small, and it is not possible to discuss the differences between different acting populations to a relatively large extent.

In the valley region of southwest China, the climate is dry and the air is dry, and the growth and development of the unique "valley-type Sawana plant community" has typical xerophytic characteristics. The coexistence of woody plants with different living and deciduous habits in the hot and dry valleys provides an excellent site for scientific research on the response of different populations of plants to drought. In the extreme drought of 2015, many plant terminals in the hot and dry valley withered and some of the ground died.

For about 3 years, the scientific research elite team has continuously tested the physiological changes of plants in different parts of the drought, the withering of individual peripheral nerves and the death of some people on the ground after the drought, and at the same time, the system software science has studied the hydraulic characteristics of the branches and leaves of this plant. The results showed that the leaves and branches of plants in the dry-hot valley of the Yuanjiang River showed strong drought tolerance and working ability, but there were huge differences between species.

The key driver of the hydraulics of the branches and leaves is the defoliation habit of the plant leaves (evergreen, early and semi-deciduous in the dry season) rather than the living (lianas, shrubs, shrubs). Plants with the same deciduous habits and different microbial types mostly showed the characteristics of convergence and integration. Semi-deciduous plants and shrub species have better branch wilting and upper ground mortality than other populations.

Scientific research emphasizes that hydraulic properties can better analyze the main performance of plants in extreme drought, and the analysis should take into account the hazards of defoliation habits and life.

It can be judged according to the environment in which the plant is generated, the growth time of the implant, and the growth state of the plant, so that the death rate can be determined.

You can tell by their morphology. If it can survive in a drought situation, it indicates that it is relatively drought resistant.

This is judged according to the specific situation, and then you can look at the condition of the soil, and you also need to look at the growth and development of the plant.

You can tell by its appearance that plants with a high mortality rate are prone to wilting.

Cactus, Mongolian leeks and other plants. Cacti are recognized as drought-tolerant plants, and the inside of the plant is very watered, even if it is not watered for a long time, it will definitely not wilt and die. The common name of the Mongolian leek is shallot, and it is characterized by its very fast growth, and as long as there is a little rainfall, it can reproduce quickly.

Yaoxihua, Shengshihua, Giant Pillar, Baobab, and Chitose Orchid are all very tenacious in vitality.

Why is it not suitable to fertilize plants under drought conditions?

The reasons why seedlings cannot be fertilized due to drought are:

Drought means that there is less water in the soil, that is, the water potential is low, if fertilization will reduce the water potential in the soil even more, the water potential in the plant is relatively high, the water in the body will flow back into the soil, and the plant will die due to severe water loss. Therefore, seedlings cannot be fertilized when they are dry.

Answer D analysis: The knowledge point of this question is the adaptation of organisms to the environment, which can be cut from the aspect of how organisms adapt to the characteristics of the environment

Answer: The morphological structure of organisms is always adapted to the living environment In the dry environment of Zhenmin, there is a lack of water, and having a well-developed root system can improve the water absorption ability of plants; The main organ of plant transpiration is the leaf, so it has a small leaf area, which can reduce transpiration and reduce water loss. The fleshy stem with hypertrophy can store a lot of water, improve the water retention capacity of the plant, and adapt to the arid environment The transpiration of the plant is mainly carried out through the stomata on the leaves, and the number of stomata is large, the transpiration is strong, and the water lost is more, so it is not suitable for the arid environment Therefore, the answer d is in line with the topic

Therefore, the mill calendar is selected: d

Comments: The key to answering such questions is to understand the characteristics of plants in water absorption, water retention, and transpiration reduction

The most direct impact of drought on plants is to cause protoplasm dehydration, which is the core of drought damage, which can cause a series of injuries, mainly as follows:

1) Change the structure and permeability of the membrane The cell membrane loses its semi-permeability under drought damage, causing the extravasation of intracellular amino acids and carbohydrates.

2) Disrupt normal metabolic processes e.g., photosynthesis significantly decreases or even stops; Respiration is enhanced by water shortage, which decouples oxidative phosphorylation and decouples, and energy is mostly consumed in the form of heat, but there are also water shortages that weaken respiration, which affects the normal biosynthesis process; Protein decomposition is strengthened, the protein synthesis process is weakened, and proline accumulates in large quantities; Nucleic acid metabolism is disrupted, and drought can reduce the content of DNA and RNA in plants. Drought can cause changes in plant hormones, most notably an increase in ABA levels.

