1 Introduction
19
ability, the growth of each organ of the organism, the yield, the injured symptom
and so on as the index. The differences were recorded in different growth stages.
For traits that cannot be quantified, the damage index is calculated by population
visual classification or individual classification, and the relative damage rate or salt
(alkali) tolerance coefficient can be calculated for the measured index. It mainly
includes germination comparison method, morphological comparison method and
yield comparison method. The yield comparison method is more accurate, but this
method has long cycle, high cost and the change of year and climate has great influence, so it can only be used when there are a few materials. The morphological
comparison method is based on the visual fuzzy form standard as the classification
standard, and can only be qualitative and quantitative, and the error is large. The
indirect identification method is based on some physiological and biochemical characteristics, and indirectly determines the salt tolerance of the material to be tested.
Such as proline, betaine, albumin, boron content determination, electrolyte extravasation electro-foreign method, mass wall separation method, water potential method,
leaf green protein damage method, electro-dissolution method and the like.
Evaluation of resistance to heavy metals: excessive heavy metals in soil are a
kind of stress factor to plants, which will limit the normal growth, development and
reproduction of plants, so as to change the structure of plant communities. The resistance of plants to heavy metals means that plants can survive in a certain heavy metal
environment with high content without toxic symptoms such as decline in growth rate
or death, and can still survive and reproduce in an environment under heavy metal
pressure, and pass on this ability to the next generation of traits. Plant resistance
to heavy metals can be obtained through two ways: avoidance and tolerance. Some
plants can protect themselves from poisoning by absorbing high levels of heavy metals in the environment through some external mechanism. Called avoidance in this
case, the concentration of heavy metals in plants is not high, and tolerance means
that plants have certain physiological mechanisms so that plants can survive in a high
content of heavy metals without damage. At this time, there are high concentrations
of heavy metals in plants.
Identification of resistance to heavy metals: because of the complexity of soil
conditions, plants are also affected by other factors in addition to heavy metal factors,
so it is difficult to achieve the consistency of identification results between different
experiments and sites in field experiments. Most of them are indirect experiments,
including hematoxylin staining, nutrient solution culture and artificial heavy metal
toxic soil culture. The roots were treated with heavy metal solution without nutrient
elements for a certain time, and then the reaction of roots was observed by staining
method to judge the weight resistance of plants. Plant seedlings were cultured in
nutrient solution containing heavy metals, and then the response of root growth to
heavy metals was observed. The germinated seeds were seeded in heavy metal toxic
soil for one week, and the root length was measured to judge the resistance of different
genotypes to heavy metal.
19
ability, the growth of each organ of the organism, the yield, the injured symptom
and so on as the index. The differences were recorded in different growth stages.
For traits that cannot be quantified, the damage index is calculated by population
visual classification or individual classification, and the relative damage rate or salt
(alkali) tolerance coefficient can be calculated for the measured index. It mainly
includes germination comparison method, morphological comparison method and
yield comparison method. The yield comparison method is more accurate, but this
method has long cycle, high cost and the change of year and climate has great influence, so it can only be used when there are a few materials. The morphological
comparison method is based on the visual fuzzy form standard as the classification
standard, and can only be qualitative and quantitative, and the error is large. The
indirect identification method is based on some physiological and biochemical characteristics, and indirectly determines the salt tolerance of the material to be tested.
Such as proline, betaine, albumin, boron content determination, electrolyte extravasation electro-foreign method, mass wall separation method, water potential method,
leaf green protein damage method, electro-dissolution method and the like.
Evaluation of resistance to heavy metals: excessive heavy metals in soil are a
kind of stress factor to plants, which will limit the normal growth, development and
reproduction of plants, so as to change the structure of plant communities. The resistance of plants to heavy metals means that plants can survive in a certain heavy metal
environment with high content without toxic symptoms such as decline in growth rate
or death, and can still survive and reproduce in an environment under heavy metal
pressure, and pass on this ability to the next generation of traits. Plant resistance
to heavy metals can be obtained through two ways: avoidance and tolerance. Some
plants can protect themselves from poisoning by absorbing high levels of heavy metals in the environment through some external mechanism. Called avoidance in this
case, the concentration of heavy metals in plants is not high, and tolerance means
that plants have certain physiological mechanisms so that plants can survive in a high
content of heavy metals without damage. At this time, there are high concentrations
of heavy metals in plants.
Identification of resistance to heavy metals: because of the complexity of soil
conditions, plants are also affected by other factors in addition to heavy metal factors,
so it is difficult to achieve the consistency of identification results between different
experiments and sites in field experiments. Most of them are indirect experiments,
including hematoxylin staining, nutrient solution culture and artificial heavy metal
toxic soil culture. The roots were treated with heavy metal solution without nutrient
elements for a certain time, and then the reaction of roots was observed by staining
method to judge the weight resistance of plants. Plant seedlings were cultured in
nutrient solution containing heavy metals, and then the response of root growth to
heavy metals was observed. The germinated seeds were seeded in heavy metal toxic
soil for one week, and the root length was measured to judge the resistance of different
genotypes to heavy metal.