N1 - Stress tolerance in plant

For example, water shortage stress is often associated with salinity stress at the roots or high temperature stress in the leaves.. 2.1 Drought tolerance water stress tolerance 2.1.1 Dry

VIETNAM GENERAL CONFEDERATION OF LABOR

TON DUC THANG UNIVERSITY FACULTY OF APPLIED SCIENCES

SEMILAR REPORT ON PLANT PHYSIOLOGY

STRESS TOLERANCE IN PLANT

Instructor: TRAN THI DUNG Implementer: LE NGOC THANH TRUC 617H0093

PHAM QUOC KHANH 61703128

HO CHI MINH CITY, 2022

Table of Contents

1 OVERVIEW OF STRESS TOLERANCE IN PLANTS 1

1.1 Notion 1

1.2 The properties of stressors 1

1.3 Plant response to stress 1

2 PLANT-RESISTANT PHYSIOLOGY 2

2.1 Drought tolerance (water stress tolerance) 2

2.1.1 Dry types of environment 2

2.1.2 The harmful effects of the tree's drought 3

2.1.3 Drought tolerance of trees 3

2.1.4 Drought-tolerant forms 4

2.1.5 Measures to improve the drought tolerance of trees 5

2.2 Heat resistance 6

2.2.1 Harmful effects of high temperatures 6

2.2.2 Heat resistant properties 7

2.2.3 Measures to improve heat resistance 7

2.3 Cold resistance of the tree 8

2.3.1 Harmful effects of low temperature 8

2.3.2 Characteristics adapted to low temperature 9

2.3.3 Measures to improve cold resistance 9

2.4 Salt tolerance of plants (salt stress) 9

2.4.1 Harmful effects of salt stress 9

2.4.2 Salt-tolerant forms 10

2.4.3 Measures to improve salt stress tolerance 11

2.5 Pest tolerance 12

2.5.1 Pathogenic microbial characteristics 12

2.5.2 Harmful effects of pathogenic MICROBIAL 13

2.5.3 Disease tolerance (immunity) 14

2.5.4 Measures to improve the immunity of the plant 15

1 OVERVIEW OF STRESS TOLERANCE IN PLANTS

1.1 Notion

Plant resistance (also known as stress) refers to external factors that adversely affect plants and plant responses to stressors It is the resistance of plants

to adverse environmental conditions

The agents that cause stress to plants are dry, drought, cold, hot, salty, air pollution Stressors create the characteristic adaptability of plants

1.2 The properties of stressors

Stress can drastically reduce the growth and growth of crops, leading to reduced crop yields Therefore, understanding the mechanisms of harm of stressors

as well as the adaptive responses of plants plays a very important role in cultivation

Stressors can act separately, but some agents can work together on plants For example, water shortage stress is often associated with salinity stress at the roots or high temperature stress in the leaves

The stressor for this plant may not cause stress to other plants

1.3 Plant response to stress

The plant body's response to stressors can be specific or non-specific Specific reactions are reactions that are contrary to changes according to normal natural laws Non-specific reactions are reactions that follow the normal laws of nature

Plant stress resistance such as the formation of adaptive characteristics is a specific self-defense response Depending on the characteristics and intensity of the stressors, the plant will have very different responses The factors acting with low intensity are not enough to cause stress, the tree will still respond normally When agents acting with intensity to the level of stress of the body of plants appear to

react in self-defense, new characteristics that were not previously available, are stress-resistant characteristics

There are two forms of resistance: individual resistance to each element and resistance to many factors that bind stress simultaneously

When the plant body creates properties adapted to adverse environmental factors, those elements are transformed into normal living conditions of the plant, which are necessary for the growth and development of the plant

2 PLANT-RESISTANT PHYSIOLOGY

Plants are variable organisms so the environmental temperature has a great influence on the living activity of plants The physiological temperature amplitude

of the plant is about 1-45°C However, there are also groups of trees that live at higher temperatures (heat-resistant trees) or low temperatures (cold-tolerant trees)

2.1 Drought tolerance (water stress tolerance)

2.1.1 Dry types of environment

The term is the phenomenon that occurs when the plant is lacking water, the amount of water sucked into the plant does not compensate for the amount of evaporated water that causes the plant to lose water balance and wither This is also

an important cause of reduced crop yields, which have three types of drought:

 Land drought: occurs when the amount of water stored for the plant to absorb in the soil is depleted so the plant does not suck up enough water and loses water balance