3) Abnormal distribution of water In times of drought, young leaves generally absorb water from old leaves, which causes old leaves to wither and die. The functional leaves with strong transpiration take water from meristem and other young tissues, causing some young tissues to lose water seriously and develop poorly.

4) Mechanical damage to protoplasts During drought, cells are dehydrated and shrink inward, damaging the structure of protoplasts, such as sudden rehydration, causing the uncoordinated expansion of the cytoplasm and the wall, tearing the protoplasmic membrane, and leading to the death of cells, tissues, organs and even plants.

Measures to improve drought resistance:

The breeding of drought-resistant varieties is the most fundamental way to improve the drought resistance of crops, and the following measures can also be taken to improve the drought resistance of plants

1. Drought resistance exercise: Moderate drought treatment should be carried out at the seed germination stage or seedling stage, so that the plants can undergo corresponding changes in physiology and metabolism and enhance their ability to adapt to drought. In the cultivation of crops, farmers use the "squatting seedling" method to improve the drought resistance of crops, that is, to give moderate water shortage treatment at the seedling stage of crops to inhibit the growth of aboveground parts, so as to exercise their ability to adapt to drought.

2. Rational fertilization Rational application of phosphorus and potassium fertilizers and proper control of nitrogen fertilizers can improve the drought resistance of plants. Phosphorus promotes the synthesis of organophosphorus compounds, improves the hydration of protoplasms, and enhances drought resistance. Potassium can improve carbohydrate metabolism in crops, reduce the osmotic potential of cells, promote stomatal opening, and facilitate photosynthesis.

3. Application of growth retardants and anti-transpirants In recent years, the application of growth retardants to improve the drought resistance of plants has achieved certain results.

4. Water saving, water harvesting, and the development of dry farming Dry farming refers to agricultural production technology that is less dependent on irrigation, and its main measures are to collect and preserve rainwater for later use, use different root zones to alternately irrigate, use fertilizer to transfer water, improve water use efficiency, use plastic film to cover and conserve moisture, grasp the law of crop water demand, and use water rationally.

For drought, it depends on the degree. The so-called drought refers to the phenomenon of water deficiency in the plant body, the leaves of the plant will droop, if the water is not in time, wilting will occur, if the drought is severe, the plant is easy to die because of the formation of permanent wilting. Of course, a small degree of drought is a manifestation of transpiration, forming a transpiration pull, which plays an important role in the transport of organic matter and water in the plant body, and promotes the growth of the aboveground part, that is, the so-called crown ratio increase.

Measures:1Drought resistance exercises for plants, i.e., keeping plants in a certain arid soil, will gradually adapt and develop resistance to drought 2The application of phosphorus and potassium fertilizers, and the application of less nitrogen fertilizers, will promote the development of the root system of plants and enhance the absorption of water.

In arid environments, water is scarce, and having a well-developed root system can improve the water absorption capacity of plants; The fleshy stems with hypertrophy can store a lot of water, and the leaves are needle-shaped to reduce water evaporation; It has a thick cuticle that can reduce the transpiration of water, improve the water retention capacity of the plant, and adapt to the arid environment

Therefore, d

Answer C The permeability of the soil in the waterlogged land will decrease, due to the lack of oxygen affecting the respiration of the root cells, the cells will suffocate and die, and the dead cells will no longer have the ability to absorb water, then the plants will have the symptoms of water shortage, and even wilt and die.

D test question analysis: lack of water in arid environment, with a developed root system can improve the water absorption capacity of plants, with a thick fleshy stem can store a lot of water, with a thick cuticle can reduce the transpiration of water and improve the water retention capacity of plants, and adapt to the arid environment, the leaf area is large, the transpiration effect is large, and the lost water is not suitable for the arid environment.

Comments: This question is a basic question, which is easy, and the key to solving such questions is to understand the characteristics of water absorption, water retention, and transpiration reduction of plants.