18
J. Chen et al.
high yield potential, and it is difficult to provide the basis for breeders to select high
yield and drought resistance genotypes. In 1978, Fisher put forward the concept of
drought sensitivity index: drought sensitivity index = 1 − (dryland yield/water-land
yield)/(total dryland yield/tested variety water-land yield summation).
The index still fails to provide information on high and low genotypic yields. In
order to make up for the deficiency of drought resistance coefficient proposed by Chinoy [21] and drought sensitivity index proposed by Fisher (1978), Lan Jusheng et al.
(1990) put forward drought resistance index. The yield index of crop drought resistance identification has been substantially improved in biological sense. Drought
resistance index = (dryland yield × drought resistance coefficient)/mean dryland
yield of reference genotype. Hu Fushun (1997) suggested that the drought resistance
genotype must have the double standards of high yield and high drought resistance
coefficient in dryland, and set up the control at the same time. Based on this, the modified drought resistance index was proposed as an index to measure drought resistance: drought resistance index = (dryland yield/dryland yield of control varieties)
× (drought resistance coefficient/drought resistance coefficient of control varieties).
In the identification of crop drought resistance? Taking the anti-early index as the
index, good results have been obtained.
Salt resistance evaluation: the adaptability of plants to salt stress is called salt
resistance. Salt stress is one of the main environmental factors to inhibit plant growth
and reduce plant yield. According to the adaptability of plants to salt damage, it can
be divided into salt avoidance and salt tolerance. Salt avoidance refers to plants avoiding salt stress or living in high-salt habitats in various ways. In addition, halophytes
can also take various forms and physiological ways to avoid excessive salt injury.
Many halophyte protoplasts and enzymes related to metabolism can withstand high
concentration of salt stress without harm, that is, so-called salt tolerance; salt tolerance is an important mechanism of halophyte resistance to salt damage. Plant salt
tolerance is divided into biological salt tolerance and agricultural salt tolerance.
The evaluation of plant salt tolerance is mainly to study the adaptability of plants
to excessive salt content, is to study the mechanism of salt tolerance and the basis
of salt tolerance ability, and is also the key to the breeding, introduction and screening of salt tolerant plants. Plant salt resistance involves many factors of physiology
and biochemistry. It is a very complex reaction process controlled by multiple genes
and a manifestation of comprehensive traits. Because of the different salt tolerance
mode and salt tolerance mechanism of different plants, the physiological metabolism
and biochemical changes of their tissues or cells are also different, or under different salt concentration and environmental conditions, plants may resist salt toxicity
through different ways or mechanisms. Therefore, in the screening and evaluation
of salt-tolerant resources, different methods and various ways should be used to
comprehensively evaluate the salt tolerance of plants.
Identification of salt resistance: the methods of salt tolerance identification
vary according to plant and saline-alkali environment, and can be divided into two
categories: direct identification and indirect identification. The direct identification
method is to place the tested materials in the natural or artificial saline-alkali environment, taking the saline-alkali free condition as the control, taking the germination
J. Chen et al.
high yield potential, and it is difficult to provide the basis for breeders to select high
yield and drought resistance genotypes. In 1978, Fisher put forward the concept of
drought sensitivity index: drought sensitivity index = 1 − (dryland yield/water-land
yield)/(total dryland yield/tested variety water-land yield summation).
The index still fails to provide information on high and low genotypic yields. In
order to make up for the deficiency of drought resistance coefficient proposed by Chinoy [21] and drought sensitivity index proposed by Fisher (1978), Lan Jusheng et al.
(1990) put forward drought resistance index. The yield index of crop drought resistance identification has been substantially improved in biological sense. Drought
resistance index = (dryland yield × drought resistance coefficient)/mean dryland
yield of reference genotype. Hu Fushun (1997) suggested that the drought resistance
genotype must have the double standards of high yield and high drought resistance
coefficient in dryland, and set up the control at the same time. Based on this, the modified drought resistance index was proposed as an index to measure drought resistance: drought resistance index = (dryland yield/dryland yield of control varieties)
× (drought resistance coefficient/drought resistance coefficient of control varieties).
In the identification of crop drought resistance? Taking the anti-early index as the
index, good results have been obtained.
Salt resistance evaluation: the adaptability of plants to salt stress is called salt
resistance. Salt stress is one of the main environmental factors to inhibit plant growth
and reduce plant yield. According to the adaptability of plants to salt damage, it can
be divided into salt avoidance and salt tolerance. Salt avoidance refers to plants avoiding salt stress or living in high-salt habitats in various ways. In addition, halophytes
can also take various forms and physiological ways to avoid excessive salt injury.
Many halophyte protoplasts and enzymes related to metabolism can withstand high
concentration of salt stress without harm, that is, so-called salt tolerance; salt tolerance is an important mechanism of halophyte resistance to salt damage. Plant salt
tolerance is divided into biological salt tolerance and agricultural salt tolerance.
The evaluation of plant salt tolerance is mainly to study the adaptability of plants
to excessive salt content, is to study the mechanism of salt tolerance and the basis
of salt tolerance ability, and is also the key to the breeding, introduction and screening of salt tolerant plants. Plant salt resistance involves many factors of physiology
and biochemistry. It is a very complex reaction process controlled by multiple genes
and a manifestation of comprehensive traits. Because of the different salt tolerance
mode and salt tolerance mechanism of different plants, the physiological metabolism
and biochemical changes of their tissues or cells are also different, or under different salt concentration and environmental conditions, plants may resist salt toxicity
through different ways or mechanisms. Therefore, in the screening and evaluation
of salt-tolerant resources, different methods and various ways should be used to
comprehensively evaluate the salt tolerance of plants.
Identification of salt resistance: the methods of salt tolerance identification
vary according to plant and saline-alkali environment, and can be divided into two
categories: direct identification and indirect identification. The direct identification
method is to place the tested materials in the natural or artificial saline-alkali environment, taking the saline-alkali free condition as the control, taking the germination