 Air drought: when the air humidity is too low, the plant's steam drainage process is too strong, which can lead to a water imbalance in the plant

 Physiological drought: the physiological state of the plant does not allow the plant to draw water although in the environment there is no shortage

of water, due to the soil temperature being too low or the concentration of salt in the environment being too high

If the land limit is combined with the air limit, the level of harm to the cause increases many times

2.1.2 The harmful effects of the tree's drought

Causes the phenomenon of primary shrinkage that causes the plant to wither Primary contraction occurs when the concentration of water in the environment is too high or due to water stress causes the water in the cell to escape, so the neuron is shrinking, the volume does not narrow When the water-deprived environment is too long, the cell dehydrates without shrinking, the tissue becomes weak and withering occurs

Drought interferes with the transport of water in the wood circuitry, the water supply is not enough during the night to hydrolyze tissues that have been deprived

of water during the day, the suction feathers damage the outer layer When there is a lack of water, there will be many air bubbles in the wood circuit that disrupt the continuity of the water column so it is not pushed up continuously

Drought thickens the cutin layer on the leaf surface reducing the drainage of steam through the epidermis

Drought drastically reduces photosynthesis, when the water content in the leaves remains about 40-50% of the photosynthesis of the leaves is stalled

Drought interferes with the growth of trees, lack of water reduces physiological activities especially photosynthesis, so it reduces growth and growth, trees slow to grow, productivity decreases

2.1.3 Drought tolerance of trees

There are many different forms of adaptation to drought conditions and water stress:

Reduce the leaf surface and drain the steam Lack of leaf water grows slowly, the leaf surface narrows Water stress closes the gas through the effects of abscisic acid and stimulates deciduousness due to the effects of ethylene

The leaves transform morphologically in the direction of reducing steam drainage Thick, hairy wax layer on the leaves, reducing the number of giant gases, needle-shaped leaves

Photosynthesis decreases less than reduces leaf growth when water is lacking, causing the majority of photosynthetic products to be transferred to the roots causing the roots to thrive When there is a lack of water the soil layer is often dry and hard, so the roots tend to grow in depth Thus, the development of roots is a form of adaptation to drought

The ability to adjust osmotic pressure to maintain the water balance between cells and the environment is also a form of plant adaptation to drought When the soil is dry, the osmotic pressure of the soil solution is very high, the plant that wants

to suck water must adjust for the osmosis pressure to rise higher than the pressure of the environment Regulating pressure by accumulating soluble substances in the cell increases the osmotic pressure of the cell fluid, the accumulation of ions for regulation occurs mainly in noncellular so that the ions do not affect the activity of enzymes in the cytometer

For the CAM plant group to adapt to the water-deprived environment is the storage of water in the plant (succulent plant), the use of water-saving (phosphorylation of false rings) and changes in the mechanism of opening and opening the situation gas, opening only the giant gas at night and closing during the day thus very saving water

2.1.4 Drought-tolerant forms

There are many forms of water stress adaptation such as aquatic plants, monographic trees and the group of drought trees

 Group of aquatic plants (hydroohyta): living in an aquatic environment.

 Mesophyta: living in an environment with proper humidity, without water

this group of plants will grow and grow slowly

 Group of birth trees (xerophyta): living in an environment of severe water

shortage There are four different forms of drought

o Succulent plants (xuculen): both drought-tolerant and very hot, can

live in areas with a prolonged hot dry climate The form of adaptation is leaf reduction, spreading roots, water reserves in the plant, cutin layer on the thick leaf surface reduces steam drainage, high viscous concentration and economical use of water, some plants only open the gas at night (CAM group)

o Hemi xerophit: moderate drought tolerance The form of

adaptation is the root developed to suck up strong water, steam drainage also occurs strongly, viscosity is not high

o Real drought trees: high drought tolerance, high viscosity and elasticity of high virginity, high osmotic pressure, weak steam drainage process, economical water use

o Plants do not regulate the water mode: the group of plants has a special adaptation to the water regime in the environment When dry this plant group lives in a latent state or underground life When encountering a sufficiently watery environment they conduct the process of growth, develop strongly and quickly end the life cycle

2.1.5 Measures to improve the drought tolerance of trees

In order to improve crop yields in drought conditions, improving the drought tolerance of plants is an important measure There are many measures to improve the drought tolerance of the tree:

 Training the seeds before sowing is the most effective measure Soaking the seeds interspersed with drying the seeds several times before sowing has trained the seed to get used to the lack of water i.e adapt to water stress right at the embryonic stage This measure causes many changes in the virginity, metabolism and physiological activity of the plant occurs in

the direction of adapting to limited conditions, which should give the plant a high drought tolerance

