In order to explore the salt-tolerance of Narcissus pseudonarcissus and enrich its cultivation and application forms. In this experiment, “Manly”, “Dutch” and “Wilden” daffodils were used as test materials. NaCl stress was applied at different concentrations, and the corresponding physiological indexes were measured at three time nodes: bolting stage, early flowering stage and blooming stage. The results showed that all three showed some resistance under low concentration salt stress, in which, SOD, POD enzyme activity, chlorophyll proline and soluble sugar content increased, while MDA content decreased . The physiological metabolism of the three was disturbed under high concentration of salt stress, in which, SOD, POD enzyme activity and chlorophyll content decreased, while MDA, proline a nd soluble sugar content increased. With the extension of stress time, the injury was gradually deepened and the salt tolerance of the three varieties is “ Dutch ” , “Wilden” and “Manly” in order.
Soil salinization is a common problem in the world, and it is one of the abiotic stress factors that seriously restrict global agricultural production [
Narcissus pseudonarcissus is a perennial bulb flower of Amaryllidaceae Narcissus, which originating from Spain, Britain and other Mediterranean coastal areas [
Three imported varieties of Narcissus pseudonarcissus “Manly”, “Dutch” and “Wilden” were used as experimental materials, the substrate was mixed with peat, coconut bran, vermiculite and perlite in a ratio of 4:4:1:1, commercial seed balls with consistent specifications were selected and cultivated in a double-color basin with diameter of 10 cm and height of 8 cm, the upper covering matrix was 2 - 3 cm, which was cultured in a solar greenhouse until root and germination. Sunlight greenhouse always stay day and night temperature of 12˚C/7˚C. And shade the bulbs properly before budding.
NaCl solution with a concentration of 0 (CK), 100, 300, 500 mmol/l was used to treat the small buds when they were exposed to soil, and 30 pots of plants were used for each treatment, and 100 ml was poured from 7:00 to 9:00 in the morning, and once every two days until moss extraction. The physiological indexes of the middle of functional leaves of the same parts were measured in the three stages of bolting, early flowering and blooming.
Soluble sugar content was determined by anthrone colorimetry [
SPSS 22.0 software was used to process the test data, LSD method was used to analyze the significance of the difference, and the data was expressed as the mean value of three times.
Plant chlorophyll is involved in the absorption, transmission and transformation of light energy, and its content is an important indicator reflecting the strength of photosynthesis [
Malondialdehyde (MDA) is a product of membrane lipid peroxidation, and its content can directly reflect the degree of cell membrane damage [
Under low concentration salt stress (100 - 300 mmol/L NaCl) (
MDA content in general increase higher than their respective control, of which the most early flowering changes significantly. When the concentration is tendency for 500 mmol/L, MDA content are approximately twice the contrast, it shows that the high NaCl concentration makes the Narcissus pseudonarcissus has already happened the cell membrane lipid peroxidation, antioxidant system function of cell membrane is abate, difficult to balance the stress damage, severely damaged cell membranes, resulting in a decline in cell function and affected the physiological metabolism process of Narcissus pseudonarcissus.
MDA content of the same variety varies in different periods, and the blooming period of “Manly” is significantly higher than that of bolting stage and early flowering stage, while the “Dutch” and “Wilden” is the highest in the early flowering stage. At the same time, it can be seen that the tolerance degree of the three varieties is different. Among them, the “Dutch” is the best. In the three periods, MDA content first decreases and then increases with the increase of salt concentration, and the content is the lowest under the concentration of 100 mmol/L NaCl. The Change trend of “Manly” decreased first and then increased in the bolting stage and the early flowering stage, while it continued to increase in the blooming stage. The relative content of “Wilden” was always lower than that of “Manly” in each period, although it showed a continuous increasing trend in the three periods. This shows that the salt damage resistance of the three is “Dutch” greater than “Wilden” greater than “Manly”.
The antioxidant enzyme system in plants can eliminate peroxides such as reactive oxygen species produced during metabolism to maintain a dynamic balance in the body. Under the external salt stress, reactive oxygen species accumulate free radicals, while SOD and POD in the antioxidant enzyme system play an important role in scavenging free radicals [
The change trend of POD activity in the three varieties of Narcissus pseudonarcissus was consistent with that of SOD enzyme activity (
Narcissus pseudonarcissus showed a significant decrease in vivo, which was lower than their respective control levels, indicating that POD activity was more significantly affected by stress under the condition of high concentration of salt. The changes of POD content in different periods of the same cultivar were also different. The POD content of “Manly” and “Dutch” was the highest in the early flowering stage, while the POD content of “Wilden” was the highest in the moss extraction period, indicating that the salt tolerance of the same cultivar was different in different periods. The salt stress was more sensitive in the early stage, but gradually decreased in the later stage. At the same time, it can be seen from the figure that different varieties have different degrees of salt tolerance. “Dutch” and “Wilden” usually reach the maximum at 300 mmol/L, while “Manly” at all three periods reach the maximum at 100 mmol/L, which shows that “Dutch” and “Wilden” have strong tolerance.