 Choosing drought-tolerant varieties is an important measure Rely on the limited groups of trees available to select those suitable for the conditions

of different geographic regions As a result, we can create a reasonable crop structure for each different ecological region, ensuring proactive response to drought

 Technical measures such as proper fertilization, proper technical care It also contributes to improving the stress tolerance of plants

By appropriate measures, it is possible to increase the drought tolerance of crops that contribute to the maintenance and increase in crop yields in drought conditions

2.2 Heat resistance

2.2.1 Harmful effects of high temperatures

When encountered with high temperatures, it causes protein freezing that leads to damage to the whole essence, most plants do not tolerate temperatures above 50 °C for extended

High temperatures will destroy the organ structures of the cell and the organs

of the plant Mitolate and chlorographic are both damaged affecting respiratory and photosynthesis function, burning leaves reduce the ability to photosynthesis and drain steam When the temperature rises the intensity of photosynthesis decreases faster than the rate of respiration Above the threshold of photosynthesis physiological temperature does not compensate enough muscles for respiration, so gluxit reserves will decrease The imbalance between respiration and photosynthesis

is one of the main causes of harm to the plant

Elevated temperatures lead to high fluidity that changes the structure of the membrane causing the membrane to lose its physiological function, to seep the ions out of the cell In addition, high temperatures also stimulate the decomposition of

substances, especially proteins when sharply decomposed NH3 products accumulate

in cells that are toxic to plants As temperatures rise it also reduces the amount of organic acid and many other important organic compounds due to decomposition

In particular, high temperatures cause respiration to occur strongly but the accumulation of energy through phosphorrylization is limited so most of the heat released during respiration in the form of heat increases the intracellular temperature resulting in the cell being damaged and possibly dying

2.2.2 Heat resistant properties

There are many types of self-defense responses characteristic for adapting to environments with high temperature conditions Each group of trees has a characteristic form of adaptation

For hot drought trees enhance the steam drainage process accompanied by increased wateruction capacity to regulate the body's internal heat

For succulent plants with high virgin viscosity, it is highly heat resistant Many groups of plants thanks to changes in the structure and composition of the substance that can withstand heat The plant groups are high in nucleoprotein and lipoprotein complexes that help the plants withstand high temperatures In particular, this group of plants has the ability to synthesize strong heat shock proteins (HSPs), high levels of HSPs, so the heat resistance is very high

2.2.3 Measures to improve heat resistance

The harmful effects of high temperatures reduce the vitality of the plant thereby reducing productivity, so improving the heat resistance of the plant helps the plant overcome high temperature stresses is an important measure contributing

to improving crop productivity:

 Choosing a plant variety that can withstand high temperatures is an effective measure Through the bank like we can select, breed to create plant varieties adapted to high-temperature environmental conditions,

from which it is possible to build a reasonable crop structure for local, each ecological region

 Training the plant to adapt to high temperature conditions by soaking the seeds before sowing them in cold water then switching to hot water, repeatedly is a highly effective measure Thanks to the high temperature stress from the embryonic stage, it has gradually adapted to hot conditions In the embryo has been modified to adapt to high temperatures, so when the plant grows up if faced with high environmental temperature conditions , it will be less adversely affected

 The coordination with technical measures such as fertilization, fresh pepper, reasonable care it also contributes to helping plants withstand high temperatures to maintain the growth and development process

2.3 Cold resistance of the tree

2.3.1 Harmful effects of low temperature

Low temperature affects the structure and function of the roots The sharp reduction in water and minerals makes the plant lack water and nutrients

In addition, the low temperature also affects the cell membrane, the membrane of organ cells such as chlorophyocyte mitocles, thereby affecting the physiological processes of the plant In plants that do not tolerate cold lipids of the membrane have a higher proportion of saturated fatty acid chains than cold-tolerant plants, therefore, when experiencing membrane cold, it tends to change to a semi-crystal state When the fluidity of the membrane is poor, the proteins of the membrane do not work in a normal state leading to adverse consequences for the transport of substances, energy transformation and enzyme activity At the same time, the low temperature of the damaged whole membrane increases the permeability of the cell, resulting in the loss of nutrients of the cell

2.3.2 Characteristics adapted to low temperature

Plants that are resistant to low temperatures often have reduced viscosity, strong metabolism, protein synthesis processes that occur more strongly