Proline, as an important osmotic regulatory substance in plants, can be used as a reference index for the degree of salt and alkali stress in plants. It is essentially a highly water-soluble free amino acid in the cytoplasm, which can protect the cell membrane system, maintain the structure and function of enzymes and reduce the degradation of Intracellular protein [
On the one hand, soluble sugar can be used as osmotic regulatory substance in plants to regulate the change of osmotic potential in cells; on the other hand, it can also be used as a carbon framework for intracellular macromolecules and an energy source in plants [
decomposition quantity is greater than the amount of synthetic, results in the decrease of total soluble sugar, the plant resistance is abate, the damage is aggravating, reducing salt stress resistance ability. And “Wilden” and “Dutch” on the soluble sugar content increased with the increase of NaCl concentration in the body gradually on the rise, shows the two varieties of soluble sugar in the body under the condition of high concentration of NaCl stress decomposition quantity is limited, and decomposition of synthetic quantity is always greater than the amount, to maintain the high level state of soluble sugar in the body, thus reducing the damage of salt stress on plant. In terms of the soluble sugar content of the same variety in different periods, all three showed that the blooming period was larger than the early flowering and the bolting period, which may be caused by the increase of the soluble sugar accumulated by the extension of the growth period.
Salt stress conditions can induce a series of physiological and biochemical reactions in plants, and the comprehensive expression of these reactions affects the salt tolerance of plants [
Under the stress of high concentration of NaCl, salt-tolerant physiological and biochemical reactions in the body of 3 varieties of Narcissus pseudonarcissus were confused, and the antioxidant enzyme activities of SOD and POD were reduced. Although the content of proline and soluble sugar continued to rise, it was still difficult to resist the damage caused by high salt stress, which caused serious damage to the plasma membrane and resulted in a large accumulation of MDA content. High concentration of MDA can promote the destruction of chloroplast membrane structure and accelerate the degradation of chlorophyll. At the same time, high concentration of salt stress can also lead to the change of lamellar structure in chloroplasts, reduce the light contract ability of Narcissus pseudonarcissus and reduce the plant function [
In this experiment, with the extension of salt stress time, MDA content decreased first and then increased to an increasing trend, This suggests Narcissus pseudonarcissus with the increase of stress time hurt gradually deepened, on its own, of course, also by certain way to resist the persecution, performance of chlorophyll, soluble sugar and proline content increased, the content was higher in early flowering and flowering, both based on the extension of its own growth period accumulated materials such as chlorophyll, proline and soluble sugar increased, reflecting the plant adaptability of ego to protect a stress [
This study has some shortcomings, such as small sample size and not doing chemical analysis. The next step is to expand the determination range and combine physiological changes with chemical changes, so as to explain the influence of salt stress on Narcissus pseudonarcissus from many aspects, and to lay a sufficient theoretical foundation for the popularization and application of Narcissus pseudonarcissus on saline-alkali land.
In this experiment, 3 varieties of Narcissus pseudonarcissus all showed some resistance to salt stress environment, SOD and POD of two varieties “Dutch” and “Wilden” still show stronger activity than the control under high concentration of NaCl stress, and play a role in scavenging peroxide. At the same time, the soluble sugar content in the plants of Dutch and Wilden varieties did not significantly decrease under the condition of high salt stress, but maintained a high level, which reduced the osmotic stress brought by high salt environment. This indicated that “Dutch” and “Wilden” varieties showed better salt resistance compared with “Manly” varieties. However, all three showed physiological and metabolic dysfunction in the high-salt environment, indicating that their tolerance to salt stress injury was limited. Based on the above six physiological indicators, it is considered that the salt tolerance of the three is” Dutch “, “Wilden” and “Manly” in order.
Shandong province agricultural seed improvement project (project No. 2017LZN027).
The authors declare no conflicts of interest regarding the publication of this paper.
Wang, J.Y., Qiao, Q. and Tao, J.H. (2019) The Physiological Response of Three Narcissus pseudonarcissus under NaCl Stress. American Journal of Plant Sciences, 10, 447-461. https://doi.org/10.4236/ajps.2019.103032